MT2H Commercial Boiler and Volume Water Heater

Installation and Operation Instructions

Document 1211L

Installation and Operation Instructions for
MIGHTY THERM2®

Hydronic Boiler
Model MT2H
Volume Water Heater
Model MT2V
Sizes 500­2000 MBTU/h

FOR YOUR SAFETY: This product must be installed and serviced by a professional service technician, qualified in hot water boiler installation and maintenance. Improper installation and/or operation could create carbon monoxide gas in flue gases which could cause serious injury, property damage, or death. Improper installation and/or operation will void the warranty. For indoor installations, as an additional measure of safety, Laars strongly recommends installation of suitable Carbon Monoxide detectors in the vicinity of this appliance and in any adjacent occupied spaces.

WARNING
If the information in this manual is not followed exactly, a fire or explosion may result causing property damage, personal injury or loss of life.
Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other appliance.
WHAT TO DO IF YOU SMELL GAS · Do not try to light any appliance. · Do not touch any electrical switch; do not use
any phone in your building. · Immediately call your gas supplier from a
nearby phone. Follow the gas supplier’s instructions. · If you cannot reach your gas supplier, call the fire department. Installation and service must be performed by a qualified installer, service agency, or gas supplier.

AVERTISSEMENT
Assurez-vous de bien suivres les instructions données dans cette notice pour réduire au
minimum le risque d’incendie ou d’explosion ou pour éviter tout dommage matériel, toute blessure
ou la mort.
Ne pas entreposer ni utiliser d’essence ni d’autres vapeurs ou liquides inflammables dans le voisinage de cet appareil ou de tout autre appareil.
QUE FAIRE SI VOUS SENTEZ UNE ODEUR DE GAZ: · Ne pas tenter d’allumer d’appareils. · Ne touchez à aucun interrupteur. Ne pas vous servir des
téléphones dansle bâtiment où vous êtes. · Appelez immédiatement votre fournisseur de
gaz depuis un voisin. Suivez les instructions du fournisseur. · Si vous ne pouvez rejoindre le fournisseur de gaz, appelez le sservice des incendies. L’installation et l’entretien doivent être assurés par un installateur ou un service d’entretien qualifié ou par le fournisseur de gaz.

H2329100L

LAARS Heating Systems

Table of Contents

SECTION 1 General Information 1.A Introduction………………………………………………. 5 1.B Warranty ………………………………………………….. 5 1.C Model Identification……………………………………. 6 1.D Safety Notes …………………………………………….. 7 1.E Locating the unit ……………………………………….. 9 1.F Locating Pump-Mounted Water Heater
with Respect to Storage Tank(s)………………….. 9 1.G Locating Pump-Mounted Boiler
with Respect to Return/Supply Header ………… 9 1.H Locating the Unit for Correct Horizontal
Vent/Ducted Air Distance from Outside Wall …. 9 1.I Dimensions…………………………………………….. 10
SECTION 2 Venting and Combustion Air 2.A Combustion Air ……………………………………….. 12 2.A.1 Combustion Air From Room ……………………… 12 2.A.2 Intake Combustion Air ……………………………… 12 2.B Venting…………………………………………………… 12 2.B.1 Vent Categories ………………………………………. 12 2.B.2 Category I Vent……………………………………….. 13 2.B.3 Common Venting Systems ……………………….. 13 2.B.4 Category III Vent……………………………………… 14 2.C Locating Vent & Combustion Air Terminals….. 14 2.C.1 Side Wall Vent Terminal……………………………. 14 2.C.2 Side Wall Combustion Air Terminal…………….. 16 2.C.3 Vertical Vent Terminal ………………………………. 16 2.C.4 Vertical Combustion Air Terminal……………….. 16 2.D Common Vent Test — Boilers……………………. 16 2.E Vent Terminals for Outdoor Units……………….. 17

SECTION 3 Gas Supply and Piping 3.A Gas Supply and Piping …………………………….. 18

SECTION 4 Water Connections 4.A Boilers. …………………………………………………. 19 4.A.1 Heating System Piping:
Hot Supply Connections — Boiler ……………… 19 4.A.2 Cold Water Make-Up — Boiler ………………….. 19 4.A.3 Water Flow Requirements — Boiler …………… 19 4.A.4 Freeze Protection — Boiler ………………………. 20

4.B 4.B.1 4.B.2 4.B.3 4.B.4
4.B.5 4.B.6

Water Heater ………………………………………….. 20 Water System Piping — Water Heater ……….. 20 Hot Water Supply Piping — Water Heater…… 20 Water Flow Requirements — Water Heater … 20 Combined Water Heating (potable) and Space Heating — Water Heater …………. 21 Freeze Protection ­ Water Heater ……………… 21 Suggested Piping Diagrams …………………. 22-26

SECTION 5 Electrical Connections 5.A Main Power…………………………………………….. 27 5.A.1 Changing Single Circuit to Two Circuits ……… 27 6.H.1 Field Wiring…………………………………………….. 32 6.I External Staging Control Wiring ………………… 32

SECTION 6 Operating Instructions 6.A Sequence of Operation…………………………….. 32 6.B Filling the System ……………………………………. 33 6.C Operating Temperature Control …………………. 34 6.D External Boiler Operations………………………… 34 6.E Limit Controls………………………………………….. 34 6.F Operating the Burner and Set Up ………………. 34 6.F.1 Set Up for 0 to 2500 Feet Altitude ……………… 34 6.F.2 High Altitude Adjustment and Set Up………….. 35 6.G Shutting Down the Unit…………………………….. 35 6.H To Restart the Unit…………………………………… 35

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MIGHTY THERM2 Commercial Boilers and Volume Water Heaters
SECTION 7 Maintenance 7.A System Maintenance ……………………………….. 36 7.B Maintenance and Component Description ….. 36 7.B.1 Burners ………………………………………………….. 36 7.B.2 Filter………………………………………………………. 36 7.B.3 Gas Valves …………………………………………….. 36 7.B.4 Manual Reset High Limit Control……………….. 36 7.B.5 Temperature Control………………………………… 37 7.B.6 Ignition Controls………………………………………. 37 7.B.7 Ignitors/Sensor ……………………………………….. 37 7.B.8 Transformer ……………………………………………. 37 7.B.9 Blowers………………………………………………….. 37 7.B.10 Flow Switch …………………………………………… 37 7.B.11 Heat Exchanger Coil ………………………………. 37 SECTION 8 Trouble Shooting 8.A Resolving Lockouts …………………………………. 38 8.B Delayed Ignition — Possible Causes …………. 38 8.C Short Cycling — Boiler …………………………….. 39 8.D Short Cycling — Water Heater ………………….. 39 8.E High Gas Consumption ……………………………. 39 SECTION 9 Replacement Parts 9.A General Information…………………………………. 39 9.B Parts List …………………………………………… 39-47
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LAARS Heating Systems

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters

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SECTION 1 General Information

USING THIS MANUAL ­ Because these Boilers and Water Heaters are identical appliances, with the exception of materials of manufacture, labels and ultimate use and application, this manual provides information for the proper installation, operation and maintenance of both products. Where differences exist between their application and their operation, the sections pertinent to only one or the other will be so identified.
In the Commonwealth of Massachusetts, this unit must be installed by a licensed plumber or gas fitter.
1.A Introduction
This manual provides information necessary for the installation, operation, and maintenance of the Laars Heating Systems Mighty Therm2 commercial hydronic boilers and volume water heaters. Read this manual carefully before installation.
All application and installation procedures should be reviewed completely before proceeding with the installation. Consult the factory, or local factory representative, with any issues or questions regarding this equipment. Experience has shown that most operating issues are caused by improper installation.
The Mighty Therm2 is protected against over pressurization. A pressure relief valve is fitted to all units. It is installed on the outlet header, at the water outlet of the unit

NOTE: Throughout the content of this

manual, the Mighty Therm2 will be referred to

as a `unit’.

unit = MightyTherm2

1.B Warranty
Laars Heating Systems Mighty Therm2s are covered by a limited warranty. Owners should submit online warranty registration at www.Laars.com.
All warranty claims must be made to an authorized Laars Heating Systems representative, directly to Customer Service, or online at www.Laars.com.
Claims must include the serial number and model number (this information can be found on the rating plate), installation date, and name of the installer. Shipping costs are not included in the warranty
coverage.
Some accessory items are shipped in separate packages. Verify receipt of all packages listed on
the packing slip. Inspect everything for damage immediately upon delivery, and advise the carrier of any shortages or damage. Any such claims should be filed with the carrier. The carrier, not the shipper, is responsible for shortages and damage to the shipment whether visible or concealed.

GAS

INLET

VENT

GAS

PUMP
The Pump and the Hydronic Supply/Return are reversible.

HYDRONIC SUPPLY AND RETURN

Page 6
1.C Model Identification (Model Nomenclature)
Consult the rating plate on the unit. The following information describes the model number structure.
1-3 Model Series Designation M T 2 = Mighty Therm2
4 Usage H = Hydronic V = Volume Water
5-8 Size 0 5 0 0 = 500,000 BTU/h input 0 7 5 0 = 750,000 BTU/h input 1 0 0 0 = 999,000 BTU/h input 1 2 5 0 = 1,250,000 BTU/h input 1 5 0 0 = 1,500,000 BTU/h input 1 7 5 0 = 1,750,000 BTU/h input 2 0 0 0 = 1,999,000 BTU/h input
9 Fuel N = Natural Gas P = Propane
10 Altitude A = 0­10,000 feet
11 Location C = Indoor and Outdoor

LAARS Heating Systems
12 Firing Mode K = Two-stage
13 Revision 1 = First version of design
14 Heat Exchanger B = Glass-lined cast iron / copper / bronze trim (std. on water heaters) C = Glass-lined cast iron / copper (std. on boilers, n/a on water heaters) N = Glass-lined cast iron / cupro-nickel (n/a on water heaters) P = Glass-lined cast iron / cu-nickel / bronze trim
15 Option Code X = Standard unit J = CSD-1, FM, IRI, IL
16 Pump Options X = No Pump H = Pump mounted MT2V, TACO, hard water pump N = Pump mounted (any), TACO, normal water pump S = Pump mounted MT2V, TACO, soft water pump

1 2 3

4

5 67 8

9

10

11

12

13

14

MT 2

A

C

K

1

15

16

SERIES M T 2
USAGE H – HYDRONIC V – VOLUME WATER

SIZE 0 5 0 0 0 7 5 0 1 0 0 0 1 2 5 0 1 5 0 0 1 7 5 0 2 0 0 0

ALTITUDE A – 0′ ­ 10,000′

FIRING MODE
K – 2-Stage

FUEL N – NATURAL P – PROPANE

LOCATION
C – INDOOR/ OUTDOOR

REVISION
1 – FIRST REV

HEAT EXCHANGER
B – GLASS-LINED CAST IRON/ COPP/BRZ TRIM (std.MT2V)
C – GLASS-LINED CASTIRON/ COPP. (std.MT2H, n/a MT2V)
N – GLASS-LINED CAST IRON/ CU-NICKEL (n/a MT2V)
P – GLASS-LINED CAST IRON / CU-NICKEL, BRZ TRIM

HLW STAMP (MT2V only) 2 – GLASS-LINED CAST IRON/
COPPER / BRZ TRIM
5 – GLASS-LINED CAST IRON/ CU-NICKEL / BRZ TRIM

OPTIONS CODE
X – STD
J – CSD-1, GAP, FM

PUMP OPTIONS
X – NO PUMP
H – PUMP MOUNTED TACO, HARD WATER (MT2V)
N – PUMP MOUNTED, TACO, NORMAL WATER (MT2V, MT2H)
S – PUMP MTD, TACO SOFT WATER PUMP (MT2V)

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters

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1.D Safety Notes
Safety Notes are used throughout this manual to bring attention to the presence of hazards with various risk levels and to offer important information concerning the life of this product. There are 3 basic types.

1

WARNING

Indicates an imminently hazardous situation which, if not

avoided, can or will result in death or serious injury and can

or will result in catastrophic property damage.

2

CAUTION

Indicates a potentially hazardous situation which, if not avoided, may result in moderate injury and/or property damage.

3 NOTE:

Indicates instructions that are important to that topic but not related to personal injury or property damage.

WARNING
· Water temperature over 125°F (52°C) can cause severe burns instantly or death from scalds.
· Children, disabled and elderly are at highest risk of being scalded.
· See instruction manual before setting temperature at the unit.
· Feel water before bathing or showering.
· If this unit is used to produce water that could scald if too hot, such as domestic hot water use, adjust the outlet control (limit) or use temperature limiting valves to obtain a maximum water temperature of 125°F (52°C).

WARNING
This unit must be installed in accordance with the procedures detailed in this manual, or the manufacturers warranty will be voided. The installation must conform to the requirements of the local jurisdiction having authority, and, in the United States, to the latest edition
of the National Fuel Gas Code, ANSI Z223.1/NFPA54. In Canada, the installation must conform to the latest edition of CSA B149.1 Natural Gas and Propane Gas Installation Code, and/or local codes. Where required by the authority having jurisdiction, the installation of these units must conform to the Standard for Controls and Safety Devices for Automatically Fired Boilers, ANSI/ASME CSD-1. Any modifications to the boiler, its gas controls, or wiring may void the warranty. If field conditions require modifications, consult the factory representative before initiating such modifications.

WARNING
Fire or Explosion Hazard Improper configuration can cause fuel buildup and explosion. Improper user operation may result in property loss, severe physical injury, or death.
Any changes to safety-related configuration parameters must only be done by experienced and/or licensed burner/boiler operators and mechanics. If any odor of gas is detected, or if the gas burner does not appear to be functioning in a normal manner, close the main gas shutoff valve. Do not shut off the power switch. Contact your heating contractor, gas company, or factory representative.
NOTE: This unit is protected against hydronic over-pressurization. A pressure relief valve is included with each unit.

WARNING
Carbon Monoxide Hazard Improper adjustment of the burners may lead to poor combustion quality, increasing the amount of carbon monoxide produced. Excessive carbon monoxide levels may lead to personal injury or death.
WARNING
CANCER AND REPRODUCTIVE HARM. WWW.P65WARNINGS.CA.GOV.
AS REQUIRED BY THE STATE OF CALIFORNIA PROPOSITION 65.

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LAARS Heating Systems

WARNING
Electrical Shock Hazard
Electrical shock can cause severe injury, death or property damage. Disconnect the power supply before beginning installation or changing the wiring to prevent electrical shock or damage to the equipment. It may be necessary to turn off more than one power supply to disconnect.
All electrical wiring is to be done in accordance with local codes, or in the absence of local codes, with: 1) The National Electrical Code ANSI/NFPA No. 70 – latest Edition, or 2) CSA STD. C22.1 “Canadian Electrical Code – Part 1.” This appliance must be electrically grounded in accordance with these codes.

NOTE: All installations must be made in accordance with 1) American National Standard Z223.1/NFPA54-Latest Edition “National Fuel Gas Code” or 2) CSA B149.1 “Natural Gas and Propane Installation Code” or in Canada reference the B149.1 latest edition and with the requirement of the local utility or other authorities having jurisdiction. Such applicable requirements take precedence over the general instructions contained herein. All electrical wiring is to
be done in accordance with the local codes, or in the absence of local codes, with: 1) The National Electrical Code ANSI/NFPA No. 70-latest Edition, or 2) CSA STD. C22.1 “Canadian Electrical Code – Part 1”. This appliance must be electrically grounded in accordance with these codes.

WARNING
The Repair Parts list designates parts that contain refractory ceramic fibers (RCF). RCF has been classified as a possible human carcinogen. When exposed to temperatures above 180ºF, such as during direct flame contact, RCF changes into crystalline silica, a known carcinogen. When disturbed as a result of servicing or repair, these substances become airborne and, if inhaled, may be hazardous to your health.
Do not remove or replace RCF parts or attempt any service or repair work involving RCF without wearing the following protective gear:
1. A National Institute for Occupational Safety and Health (NIOSH) approved respirator.
2. Long sleeved, loose fitting clothing.
3. Gloves.
4. Eye Protection.

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters

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1.E Locating the unit
This unit should be located to provide clearances on all sides for maintenance and inspection. It should not be located in an area where leakage of any connections will result in damage to the area adjacent to the unit or to lower floors of the structure.
When such a location is not available, it is recommended that a suitable drain pan, adequately drained, be installed under the unit.
This unit is design certified by CSA-International for installation on combustible flooring; in basements; in closets, utility rooms or alcoves. These units must never be installed on carpeting. The location for the unit should be chosen with regard to the vent pipe lengths and external plumbing. The unit shall be installed such that the gas ignition system components are protected from water (dripping, spraying, rain, etc.) during operation and service (circulator replacement, control replacement, etc.). When vented vertically, this unit must be located as close as practical to a chimney or outside wall. If the vent terminal and/or combustion air terminal terminate through a wall, and there is potential for snow accumulation in the local area, both terminals should be installed at an appropriate level above grade.
The dimensions and requirements that are shown in Table 1 should be met when choosing the locations for the unit.

1.F Locating Pump-Mounted Water Heater with Respect to Storage Tank(s)
For best results, a pump-mounted water heating unit should be located within 15 feet (4.6m) of the storage tank(s). The pump is sized for 30 feet (9.1m) of piping.
If the unit must be installed with longer piping runs, then larger diameter pipe or tubing shall be used. Consult the factory for assistance.
1.G Locating Pump-Mounted Boiler with Respect to Return/Supply Header
For the best results, a pump-mounted boiler should be located within 15 feet (4.6m) of the supply and return headers. The pump is sized for 30 feet (9.1m) of piping.
If the unit must be installed with longer piping runs, then larger diameter tubing shall be used. Consult the factory for assistance.
1.H Locating the Unit for Correct Horizontal Vent/Ducted Air Distance from Outside Wall
The forced draft combustion air blower/blowers in the unit has/have sufficient power to pull air and vent properly when the following guidelines for horizontal air and vent are followed (see Table 2).

SURFACE

REQUIRED

CLEARANCE FROM

COMBUSTIBLE MATERIAL

inches

cm

RECOMMENDED

SERVICE ACCESS

CLEARANCE

inches

cm

Left Side Right Side

1

2.5

1

2.5

24

61

24

61

Top

1

2.5

12

30

Back

1

2.5

12 30**

Front

1

2.5

36

91

Vertical

(Category 1)

6*

15.2*

Vent Horizontal
(Category 3)

per UL1738 venting system supplier’s

Vent

instructions

*1″ (2.5cm) when b-vent is used. **When vent and/or combustion air connects to the back, recommended clearance is 36″ (91cm).

Table 1. Clearances

NOTE: The vent collar size is larger than the size of the vent pipe that can be used. Vent collar size and horizontal pipe diameters can be found in Table 2. The larger vent collar size is to accommodate Category I
(vertical) vent systems.
NOTE: When located on the same wall, the combustion air intake terminal must be installed a minimum of 12″ (30cm) below the exhaust vent terminal and separated by a minimum of 36 inches
(91cm) horizontally.
The air intake terminal must be installed high enough to avoid blockage from snow, leaves and other debris.

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1.I Dimensions
GAS

LAARS Heating Systems

Unit

Size

A

B

C

500

33¾ 85

16¾ 43

6½ 17

750

45¾ 116

22¾ 53

6½ 17

1000 57¾ 147

28¾ 73

6½ 17

1250 68¼ 173

34 87 10¼ 26

1500 78¾ 200

39½ 100 10¼ 26

1750 89¼ 227

44¾ 113 10¼ 26

2000 99¾ 253

49¾ 127 10¼ 26

NOTES: 1. Add 55 lbs (25kg) for pump-mounted units. Dimensions in inches cm.

Figure 1. Dimensional Data (standard units).

D 10 25 10 25 10 25 10 25 10 25 10 25 10 25

E 8 20 9½ 24 9½ 24 9 23 9 23 9 23 9 23

Air Conn.
W 6 15 8 20 8 20 12 30 12 30 12 30 12 30

Vent Conn.
V 8 20 10 25 10 25 12 30 12 30 14 36 14 36

Shipping Weight1
lbs kg 425 193 505 229 615 279 675 306 760 345 825 375 955 434

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters

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GAS

Size 500 750 1000 1250 1500 1750 2000

A 33¾ 86 45¾ 116 57¾ 147 68¼ 173 78¾ 200 89¼ 227 99¾ 253

B 16¾ 43 22¾ 58 28¾ 73 34¼ 87 39½ 100 44¾ 113 49¾ 127

C 6½ 17 6½ 17 6½ 17 10¼ 26 10¼ 26 10¼ 26 10¼ 26

D 10 25 10 25 10 25 10 25 10 25 10 25 10 25

Figure 2. Dimensional Data (pump-mounted models).

E 8 20 9½ 24 9½ 24 9 23 9 23 9 23 9 23

F 46¼ 117 58¼ 148 70¼ 178 80¾ 205 91¼ 232 101¾ 258 112¼ 285

Air Conn.
W 6 15 8 20 8 20 12 30 12 30 12 30 12 30

Vent Conn.
V 8 20 10 25 10 25 12 30 12 30 14 36 14 36

HORIZONTAL

VENT COLLAR VENT PIPE

SIZE

SIZE

DIAMETER

500 750 1000 1250 1500 1750 2000

in. cm 8 20 10 25 10 25 12 30 12 30 14 36 14 36

in. cm 6 15 8 20 8 20 10 25 10 25 12 30 12 30

INTAKE AIR PIPE
DIAMETER
in. cm 6 15 8 20 8 20 12 30 12 30 12 30 12 30

MIN. INTAKE MIN. VENT AIR PIPE LENGTH PIPE LENGTH

ft. m 0 0 0 0 0 0 0 0 0 0 0 0 0* 0

ft. m 3 1 3 1 3 1 3 1 3 1 3 1 3 1

MAX. PIPE MAX. NO. SIDE WALL

LENGTH OF ELBOWS

VENT

TERMINAL

ft. m

PART NUMBER

50 15

3

CA001401

50 15

3

CA001402

50 15

3

CA001402

50 15

3

CA001405

50 15

3

CA001405

50 15

3

CA001404

50 15

3

CA001404

SIDE WALL COMBUSTION AIR TERMINAL
PART NUMBER
CA20260701 CA20260703 CA20260703 CA20260706 CA20260706 CA20260706 CA20260706

*Appliance needs to vent outdoors using approved vent caps and following all guidelines as noted in our IO manual. Proper protection
against debris in the air intake (through using a downward spout and/or screen) to avoid debris pick-up / falling into the appliance is required.

Table 2. Horizontal Vent / Combustion Air Parameters.

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LAARS Heating Systems

SECTION 2 Venting and Combustion Air
2.A Combustion Air
These boilers and water heaters must have provisions for combustion and ventilation air in accordance with section 5.3, Air for Combustion and Ventilation, of the National Fuel Gas Code, ANSI Z223.1, or Sections 7.2, 7.3 or 7.4 of CSA B149.1, Installation Codes, or applicable provisions of the local building codes.
This unit may receive combustion air from the space in which it is installed, or it can be ducted directly to the unit from the outside. Ventilation air must be provided in either case.
2.A.1 Combustion Air From Room In the United States, the most common
requirements specify that the space shall communicate with the outdoors in accordance with method 1 or 2, which follow. Where ducts are used, they shall be of the same cross-sectional area as the free area of the openings to which they connect.
Method 1: Two permanent openings, one commencing within 12 inches (30 cm) of the top and one commencing within 12 inches (30 cm) of the bottom, of the enclosure shall be provided. The openings shall communicate directly, or by ducts, with the outdoors or spaces that freely communicate with the outdoors. When directly communicating with the outdoors, or when communicating to the outdoors through vertical ducts, each opening shall have a minimum free area of 1 square inch per 4000 BTU/hr (5.5 square cm/kW) of total input rating of all equipment in the enclosure. When communicating to the outdoors through horizontal ducts, each opening shall have a minimum free area of not less than 1 square inch per 2000 BTU/hr (11 square cm/kW) of total input rating of all equipment in the enclosure. Table 3 shows data for this sizing method, and for each model.
Method 2: One permanent opening, commencing within 12 inches (30 cm) of the top of the enclosure, shall be permitted. The opening shall directly communicate with the outdoors or shall communicate through a vertical or horizontal duct to the outdoors or spaces that
directly communicate with the outdoors and shall have a minimum free area of 1 square inch per 3000 BTU/hr (7 square cm/kW) of the total input rating of all equipment located in the enclosure. This opening must not be less than the sum of the areas of all vent connectors in the confined space.
Other methods of introducing combustion and ventilation air are acceptable, providing they conform to the requirements in the applicable codes listed above.
In Canada, consult local building and safety codes or, in absence of such requirements, follow CSA B149.1.

2.A.2 Intake Combustion Air The combustion air can be taken through the wall,
or through the roof. When taken from the wall, it must be taken from out-of- doors by means of the Manufacturers horizontal wall terminal (see Table 2). When taken from the roof, a field-supplied rain cap or an elbow arrangement must be used to prevent entry of rain water (see Figure 3).
Use single-wall galvanized pipe, per Table 4, for the combustion air intake (see Table 2 for appropriate size). Route the intake to the heater as directly as possible. Seal all joints with tape. Provide adequate hangers. The unit must not support the weight of the combustion air intake pipe. Maximum linear pipe length allowed is 50 feet (15.2m). Three elbows have been calculated into the 50-foot (15.2m) linear run. Subtract 10 allowable linear feet (3.0m) for every additional elbow used (see Table 2). When fewer than 3 elbows are used, the maximum linear pipe length allowed is still 50 feet (15.2m).
The connection for the intake air pipe is on the filter box. This unit has venting and combustion air ducting attached to the top.
In addition to air needed for combustion, air shall also be supplied for ventilation, including all air required for comfort and proper working conditions for personnel. This unit loses less than 1 percent of its input rating to the room, but other heat sources may be present.
2.B Venting
2.B.1 Vent Categories Depending upon desired venting for this unit, it may
be considered a Category I or a Category III appliance. In general, a vertical vent system will be a Category I system. However, in rare instances, a vertical vent system may be considered Category III. In the U.S., the National Fuel Gas Code (ANSI Z223.1-Latest Edition),

UNIT
SIZE
500 750 1000 1250 1500 1750 2000

EACH OPENING*

SQUARE INCHES

SQUARE CM

125

807

188

1213

250

1613

313

2020

375

2420

438

2826

500

3226

*Net Free Area in Square Inches / Square cm Area indicated is for one of two openings; one at floor level and one at the ceiling, so the total net free area could be double the figures indicated.
This chart is for use when communicating directly with the outdoors. For special conditions and alternate methods, refer to the latest edition of ANSI Z223.1.
Note: Check with louver manufacturers for net free area of louvers. Correct for screen resistance to the net free area if a screen is installed. Check all local codes applicable to combustion air.
Table 3. Combustion Air Openings.

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters

Page 13

or in Canada the CSA B149.1 (latest edition), defines a Category I vent system, and includes rules and tables to size these vent systems. If this units vertical vent system does not satisfy the criteria for Category I venting, it must be vented as a Category III system.
All vent systems which discharge horizontally (without the use of a power venter) are considered Category III vent systems.
2.B.2 Category I Vent When vented as a category I appliance, the vent
system must conform to the National Fuel Gas Code (ANSI Z223.1-Latest Edition) in the U.S., or in Canada, to CSA B149.1 (latest edition). The vent system must be sized and installed for a Category I Fan-Assisted Appliance.
If chimney height is greater than 25 feet, or if multiple units are vented into the same vertical vent, a barometric damper must be installed on each unit, such that the flue draft does not exceed (negative) 0.1″ w.c.
If using a power venter for any type of Category I venting, the draft should be set between (negative) 0.01 and 0.10″ w.c.

Proper vent sizing, construction and safety requirements from the National Fuel Gas Code, ANSI Z223.1 or in Canada, from CSA B149.1 as well as all applicable local codes must be followed.
As an additional precaution, it is recommended that a Carbon Monoxide (CO) alarm be installed in all enclosed spaces containing combustion appliances.
These units are not allowed to be vented into a common horizontal Cat III vent system (horizontal discharge or other configuration for Cat III), unless a properly sized vent fan is used, and the common vent system is properly designed by the vent fan manufacturer or a qualified engineer.
Refer to the installation and operating instructions
on all appliances to be common vented for instructions, warnings, restrictions and safety requirements. If safe operation of all appliances connected to a common vent cannot be assured, including prevention of spillage of flue gasses into living spaces, common venting should not be applied, and appliances should each be vented separately.

2.B.3 Common Venting Systems These units are Category I fan-assisted when
vented vertically and adhering to all applicable codes. When common venting a fan-assisted unit with
other other appliances through one shared vertical duct
called a “common vent”, special care must be taken by the installer to ensure safe operation. In the event that
the common vent is blocked, it is possible, especially for fan-assisted devices, to vent backwards through non-operating appliances sharing the vent, allowing combustion products to infiltrate occupied spaces. If the appliances are allowed to operate in this condition, serious injury or death may occur.

WARNING
When an existing Cat I appliance is removed or replaced, the original venting system may no longer be sized to properly vent the attached appliances. Under no circumstances should an improperly sized vent be used. An improperly sized vent may cause operational and safety problems,and could result in
serious injury, death, or property damage.

WARNING
Operation of appliances with a blocked common vent may lead to serious injury or death. If safe operation of all appliances connected to a common vent cannot be assured, including prevention of spillage of flue gasses into living spaces, common venting should not be applied, and appliances
should each be vented separately.

TERM Pipe
Joint Sealing

DESCRIPTION Single-wall galvanized steel pipe, 24 gauge minimum (either insulated or non-insulated)
Permanent duct tape or aluminum tape

Table 4. Required Combustion Air Piping Material.

Figure 3. Combustion Air and Vent Through Roof.

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LAARS Heating Systems

2.B.4 Category III Vent When this unit is vented with horizontal discharge,
it must be installed per this installation manual and the venting system manufacturer’s installation instructions. The vent system must be sealed stainless steel (see Table 5).
Route the vent pipe to the heater as directly
as possible. Seal all joints and provide adequate hangers every 4′ or as required in the venting system manufacturer’s Installation Instructions. Horizontal portions of the venting system must be supported to prevent sagging and may not have any low sections that could trap condensate. The unit must not support the weight of the vent pipe. Horizontal runs must slope downwards not less than ¼ inch per foot (2 cm/m) from the unit to the vent terminal. Reference Table 2 for the size of the Category III vent system. Up to three elbows can be used with 50 linear feet (15.2m) of pipe. Subtract 10 allowable linear feet (3.0m) for every additional elbow used.

4. Locate the vent terminal so that vent gases cannot enter the building through doors, windows, gravity inlets or other openings. When possible, locations under windows or near doors should be avoided.
5. Locate the vent terminal so that it cannot be blocked by snow. The National Fuel gas code requires that it be at a minimum of 12″ above grade. In a location that has the possibility of snow accumulation, it is critical the installer places the vent at least 12″ higher than the maximum potential snow line. Seek local municipalities and their codes for appropriate installation techniques.
6. Locate the terminal so the vent exhaust does not settle on building surfaces or other nearby objects. Vent products may damage such surfaces or objects.
7. If the boiler or water heater uses ducted combustion air from an intake terminal located on the same wall, locate the vent terminal at least 3 feet (0.9m) horizontally from the combustion air terminal, and locate the vent terminal at least 1 foot
(0.3m) above the combustion air terminal.

WARNING
The outdoor vent terminal gets hot. This unit must be installed in such a way as to reduce the risk of
burns from contact with the vent terminal.
2.C Locating Vent & Combustion Air Terminals
2.C.1 Side Wall Vent Terminal The appropriate manufacturers side wall vent
hood must be used, and is listed in the installation and operation manual. The terminal provides a means of installing the vent piping through the building wall, and must be located in accordance with ANSI Z223.1/ NFPA 54 and applicable local codes. In Canada, the installation must be in accordance with CSA B149.1 or .2 and local applicable codes. Consider the following when installing the terminal: 1. Figure 4 shows the requirements for mechanical vent
terminal clearances for the U.S. and Canada. 2. Vent terminals for condensing appliances or
appliances with condensing vents are not permitted to terminate above a public walkway, or over an area where condensate or vapor could create a nuisance or hazard. 3. Locate the vent terminal so that vent gases cannot be drawn into air conditioning system inlets.

TERM
Pipe
Joint Sealing

DESCRIPTION
Must comply with UL Standard 1738 such as Type 29-4C Stainless Steel (either insulated or non-insulated). Follow vent manufacturer’s instructions

Table 5. Required Horizontal Venting Material.

2.C.2 Side Wall Combustion Air Terminal The manufacturers side wall combustion air
terminal (see Table 2) must be used when the unit takes its combustion air through a duct from a side wall. Consider the following when installing the terminal: 1. Do not locate the air inlet terminal near a source
of corrosive chemical fumes (e.g., cleaning fluid, chlorinated compounds, etc.) 2. Locate the terminal so that it will not be subject to damage by accident or vandalism. 3. Locate the combustion air terminal so that it cannot be blocked by snow. The National Fuel gas code requires that it be at a minimum of 12″ above grade. Depending on local conditions, the installer should ensure that it remains at least 12″ above the maximum potential snow line. Seek local municipalities and their codes for appropriate installation techniques.
WARNING
It is critical that the combustion air intake and the vent terminals remain at least 12″ above the maximum potential snow line. If either the vent terminal or the
air terminal is blocked by snow, there may be potential for the unit to produce excess carbon monoxide and or recirculate flue gasses into the building/dwelling. Personal injury or DEATH may occur. Natural snowfall, drifting, and banking should all be taken into account
when locating the terminals in a potential snow environment.
4. If this unit is side-wall vented to the same wall, locate the vent terminal at least 3 feet (0.9m) horizontally from the combustion air terminal, and locate the vent terminal at least 1 foot (0.3m) above the combustion air terminal (see Figure 4).

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters

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Canadian Installations1

A = Clearance above grade, veranda, porch, deck, or balcony

12 in (30 cm)

B = Clearance to window or door that may be opened

6 in (15 cm) for appliances 10,000 Btuh (3 kW) 12 in (30 cm) for appliances > 10,000 Btuh (3 kW) and
100,000 Btuh (30 kW) 36 in (91 cm) for appliances >100,000 Btuh (30 kW)

C = Clearance to permanently closed window

See Note 4

D = Vertical clearance to ventilated soffit located above the terminal within a horizontal distance of 2 ft (61 cm) from the center line of the terminal
E = Clearance to unventilated soffit

See Note 4 See Note 4

F = Clearance to outside corner

See Note 4

G = Clearance to inside corner

See Note 4

H = Clearance to each side of centerline extended above meter / regulator assy

3 ft (91 cm) within a height of 15 ft (4.6 m)

I = Clearance to service regulator vent outlet 3 ft (91 cm)

J = Clearance to nonmechanical air supply inlet to building or the combustion air inlet to any other appliance

6 in (15 cm) for appliances 10,000 Btuh (3 kW) 12 in (30cm) for appliances > 10,000 Btuh (3 kW) and
100,000 Btuh (30 kW) 36 in (91 cm) for appliances > 100,000 Btuh (30 kW)

K = Clearance to a mechanical air supply inlet
L = Clearance above paved sidewalk or paved driveway located on public property

6 ft (1.83 m) 7 ft (2.13 m)

M = Clearance under veranda, porch, deck, or 12 in (30 cm) balcony

U.S. Installations2
12 in (30 cm)
6 in (15 cm) for appliances 10,000 Btuh (3 kW) 9 in (23 cm) for appliances > 10,000 Btuh (3 kW) and
50,000 Btuh (15 kW) 12 in (30 cm) for appliances >50,000 Btuh (15 kW)
See Note 5 See Note 5
See Note 5 See Note 5 See Note 5 See Note 5
See Note 5 6 in (15 cm) for appliances 10,000 Btuh (3 kW) 9 in (23cm) for appliances > 10,000 Btuh (3 kW) and
50,000 Btuh (15 kW) 12 in (30 cm) for appliances > 50,000 Btuh (15 kW) 3 ft (91 cm) above if within 10 ft (3 m) horizontally 7 ft (2.13 m) for mechanical draft systems (Category I appliances). Vents for Category II and IV appliances cannot be located above public walkways or other areas where condensate or vapor can cause a nuisance or hazard*
See Note 5

A vent shall not terminate directly above a sidewalk or paved driveway that is located between two single family dwellings and serves both dwellings. Permitted only if veranda, porch, deck, or balcony is fully open on a minimum of two sides beneath the floor.

Notes:

1. In accordance with the current CSA B149.1, Natural Gas and Propane Installation Code. 2) In accordance with the current ANSI Z223.1/NFPA 54, Natural Fuel Gas Code. 3) If locally adopted installation codes specify clearances different than those illustrated, then the most stringent clearance shall prevail. 4) For clearances not specified in CAN/CSA-B149, clearance is in accordance with local installation codes and the requirements of the gas supplier. 5) For clearances not specified in ANSI Z223.1/ NFPA 54, clearance is in accordance with local installation codes and the requirements of the gas supplier. 6) IMPORTANT: Terminal must be placed such that it remains a minimum of 12″ above maximum expected snow line. Local codes may have more specific
   requirements, and must be consulted.

*When vent terminal is less than 10 feet (3m) horizontally from a forced air inlet, the terminal must be at least 3 feet (0.9m) above the air inlet. (US only)

Figure 4. Combustion Air and Vent Through Side Wall.

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LAARS Heating Systems

2.C.3 Vertical Vent Terminal When the unit is vented through the roof, the vent
must extend at least 3 feet (0.9m) above the point at
which it penetrates the roof. It must extend at least 2
feet (0.6m) higher than any portion of a building within a
horizontal distance of 10 feet (3.0m), and high enough
above the roof line to prevent blockage from snow. When
the combustion air is taken from the roof, the combustion
air must terminate at least 12″ (30cm) below the vent
terminal (see Figure 3). Seek local municipalities and
their codes for appropriate installation techniques.
From Massachusetts Rules and Regulations 248 CMR 5.08: (a) For all side wall horizontally vented gas fueled equip-
ment installed in every dwelling, building or structure used in whole or inpart for residential purposes, including those owned or operated by the Commonwealth and where the side wall exhaust vent termination is less than
seven (7) feet above finished grade in the area of the venting, including but not limited to decks and porches, the following requirements shall be satisfied: 1. INSTALLATION OF CARBON MONOXIDE DETECTORS. At the time of installation of the side wall horizontal vented gas fueled equipment, the installing plumber or gasfitter shall observe that a hard-wired carbon monoxide detector with an alarm and battery back-up is installed on the floor level where the gas equipment is to be installed. In addition, the installing plumber or gasfitter shall observe that a battery operated or hard-wired carbon monoxide detector with an alarm is installed on each additional level of the dwelling, building or structure served by the side wall horizontal vented gas fueled equipment. It shall be the responsibility of the property owner to secure the services of qualified licensed professionals for the installation of hard-wired carbon monoxide detectors.
a. In the event that the side wall horizontally vented gas
fueled equipment is installed in a crawl space or an attic, the hard-wired carbon monoxide detector with alarm and battery back-up may be installed on the next adjacent floor level. b. In the event that the requirements of this subdivision cannot be met at the time of completion of installation, the owner shall have a period of thirty (30) days to comply with the above requirements; provided, however, that during said thirty (30) day period, a battery operated carbon monoxide detector with an alarm shall be installed. 2. APPROVED CARBON MONOXIDE DETECTORS. Each carbon monoxide detector as required in accordance with the above provisions shall comply with NFPA 720 and be ANSI/ UL 2034 listed and IAS certified. 3. SIGNAGE. A metal or plastic identification plate shall be permanently mounted to the exterior of the building at a minimum height of eight (8) feet above grade directly in line with the exhaust vent terminal for the horizontally vented gas fueled heating appliance or equipment. The sign shall read, in print size no less than one-half (½) inch in size, “GAS VENT DIRECTLY BELOW. KEEP CLEAR OF ALL OBSTRUCTIONS”. 4. INSPECTION. The state or local gas inspector of the side wall horizontally vented gas fueled equipment shall not approve the installation unless, upon inspection, the inspector
observes carbon monoxide detectors and signage installed in accordance with the provisions of 248 CMR 5.08(2)(a) 1 through 4. (b) EXEMPTIONS: The following equipment is exempt from 248 CMR 5.08(2)(a) 1 through 4: 1. The equipment listed in Chapter 10 entitled “Equipment Not Required To Be Vented” in the most current edition of NFPA 54 as adopted by the Board; and 2. Product Approved side wall horizontal vented gas fueled

equipment installed in a room or structure separate from the dwelling, building or structure used in whole or in part for residential purposes. (c) MANUFACTURER REQUIREMENTS – GAS EQUIPMENT VENTING SYSTEM PROVIDED. When the manufacturer of Product Approved side wall horizontally vented gas equipment provides a venting system design or venting system components with the equipment, the instructions provided by the manufacturer for installation of the equipment and the venting system shall include: 1. Detailed instructions for the installation of the venting system design or the venting system components; and 2. A complete parts list for the venting system design or venting system. (d) MANUFACTURER REQUIREMENTS – GAS EQUIPMENT VENTING SYSTEMNOT PROVIDED. When the manufacturer of a Product Approved side wall horizontally vented gas fueled equipment does not provide the parts for venting the fuel gases, but identifies “special venting systems”, the following requirements shall be satisfied by the manufacturer: 1. The identification of each “special venting system” shall include either the listing of the website, phone number or manufacturer’s address where the venting system installation instructions can be obtained; and 2. The “special venting systems” shall be Product Approved by the Board, and the instructions provided with that system shall include a parts list and detailed installation instructions. (e) A copy of all installation instructions for the Product Approved side wall horizontally vented gas fueled equipment, and all the venting instructions, parts lists, and/or design instructions for the venting system shall remain with the appliance or equipment at the completion of the installation. Manufacturers’ websites where venting system installation instructions may be obtained is located on the manufacturers website (see back cover).
2.C.4 Vertical Combustion Air Terminal When combustion air is taken from the roof, a
field-supplied rain cap or an elbow arrangement must be used to prevent entry of rain water (see Figure 3). The opening on the end of the terminal must be at least 12″ (30cm) above the point at which it penetrates the roof, and high enough above the roof line to prevent blockage from snow. When the vent terminates on the roof, the combustion air must terminate at least 12″ (30cm) below the vent terminal.
2.D Common Vent Test — Boilers
When an existing boiler is removed from a common venting system, the common venting system is likely to be too large for proper venting of the appliances remaining connected to it.
At the time of removal of an existing boiler, the following steps shall be followed with each appliance remaining connected to the common venting system placed in operation, while the other appliances remaining connected to the common venting system are not in operation.
1. Seal any unused openings in the common venting system.
2. Visually inspect the venting system for proper size and horizontal pitch and determine there is

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters

Page 17

no blockage or restriction, leakage, corrosion and other deficiencies which could cause an unsafe condition.
3. Insofar as it is practical, close all building doors and windows and all doors between the space in which the appliances remaining connected to the common venting system are located and other spaces of the building. Turn on clothes dryers and any appliance not connected to the common venting system. Turn on any exhaust fans, such as range hoods and bathroom exhausts, so they will operate at maximum speed. Do not operate a summer exhaust fan. Close fireplace dampers.
4. Place in operation the appliance being inspected. Follow the lighting instructions. Adjust thermostat so that the heating unit will operate continuously.
5. Test for spillage at the draft hood relief opening
after 5 minutes of main burner operation. Use the flame of a match or candle, or smoke from a cigarette, cigar or pipe.
6. After it has been determined that each appliance remaining connected to the common venting system properly vents when tested as outlined above, return doors, windows, exhaust fans, fireplace dampers and any other gas burning appliance to their previous conditions of use.
7. Any improper operation of the common venting system should be corrected so that the installation conforms to the National Fuel Gas Code, ANSI Z223.1/NFPA 54 and/or CSA B149.1, Installation Codes. When resizing any portion of the common venting system, the common venting system should be resized to approach the minimum size as determined using the appropriate tables in Part II of the National Fuel Gas Code, ANSI Z223.1/NFPA 54 and/or CSA B149.1, Installation Codes.

• 2.E Vent Terminals for Outdoor Units For outdoor applications, the vent and combustion air openings must be covered with proper terminals to prevent rain, snow and other objects from falling into the unit.
  If local codes allow, outdoor installations may use 1′ of appropriately sized galvanized single wall or B-Vent and a rain cap for exhaust vent termination in the default configuration (venting out of the top). Note that some local codes may require a higher vertical vent height, extending above any perimeter fencing, etc. In installations where the appearance of the vent is
  objectionable, the low profile vent terminals in Table 6 may be used.
  Combustion air inlets consist of appropriately sized galvanized pipe and elbows to allow the open end to face down aside the boiler. This is available as a Commercial Kit from the manufacturer.
  Part numbers for the low profile terminals to cover the vent and combustion air openings are shown in Table 6.

SIZE
500 750 1000 1250 1500 1750 2000

OUTDOOR VENT TERMINAL
20254703 20254705 20254705 D2007700 D2007700 D2007800 D2007800

OUTDOOR
COMBUSTION AIR TERMINAL
CA014701 CA014702 CA014702 CA014704 CA014704 CA014704 CA014704

Table 6. Vent Terminals for Outdoor Units.

*Outdoor installation of volume water heaters is not permitted in Canada.

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LAARS Heating Systems

SECTION 3 Gas Supply and Piping

3.A Gas Supply and Piping
Gas piping should be supported by suitable hangers or floor stands, not by the boiler or water heater.
This units gas train allows the user to pipe the gas
from either the right side or the left side of the unit. As shipped, the right side of the gas train is capped off, and there is a manual valve on the left side. If desired, the manual valve on the left side of the gas train may be moved to the right side, and the cap on the right side may be moved to the left.
Review the following instructions before proceeding with the installation.

1. Verify that the unit is fitted for the proper type of gas by checking the rating plate. These units are equipped to operate at elevations up to 10,000 feet (3050m) and may be adjusted to operate properly at altitudes above 2500 feet (see Section 6.F.2) and the input will be reduced if the heating value of the gas supply is below sea level values.
2. Verify the inlet gas supply pressure.

Min

Max

Natural Gas 3.5″ W.C.

10.5″ W.C.

Propane

8″ W.C.

13″ W.C.

3. Refer to Table 7, size supply. 4. Run gas supply line in accordance with all applicable
codes.
5. Locate and install manual shutoff valves in accordance with state and local requirements.
6. A sediment trap must be provided upstream of the gas controls.
7. All threaded joints should be coated with piping compound resistant to action of liquefied petroleum gas.
8. The unit and its individual shutoff valve must be disconnected from the gas supply piping during any pressure testing of that system at test pressures in excess of 1/2 PSIG (3.45kpa).
9. The unit must be isolated from the gas supply system by closing its individual manual shutoff valve during any pressure testing of the gas supply
piping system at test pressures equal to or less than 1/2 PSIG (3.45kpa). 10. The unit and its gas connection must be leak tested before placing it in operation. 11. Purge all air from gas lines.

NOTE: This unit and all other gas appliances sharing
the gas supply line must be firing at maximum capacity to properly measure the inlet supply pressure. The pressure can be measured at the supply pressure port on the gas valve. Low gas pressure could be an
indication of an undersized gas meter, undersized gas supply lines and/or an obstructed gas supply line.

WARNING
If an inline high gas pressure regulator is used, it must be of the lockup type and located a minimum of 10 feet from the unit. Failure to do so may result in
insufficient gas volume supplied to the unit.

WARNING
Do not use open flame to check for leaks. An open flame could lead to explosion, which could result
in property damage, serious injury or death.

SIZE AND GAS TYPE
500 natural 500 propane 750 natural 750 propane 1000 natural 1000 propane 1250 natural 1250 propane 1500 natural 1500 propane 1750 natural 1750 propane 2000 natural 2000 propane

DISTANCE FROM GAS METER OR LAST STAGE REGULATOR

0-100′

100-200′

200-300′

1½”

2″

2″

1″

1½”

1½”

2″

2″

2½”

1½”

1½”

2″

2″

2½”

3″

1½”

2″

2½”

2½”

2½”

3″

2″

2″

2½”

2½”

3″

3″

2″

2½”

2½”

2½”

3″

3″

2″

2½”

2½”

3″

3″

3½”

2½”

2½”

3″

Metric Equivalent
SIZE AND GAS TYPE
500 natural 500 propane 750 natural 750 propane 1000 natural 1000 propane 1250 natural 1250 propane 1500 natural 1500 propane 1750 natural 1750 propane 2000 natural 2000 propane

DISTANCE FROM GAS METER OR LAST STAGE REGULATOR

0-31m

31-61m

61-91m

3.8cm 2.5cm

5.1cm 3.8cm

5.1cm 3.8cm

5.1cm 3.8cm

5.1cm 3.8cm

6.4cm 5.1cm

5.1cm 3.8cm 6.4cm 5.1cm

6.4cm 5.1cm 6.4cm 5.1cm

7.6cm 6.4cm 7.6cm 6.4cm

6.4cm 5.1cm 6.4cm 5.1cm

7.6cm 6.4cm 7.6cm 6.4cm

7.6cm 6.4cm 7.6cm 6.4cm

7.6cm 6.4cm

7.6cm 6.4cm

8.9cm 7.6cm

NOTES: 1. These figures are based on 1/2″ (0.12kPa) water column pressure drop. 2. Check supply pressure and local code requirements before proceeding with work. 3. Pipe fittings must be considered when determining gas
pipe sizing.

Table 7. Gas Piping Sizes.

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters

Page 19

SECTION 4 Water Connections
4.A Boilers.
4.A.1 Heating System Piping: Hot Supply Connections — Boiler
NOTE: This unit must be installed in a closed pressure system with a minimum of 12 psi (82.7kPa) static pressure at the boiler. Hot water piping should be supported by suitable
hangers or floor stands. Do not support piping with this unit. Due to expansion and contraction of copper pipe, consideration should be given to the type of hangers used. Rigid hangers may transmit noise through the system resulting from the piping sliding in the hangers. It is recommended that padding be used when rigid hangers are installed. Maintain 1″ clearance to combustibles for hot water pipes.
Pipe the discharge of the relief valve (full size) to a drain or in a manner to prevent injury in the event of pressure relief. Install an air purger, an air vent, a diaphragm-type expansion tank, and a hydronic flow check in the system supply loop. Minimum fill pressure must be 12psig (82.7kPa). Install shutoff valves where required by code.
Suggested piping diagrams are shown (see Figures 6 through 10 on page 22). These diagrams are meant only as a guide. Components required by local codes must be properly installed.
4.A.2 Cold Water Make-Up — Boiler 1. Connect the cold water supply to the inlet
connection of an automatic fill valve. 2. Install a suitable back flow preventer between the
Figure 5. Typical Gas Train Configuration.

automatic fill valve and the cold water supply. 3. Install shut off valves where required.
NOTE: This boiler, when used in connection with a refrigeration system, must be installed so the chilled
medium is piped in parallel with the boiler with appropriate valves to prevent the chilled medium from
entering the boiler.
The boiler piping system of a hot water heating boiler connected to heating coils located in air handling appliances where they may be exposed to refrigerated air circulation must be equipped with flow control valves or other automatic means to prevent gravity circulation of the boiler water during the cooling cycle.
A boiler installed above radiation level, or as required by the authority having jurisdiction, must be provided with a low water cutoff device either as a part of the boiler or at the time of boiler installation.
4.A.3 Water Flow Requirements — Boiler A hydronic heating (closed loop) application
re-circulates the same fluid in the piping system. As a result, no new minerals or oxygen is introduced into the system. To ensure a proper operating temperature leading to long boiler life, a flow rate has been established based on the fluid temperature rise for this specific size boiler.
Pump-mounted boilers can be ordered for use in primary secondary piping systems. The pumps used are sized for the headloss through the heater, plus 30 feet (9.1m) of full-sized piping (same size as boiler outlet) and a normal number of fittings.

Unit

20°F

Size

flow H/L

500 750 1000 1250 1500 1750

gpm feet
43 1.7 64 3.3 85 5.0 106 8.1 128 10.0 N/R N/R

2000 N/R N/R

Metric Equivalent

Unit

11°C

Size

flow H/L

lpm

m

500 161 0.5

750 241 1.0

1000 321 1.5

1250 401 2.5

1500 483 3.0

1750 N/R N/R

2000 N/R N/R

25°F
flow H/L
gpm feet
34 1.1 51 2.3 68 3.6 85 6.1 102 7.2 119 10.5 136 12.5

30°F
flow H/L
gpm feet
28 0.9 43 1.7 57 3.1 71 4.7 85 5.5 99 8.4 113 10.4

35°F
flow H/L
gpm feet
24 0.7 36 1.2 49 2.2 61 3.4 73 4.2 85 5.8 97 8.3

14°C
flow H/L
lpm m
129 0.3 193 0.7 257 1.1 322 1.9 386 2.2 451 3.2 515 3.8

17°C
flow H/L
lpm m
107 0.3 161 0.5 214 0.9 269 1.4 322 1.7 375 2.6 429 3.2

19°C
flow H/L
lpm m
92 0.2 138 0.4 184 0.7 231 1.0 276 1.3 322 1.8 368 2.5

Notes: gpm = gallons per minute, lpm = liters per minute, H/L = headloss, ft = headloss in feet, m = headloss in meters. Maximum temperature rise is 35°F (19°C), as shown. Headloss is for boiler’s heat exchanger only. N/R = not recommended.

Table 8. Water Flow Requirements — Boilers.

Page 20

LAARS Heating Systems

Table 8 specifies water flow rates for boilers, which will enable the user to size a pump. The headloss shown is for the heater only, and the user will need to add the headloss of the system piping to properly size the pump.
The minimum inlet water temperature for the this unit is 120°F (49°C) to avoid condensing on the copper coils.
4.A.4 Freeze Protection — Boiler Boiler installations are not recommended in areas
where the danger of freezing exists unless proper precautions are made for freeze protection. A non toxic, heating system, anti-freeze may be added to the hydronic system provided that the concentration does not exceed 50% and the anti freeze contains an anti foamant. When a 50/50 mixture is used, increase the water flow requirements by 15%, and increase the headloss requirements by 20%.
Power outage, interruption of gas supply, failure of system components, activation of safety devices, etc., may prevent a boiler from firing. Any time a boiler is subjected to freezing conditions, and the boiler is not able to fire, and/or the water is not able to circulate, there is a risk of freezing in the boiler or in the pipes in the system. When water freezes, it expands. This can result in bursting of pipes in the system, or damage to the boiler, which could result in leaking or flooding conditions.
NOTE: Different glycol products may provide varying degrees of protection. Glycol products must be
maintained properly in a heating system, or they may become ineffective. Consult the glycol specifications,
or the glycol manufacturer, for information about specific products, maintenance of solutions, and set up
according to your particular conditions.

30 feet (9.1m) of full-sized piping (same size as boiler outlet) and a normal number of fittings. Pumps used on pump-mounted unit are sized for soft/normal or hard water, so make sure a pump-mounted unit matches the water quality of the installation.
Pipe the outlet from the heater’s relief valve such that any discharge from the relief valve will be conducted to a suitable place for disposal when relief occurs. Do not reduce line size or install any valves in this line. The line must be installed to allow complete drainage of both the valve and the line.
Suggested piping diagrams are shown in Figures 11 through 14 on page 24. These diagrams are meant only as a guide. Components required by local codes must be properly installed.
The minimum inlet water temperature for this unit is 120°F (49°C) to avoid condensing on the copper coils.
4.B.2 Hot Water Supply Piping — Water Heater Follow the tank manufacturer’s guidelines for
completion of the hot water system connections.
NOTE: A temperature and pressure relief valve, listed as complying with the Standard for Relief Valves and Automatic Gas Shutoff Devices for Hot Water
Supply Systems (ANSI Z21.22 / CSA 4.4) of suitable discharge capacity, must be installed in the separate
storage tank system.
If this water heater is installed in a closed water supply system, such as one having a backflow preventer in the cold water supply line, the relief valve may discharge periodically, due to thermal expansion. A properly-sized expansion tank (or other means) must be provided to control thermal expansion. Contact the water supplier or local plumbing inspector on how to control this situation.

4.B Water Connections — Water Heaters
4.B.1 Water System Piping — Water Heater Hot water piping should be supported by suitable
hangers or floor stands. Do not support piping with this unit. Due to expansion and contraction of copper pipe, consideration should be given to the type of hangers used. Rigid hangers may transmit noise through the system resulting from the piping sliding in the hangers. It is recommended that padding be used when rigid hangers are installed.
This unit can be used with several different types of readily available storage tanks. A pump draws water from the storage tank and pumps the water through the heater and back into the tank. Pump-mounted units have a circulating pump built into the water heater. The pumps used are sized for the headloss through the heater, plus

4.B.3 Water Flow Requirements — Water Heater In a water heating application (an open system),
new water is constantly being introduced. With the new water comes a fresh supply of minerals that can be deposited on the units heat exchanger. This is commonly known as scaling. The amount of minerals will depend upon the hardness of the water. Water can
also be aggressive, and can erode metals, including copper, if the water is moved too quickly. The water flow requirements for this units water heater are based upon the hardness of the water. The water flow is kept high enough to prevent scaling, but low enough to prevent tube erosion. For extremely soft or hard water, cupronickel tubes are available. Contact a manufacturers representative if you have questions or concerns about water quality.
Pump-mounted water heaters can be ordered with standard pumps for soft or normal water or with pumps for hard water. The pumps used are sized for the headloss through the heater, plus 30 feet (9.1m) of full-

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters
sized piping (same size as heater outlet) and a normal number of fittings.
Table 9 specifies water flow rates for water heaters, which will enable the user to size a pump. The headloss shown is for the heater only, and the user will need to add the headloss of the piping system to properly size the pump.
4.B.4 Combined Water Heating (potable) and Space Heating — Water Heater
NOTE: These systems are not allowed in the Commonwealth of Massachusetts.
Piping and components connected to this water heater for the space heating application shall be suitable for use with potable water.
Toxic chemicals, such as used for boiler treatment, shall not be introduced into the potable water used for space heating.
This water heater when used to supply potable water shall not be connected to any heating system or component(s) previously used with a non-potable water heating appliance.
When the system requires water for heating at temperatures higher than required for other uses, an anti-scald mixing or tempering valve shall be installed to temper the water for those uses in order to reduce scald hazard potential.
4.B.5 Freeze Protection ­ Water Heater Although these water heaters are design-certified

• for outdoor installations such installations are not
  recommended in areas subject to freezing temperatures, unless proper precautions are taken.
  Power outage, interruption of gas supply, failure of system components, activation of safety devices, etc., may prevent a heater from firing. Any time a heater is subjected to freezing conditions, and the heater is not able to fire, and/or the water is not able to circulate, there is a risk of freezing in the heater or in the pipes in the system. When water freezes, it expands. This can result in bursting of pipes in the system, or damage to the heater, which could result in leaking or flooding conditions.
  Contact your manufacturer’s representative for additional information.
  *Outdoor installation of volume water heaters is not permitted in Canada.

Page 21

Page 22 4.B.6 Suggested Piping Diagrams

LAARS Heating Systems

Figure 6. Hydronic Piping — Multiple Boilers, Primary Secondary System.

Figure 7. Hydronic Piping — Multiple Boilers, Low Temperature System.

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters

Page 23

Figure 8. Hydronic Piping — One Boiler, Multi-Temperature System. Figure 9. Hydronic Piping – Primary-Secondary, Reverse-Return.

Page 24

LAARS Heating Systems

Figure 10. Hydronic Piping – Primary-Secondary, Reverse-Return, Low Temperature. Figure 11. Water Heater Piping — One Heater, One Tank.

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters

Page 25

Figure 12. Water Heater Piping — Multiple Heaters, One Tank. Figure 13. Water Heater Piping — One Heater, Multiple Tanks.

Page 26

LAARS Heating Systems

Figure 14. Water Heater Piping — Multiple Heaters, Multiple Tanks.

Unit Size 500 750 1000 1250 1500 1750 2000

gpm S N H 45 68 90 45 68 90 45 68 90 68 68 90 68 68 90 68 68 90 112 112 112

ft SN H 1.8 2.3 3.5 2.1 3.0 6.0 2.3 3.6 6.1 3.8 3.8 6.3 3.9 3.9 6.5 4.0 4.0 6.7 10.0 10.0 10.0

Temp Rise °F S NH 19 13 9 28 19 14 38 25 19 31 31 24 38 38 28 44 44 33 30 30 30

lpm SN H 170 257 341 170 257 341 170 257 341 257 257 341 257 257 341 257 257 341 424 424 424

m S N H 0.5 0.7 1.1 0.6 0.9 1.8 0.6 1.1 1.9 1.2 1.2 1.9 1.2 1.2 2.0 1.2 1.2 2.0 3.0 3.0 3.0

NOTES:

S = soft water (1 to 7.5 grains hardness). N = normal water (7.6 to 17 grains hardness). H = hard water (more than 17 grains hardness). gpm = gallons per minute; lpm = liters per minute; ft = headloss in feet; m = headloss in meters. Headloss is for heater’s heat exchanger only.

Table 9. Water Flow Requirements — Water heaters.

Temp Rise °C SN H 10 7 5 16 10 8 21 14 10 17 17 13 21 21 16 24 24 18 17 17 17

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters

Page 27

SECTION 5 Electrical Connections
WARNING
This unit must be electrically grounded in accordance with the requirements of the authority having jurisdiction or, in the absence of such requirements, with the latest edition of the National Electrical Code, ANSI/NFPA 70, in the U.S.
and with latest edition of CSA C22.1 Canadian Electrical Code, Part 1, in Canada. Do not rely on the gas or water piping to ground the metal parts of the boiler. Plastic pipe
or dielectric unions may isolate the boiler electrically. Service and maintenance personnel, who work on or around the boiler, may be standing on wet floors and could
be electrocuted by an ungrounded boiler.
Single pole switches, including those of safety controls and protective devices must not be wired in a grounded line.
All electrical connections are made in the field wiring terminal strip, which is located at the right side of the unit.
NOTE: All internal electrical components have been prewired. No attempt should be made to connect electrical
wires to any other location except the wiring box
5.A Main Power
Non-pump-mounted heaters require a single 120-volt fused supply. See Figure 15 for over current protection ratings.
Pump-mounted models 500 to 1500 use a single 120-volt fused supply. The installer can change these units to use a separate circuit for the pump, if desired. Instructions to make this change are found in

Section 5.1.1. Pump-mounted models 1750 and 2000 require
two 120-volt fused supplies. See Figure 15 for over current protection ratings.
5.A.1 Changing Single Circuit to Two Circuits Sizes 500 to 1500 will be shipped from the factory
for a single 120-volt power supply. To use a separate circuit for the pump:
1. Ensure power is disabled to the unit. 2. Remove the three jumper wires that connect the L2, N2 and GROUND wires on terminal block 1 to the main distribution terminal block. These wires will be black/white, white and green respectively.

SIZE
500 750 1000 1250 1500 1750 2000

SINGLE CIRCUIT CONNECTION. HEATER

W/O PUMP
15 15 20 25 25 25 25

W / PUMP
20 20 25 30 30 — —

PUMP ONLY
15 15 15 15 15 15 20

Figure 15. Field Wiring.

Figure 16. Models 500 – 750 Wiring Diagram.

Page 28 Figure 17. Model 1000 Wiring Diagram.

LAARS Heating Systems

TB1-1

MAIN POWER SWITCH DPDT
IGN BD #1
35 67 L1

JUMPER

L1

N1

120 VAC

IGN BD #1
35 67 S1

HSI #1
IGN BD #1 35 67 S2

IGN
BD #1
35 67 L2

IGN BD #2 35 67
L1

IGN BD #2 35 67
S1

HSI #2
IGN BD #2 35 67
S2

IGN BD #2 35 67
L2

BLOWER 1 HIGH K1 K1 LOW

HIGH

BLOWER 2

K2

K2 LOW

PUMP K3
120 VAC

2 1 P1 P2

24 VAC

1

IGN

IGN

BD #1 35 67

35 67 BD #1

24V

GND

TO PUMP
10

IGN BD #1 35 67
F1

IGN BD #1 35 67
F2

35 67 IGN 24V BD #2
K1

35 67 GND IGN
BD #2

STAGE 1

35 67 35 67

F1

F2

K2

IGN

IGN

BD #2 BD #2

INPUT STAGE 1

STAGE 1

INPUT STAGE 2

STAGE 2

LOW GAS

AUTO RESET HIGH HIGH LIMIT GAS OPTIONAL

BLOCK FLUE

MANUAL RESET HIGH LIMIT
2

STAGE 2

LOCAL/REMOTE DPDT SWITCH
STAGE 1
STAGE 2
STAGE 1

T’stat 35 67
35 67 8
T’stat

STAGE 2

Field Interlock
34 PUMP
SELECT SWITCH

FLOW SWITCH
5

Proof of Fan

1 6

Proof of Fan #2

Initiate K3 Relay Delay on Break

Press 35 67
IGN BD #1
Press 35 67
IGN BD #2

IGN BD #1 IGN BD #1

35 67 35 67

L.O.(G)

L.O.

IGN BD #2 35 67
L.O.(G)

IGN BD #2 35 67
L.O.

ALARM SILENCE

BELL

R
ALARM DRY CONTACT

TERMINAL BLOCK 1

POLE 5

POLE 6

Gas 35 67 IGN BD #1
Gas 35 67
IGN BD #2

Gas Valve stage 1
7 LIGHT
Gas Valve stage 2 9

LIGHT

H2329000D

Figure 18. Models 1250­2000 Wiring Diagram.

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters

Page 29

Figure 19. Models 500­750 Connection Diagram.

Page 30

LAARS Heating Systems

Figure 20. Size 1000 Connection Diagram.

Figure 21. Sizes 1250­2000 Connection Diagram.

COLOUR LEGEND
BK-BLACK W-WHITE R-RED Y-YELLOW BL-BLUE BR-BROWN O-ORANGE G-GREEN P-PURPLE GR- GREY
WIRING
24V
120V
OPTIONAL WIRING
24V

WIRES NOT INSTALLED ON PUMP MOUNTED UNITS.
BK/W
PUMP BK/W

TERMINAL BLOCK 1

ALARM ALARM
G W

6
5
4 L2 LOAD 3G 2 N2 1 L2

OPTIONAL LWCO 2 1 P1 P2

BL 1 2 Y
3

4
RELAY, DELAY ON BREAK

6

R

SWITCH P/W

BK/W

MAIN POWER

BK/W

YY BL

HIGH

GAS

BL

BL

LOW GAS

AUTO RESET HIGH LIMIT OPTIONAL

BLOCK FLUE

MANUAL RESET HIGH LIMIT

BL

BL

BL/W R/BK

YY BK/W

FLOW SWITCH

Gas Valve 1
Gas Valve 2
Y/R Y/BK

P PROOF OF FAN LIGHT BL/BK
Y/BK STAGE 1

DPDT SWITCH

LOCAL/REMOTE

STAGE 2

R/W

BL BL BL/W BL P/W GR/P P/W BR/BK
BR/R
BK R/BK
R

Fuse

P BL BL

1

P/BK

1

2

3

FIELD

INTERLOCK 4

5

GR

6

GR/BK

7

BR/BK

8R 9 BR/R 10 Y 10

INPUT STAGE 1 G STAGE 1
INPUT STAGE 2 STAGE 2

TRANSFORMER BK
24V 120V W
R/BK
PROOF OF FAN #2
GR/R (GR/W)

BL/W

AQUASTAT BL/BK

STAGE 1 R/BK

BL/R

STAGE 2

ALARM

DRY

CONTACT

Y

O

Y

BELL

Y

LIGHT

BL

BL

BL

ALARM SILENCE BL

O

O/BK O/R

BL/BK BL/R

JUMPER ONLY INSTALLED ON PUMP MOUNTED UNITS (1250 & 1500). REMOVE JUMPERS FOR SEPARATE PUMP POWER SOURCE (L2/N2)

BK/W BK BK
W W W G
G W BK

1 BK
2 BK 3 BK/W 4 BK 5W 6 W/BK 7 W/BK 8W 9G
10 FIELD G 11 FIELD N 12
FIELD L1

GR/BK

S1 L1

Fenwal

F1

L2 GR S2

F2

G BL/BK
O/BK

Remote Sense
Ground
24V Gas Valve Pressure Switch lockout indicator (G) T-stat lockout indicator

GR/BK S1 L1 L2
GR S2

Fenwal

F1 F2 BL/R

G
BL/R BR/R GR/R P/R
R O/R

Remote Sense
Ground 24V Gas Valve Pressure Switch lockout indicator (G) T-stat lockout indicator

G W/BK N BL/BK LOW

BR/BLK

HIGH

BLOWER 1

RELAY 1 2 43
BK 6 5
87

BR/R

BL/BK

Y

BR/BK

G W N

BL/R LOW

BR/R

HIGH

BLOWER 2

RELAY 2

2 BR/R 4
BK 6

3 5 BR/BK

87

BL/R

Y

H2329000F

Page 31

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters

Page 32

LAARS Heating Systems

6.H.1 Field Wiring Main Power: The main field wiring connection
points are located inside the line voltage connection/ field wire area. Single circuit 120-volt units will be field connected at the main terminal block labeled “120V (L1)”, “NEUTRAL” and “GROUND”. See Figure 15 for over current protection ratings.
Sizes 1750, 2000 (and those which have been field retrofitted to electrically separate the pump and heater) require two 120-volt circuits. The heater circuit is found on the main terminal block and denoted as “120V (L1)”, “NEUTRAL” and “GROUND”. The pump circuit is located on terminal block 1 and is denoted as “120V (L2)”, “N2 (PUMP MTD)”, “GROUND 2 (PUMP MTD)”. See Figure 15 for over current protection ratings.
External Pumps: All non-pump-mounted MT2 units have an internal (dry) contact rated for 20Amps. A field-supplied pump can be connected directly to this contact if it does not draw more than 20 Amps. If more current is required, a separate pump contactor must be installed.
To utilize this internal pump contact, supply 120 volt single-phase power to the terminal marked “120V (L2)” and supply the pump using the terminal marked “L2 LOAD (EXT. PUMP)”.
NOTE: This pump control is equipped with a delay on break typically set for 3 minutes, but can be adjusted between 0.1 and 10 minutes.
Field Interlocks: To install other field-wired devices to interlock with the boiler (tank stats, louver switches, flow switches, etc.), remove the jumper between terminals 3 and 4 and wire the device in series across these terminals. These terminals are located in the upper main control panel.
External Control Wiring: These terminals are located in the upper main control panel.
Optional Alarm Contacts: As an option, this unit is available with an alarm kit. This alarm kit contains a dry contact for up to 120V which is available within the 120V field wiring panel. These terminals will be clearly labeled “Alarm” and are rated up to 10 amps.
6.I External Staging Control Wiring
WARNING
Improper field wiring may result in fire or explosion which can cause property damage, severe injury, or
death. Make only wiring connections which are in accordance with the Installation and Operation manual.
AVERTISSEMENT
Un câblage incorrect lors de l’installation peut causer un incendie ou une explosion pouvant entraîner des dommages matériels, de graves blessures ou la mort. Ne faire seulement que les connexions
conformes au Manuel d’installation et d’exploitation.

If controlling the stages of the MT2 from an external source (multiple boiler control, BAS, etc.), wire Stage 1 to the terminals marked “Input Stage 1” and “Stage 1”, and wire Stage 2 to the terminals marked “Input Stage 2” and “Stage 2”. The “Local/Remote” selector switch above the terminal strip must be placed in the “Remote” position for the external controller to manage the staging.
If it is intended to use the MT2’s on-board 2- stage controller, no extra wiring is necessary. Ensure the Local/ Remote selector switch is in the “Local” position.
SECTION 6 Operating Instructions
6.A Sequence of Operation Upon initiation of the main power switch, 120V will
be sent to multiple items. Among these are the open contact fan relays, open contact ignitor relay, open contact pump relay, ignition control module(s) and open contact lock out indicators (the optional alarm package uses this). In addition to these, 24V will travel through the optional gas pressure switches and optional auto reset high limit and boiler control relays. The 24V will then travel through the block flue switch and the manual reset high limit to the temperature controller.
Upon a call for heat from the MT2’s internal control or an external staging control, 24V travels through the field interlock (if closed) and then to the ignition control(s) “T-stat” terminal (500-750 models are equipped with one ignition control and models 10002000 are equipped with two ignition controls).
When “T-stat” on an ignition control is energized, its fan will energize and the ignition control will seek signal from the “pressure circuit”. The pressure circuits consist of the flow switch and proof of fan.
Models 500-1,000 calls for fan, fan prove, initiate pump then prove flow, after which “pressure circuit” has been satisfied.
Models 1250-2000 calls for pump, proof of flow, initiate fan then prove fan, after which “pressure circuit” has been satisfied. The fan prove will only occur for the active stage that has been called.
When pressure circuit has been satisfied, proving

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters

Page 33

combustion air and adequate water flow, the hot surface igniter will initiate. The ignition control checks that the
igniter current reached a predetermined level then will dwell momentarily. When dwell time is complete the gas valve will open.
After a 4-second trial for ignition, the igniter switches off. Unless a flame is detected by the flame sensor (a minimum value of 0.4µA), the gas valve will close and The ignition module will either attempt ignition again (up to three times) or will lock out if the optional lockout ignition module is used.
If flame is sensed, the burner will continue to fire as long as there is a call for heat and adequate flame signal. If there is a subsequent loss of flame signal, the burner will attempt re-ignition up to three times (only once if optional lockout ignition is used.) When the call
for heat is satisfied, the gas valves(s) close and the blowers continues to run for 30 seconds.
The pump will continue to run for 0.1 to 10 minutes, depending on what the pump time delay has been set to. Model sizes 1,000-2,000 have two ignition controls that control the individual stages. If one ignition control
should fail for any reason, the remaining module can operate its burners independently. (Note that if a single blower is disabled on units 1250-2000, the other fan will
continue to operate and safely allow the boiler to run
with a single stage.)
6.B Filling the System
1. Ensure the system is fully connected. Close all bleeding devices and open make-up water valve. Allow system to fill slowly.
2. If make-up water pump is employed, adjust pressure switch on pumping system to provide a minimum of 12 psi (81.8 kPa) at the highest point in the heating loop.
3. If a water pressure regulator is provided on the make-up water line, adjust the pressure regulator to provide at least 12 psi (81.8 kPa) at the highest point in the heating loop.
4. Open bleeding devices on all radiation units at the high points in the piping throughout the system, unless automatic air bleeders are provided at such points.
5. Run system circulating pump for a minimum of 30 minutes with the boiler shut off.
6. Open all strainers in the circulating system, check flow switch operation, and check for debris. If debris is present, clean out to ensure proper circulation.
7. Recheck all air bleeders as described in Step 4. 8. Check liquid level in expansion tank. With the
system full of water and under normal operating pressure, the level of water in the expansion tank should not exceed ¼ of the total, with the balance filled with air. 9. Start up system according to the procedure in this manual. Operate the entire system, including the

pump, boiler, and radiation units for one (1) hour. 10. Recheck the water level in the expansion tank. If
the water level exceeds ¼ of the volume of the expansion tank, open the tank drain, and drain to that level. 11. Shut down the entire system and vent all radiation units and high points in the system piping, as described in Step 4. 12. Close make-up water valve and check strainer in pressure reducing valve for sediment or debris from the make-up water line. Reopen make-up water valve. 13. Check gauge for correct water pressure and also check water level in the system. If the height indicated above the boiler insures that water is at the highest point in the circulating loop, then the system is ready for operation. 14. Refer to local codes and the make-up water valve manufacturer’s instructions as to whether the make-up water valve should be left open or closed. 15. After placing the unit in operation, the ignition system safety shutoff device must be tested. First, shut off the manual gas valve, and call the unit for heat. After the pre-purge and ignitor heat-up time, the main gas terminals will be energized, attempting to light, for four (4) seconds, and then
1 Difference between the temperatures at which the two switch-
es make R-W. Adjustable from 3°F to 10°F (1.7°C to 5.6°C) on standard models, or from 3.6°F to 12°F (2.0°C to 6.7°C); 55°F to 175°F (13°C to 79°C) models.
2 Two DPDT switches operate in sequence. Each switch differ-
ential is fixed at approximately 3°F (1.7°C) on standard models, or 3.6°F (2.0°C); 55°F to 175°F (13°C to 79°C) models.
Figure 22. Honeywell L8008G.

Page 34

LAARS Heating Systems

will de-energize. The unit will go into lockout mode. Second, turn the power off and then on again, open the manual gas valve and allow the unit to light. While the unit is operating, close the manual gas valve and ensure that power to the main gas valve has been cut. 16. Within three (3) days of start-up, recheck all air bleeders and the expansion tank as described in Steps 4 and 8 above.
Important: The installer is responsible for identifying to the owner/operator the location of all emergency shutoff
devices.
WARNING
Do not use this unit if any part has been under water. Immediately call a qualified service technician to inspect the unit and to replace any part of the control
system and any gas control that may have been under water.
6.C Operating Temperature Control
All of these units are equipped with a two-stage aquastat. To utilize this mounted controller be sure to have the “Local/Remote” selector switch to “Local”. Set the controller to the desired operating set point. The controller has an interstage differential that can be adjusted from 3°F to 10°F. This allows the user to have some control over how stage 2 and stage 1 call for heat (see Figure 22).
Because the controller senses inlet water and the manual reset high limit senses outlet water, the high limit should be set 40-50°F higher than the controller, to avoid nuisance lockout of the manual reset high limit.
6.D External Boiler Operations
If controlling the stages of the MT2 from an external source (multiple boiler control, BAS, etc) the “Local/Remote” selector switch above the terminal strip must be placed in the “Remote” position. In this mode, the controller that is mounted on the MT2 will no longer have control of the unit. The 24V from the unit waits at the input terminal, and the external control switches this 24V from the input terminal to the stage terminal.
6.E Limit Controls
The manual reset high limit control is provided as standard equipment on all heaters. An additional automatic reset switch is optional.A high limit temperature-sensing bulb is always located in the heater outlet. Burners will automatically shut down whenever overheating occurs.

6.F Operating the Burner and Set Up
6.F.1 Set Up for 0 to 2500 Feet Altitude This unit utilizes a modular design to achieve its
stage-firing. The setup must be checked before the unit is put in operation. Problems such as failure to start, rough ignition, strong exhaust odors, etc. can be due to improper setup. Damage to this unit resulting from improper setup is not covered by the limited warranty. 1. Using this manual, make sure the installation
is complete and fully in compliance with the instructions.
2. Determine that the unit and system are filled with water and all air has been bled from both. Open all valves.
3. Observe all warnings on the Operating Instructions label and turn on gas and electrical power to unit.
4. Switch on the power switch located on the right side of the unit.
5. This unit will enter the start sequence, as long as
there is a call for heat. The blower and pump come on for pre-purge, then the ignitor warm-up sequence starts and after the ignitor warm-up is complete and all safety devices are verified, the gas valves open. If ignition doesn’t occur, check
that there is proper gas supply. Wait 5 minutes and start the unit again. During initial start up, air in the
gas line may cause this unit to “lock out” during the first few trials for ignition. Depending on the ignition modules installed, the manual reset button on the ignition modules may need to be depressed to restart the unit.
6. When the unit is running, the supply gas pressure
must be checked. Inlet gas pressure must not exceed 13″ W.C. (3.2kPa). The minimum inlet gas pressure is 5″ W.C. (1.2kPa). 7. Once the inlet gas pressure is verified, the outlet gas pressure from each valve (manifold gas pressure) must be checked, and adjusted, if necessary. The manifold gas pressure must be 2.5″ W.C. (0.62kPa). 8. Complete the setup by checking the CO2 at the outlet of the unit. The CO2 should be 8% for natural gas, or 9.2% for propane. 9. After placing the unit in operation, the Burner Safety Shutoff Device must be tested. (a) Close gas shutoff valve with burner operating. (b) The flame will go out and blower will continue to
run for the post purge cycle. One additional
attempt to light will follow. Ignition will not occur as the gas is off. The ignition control will lockout, and will have to be reset before the unit will operate.
(c) Open gas shutoff valve. Restart the unit. The ignition sequence will start again and the
burner will start. The unit will return to its previous mode of operation.

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters

Page 35

NOTE: Model sizes 1000­2000 have two ignition controls and two ignitors, which work independently
of one another. If the ignition control for stage 1 fails to properly light the main burners for that stage, the second ignition control will still be active, and will be able to energize stage 2. This, of course, will only occur upon call for stage 2 and if all other safety devices
confirm that the unit will run in a safe condition.
6.F.2 High Altitude Adjustment and Set Up These units may be operated at high altitude (7700
ft., 2347 m) with a reduction in output of approximately 10%. At altitudes of less than or more than 7700 ft. (2347 m) the unit will perform equally as well, but with differing reductions in output. At elevations higher than 7700 ft. (2347 m) the reduction in output will exceed 10% and at elevations below 7700 ft. (2347 m) it will be less than 10%. High altitude adjustment must not be made on units operating at elevations below 2500 ft. (762 m).
No orifice changes are required to adjust this unit for high altitude. High altitude adjustment is accomplished by adjustment of the gas valve manifold pressure and the air shutter(s). The required instruments used to assist in these adjustments are a CO2 or O2 Analyzer and a U-Tube Manometer or other device capable of reading a pressure of 2.5-3.0 inches W.C. (0.62-0.75 kPa).
Start the adjustment process by checking the CO2 in the “as installed” condition. Adjust the air shutter(s) so that the CO2 is about 8% or the O2 is about 6.8% for units operating on Natural Gas. For units operating on LP Gas adjust the air shutter(s) so that the CO2 is about 9.2% or the O2 is about 6.8%. Units with two blowers should be adjusted so that the air shutters below each blower are open the same amount.
Once the CO2 or O2 has been set, the manifold pressure may be adjusted. Remove the 1/8 NPT plug from the lower side of the gas valve that is to be set and install a fitting, hose and manometer. Start the unit and observe the manifold pressure. Manifold pressure must be adjusted to 3.0 in. W.C. (0.75 kPa) (for high altitude only, standard operating pressure is 2.5 in. W.C. (0.62 kPa)). It is adjusted by removing the slotted cap on the gas valve and turning the adjustment screw (beneath the cap) clockwise to increase pressure and replaced after
the adjustments have been completed and the fitting, hose and manometer have been removed and the 1/8″ plug has been replaced. Repeat this process until all gas valves have been set. Note: The pressure can be set only when the unit is operating and only when the particular
gas valve being adjusted is energized by a call for heat from the staging control.
After all of the gas valve manifold pressures have been set, the CO2 or O2 must be reset. CO2 or O2 will have changed when the manifold pressure was adjusted. Open the air shutter(s) to reduce the CO2 or O2 to the values achieved previously.

The procedure is complete when all gas valves are adjusted to a manifold pressure of 3.0 in. W.C. (0.75 kPa) and the CO2 is adjusted to 8.0% for Natural Gas units or 9.2% for LP units (to be checked only at full fire). When using an O2 analyzer, the correct O2 is 6.8% for both Natural Gas and LP units.
CAUTION
Should any odor of gas be detected, or if the gas burner does not appear to be functioning in a normal
manner, close main shutoff valve, do not shut off switch, and contact your heating contractor, gas
company, or factory representative.
6.G Shutting Down the Unit
1. Switch off the main electrical disconnect switch. 2. Close all manual gas valves. 3. If freezing is anticipated, drain this unit and be sure
to also protect building piping from freezing. This step to be performed by a qualified service person.
6.H To Restart the Unit
If drained, follow Section 6.B in this manual for proper filling and purging.

1. Switch off the main electrical disconnect switch. 2. Close all manual gas valves. 3. WAIT FIVE (5) MINUTES. 4. Set the aquastat or thermostat to its lowest setting. 5. Open all manual gas valves. 6. Reset all safety switches (pressure switch, manual reset high limit, etc.). 7. Set the temperature controller to the desired temperature setting and switch on electrical power.
2. Burner will go through a prepurge period and ignitor warm-up period, followed by ignition.

Page 36

LAARS Heating Systems

SECTION 7 Maintenance
7.A System Maintenance
1. Lubricate the system water-circulating pump, if required, per the instructions on the pump.
2. If a strainer is employed in a pressure reducing valve or the piping, clean it every six months.
3. Inspect the venting system for obstruction or leakage at least once a year. Periodically clean the screens in the vent terminal and combustion air terminal (when used).
4. Keep the unit area clear and free from combustible materials, gasoline, and other flammable vapors and liquids.
5. If the unit is not going to be used for extended periods in locations where freezing normally occurs, it should be isolated from the system and completely drained of all water. All systems connected to it should also be drained or protected from freezing.
6. Low water cutoffs, if installed, should be checked every 6 months. Float type low water cutoff should be flushed periodically.
7. Inspect flue passages, and clean with brushes/ vacuums, if necessary. Sooting in flue passages indicates improper combustion. Determine the cause and correct.
8. Inspect the vent system and air intake system, and if the vent system is Category III, ensure that all joints are sealed properly. If joints need to be resealed, completely remove existing sealing material, and clean with alcohol. Apply new sealing material, and re-assemble.
7.B Maintenance and Component Description
Only genuine OEM replacement parts should be used.
CAUTION
Label all wires prior to disconnection when servicing controls. Wiring errors can cause improper and dangerous
operation. Verify proper operation after servicing.
See Figure 5 for location of gas train components. The gas and electric controls on the unit are engineered for long life and dependable operation, but the safety of the equipment depends on their proper functioning. It is strongly recommended that a qualified service technician inspect the basic items listed below every year. a. Ignition controls b. Ignitors c. Water temperature control d. Automatic gas valve e. Pressure switches

f. Blowers
7.B.1 Burners Close main manual gas valve before proceeding.
Checking the burners for debris – Remove the ignitor inspection panels(s) and ignitor(s) and inspect the burners through the ignitor hole(s) using a flashlight to illuminate. If there is any indication of debris on the burners that are visible, all the burners will need to be inspected more thoroughly. Remove the screws from around the front of the air box (large panel from which the ignitor inspection panel(s) were removed), and remove the large panel. Remove the gas manifold assemblies and the burner panels. Inspect the burners. Clean burners, if necessary, by blowing compressed air from the outside of the burners into the center of the burner. A dirty burner may be an indication of improper combustion or dirty combustion air. Determine the cause, and correct. Replace the burners in the reverse order
7.B.2 Filter The filter used in the this unit is washable with an
83% arrestance. Since the filter is washable, it will only need replacement when unwashable, deteriorated or damaged. If filter replacement is needed, it should only be replaced with a factory part. Inspect the air filter. If there is debris on the air filter, remove it from the filter box, and wash it with mild soap and water. Ensure that the filter is completely dry before re- installing, in reverse order.
7.B.3 Gas Valves The gas valves are designed to operate with supply
pressures of 4-13 inches w.c. (1.0 to 3.2 kPa). To remove a valve, shut off 120-volt power and the
manual gas shutoff valve. Remove the top front panel from the unit. Disconnect the wires to the valve. Disengage the flanged fitting before and after the valve, and remove the valve. Re-install in reverse order. Ensure o-rings are properly installed for both inlet and outlet. Turn on manual gas shutoff valve and 120 volt power and check operation and tightness of gas valve connections.
7.B.4 Manual Reset High Limit Control The high limit switch is manual reset switch with
an adjustable set point, up to 240°F (116°C) on boiler models and 200°F (93°C) on water heater models and boilers ordered with low temperature controls. To replace the switch, shut off the 120-volt power to the unit. Remove the cover from the switch to access the mounting screws. Remove the screws, and pull the switch off the control panel. Remove the capilliary and bulb from the thermal well located in the header. Replace in reverse order.

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters

Page 37

7.B.5 Temperature Control The temperature control is a Honeywell L6008.
To replace the control, shut off the 120-volt power to the unit. Remove the cover from the control panel, and remove the mounting screws to remove the controller. Replace in reverse order.
7.B.6 Ignition Controls The ignition controls ensure the proved interrupted-
type ignition system. They control the hot surface ignitors and prove that the flame signal is appropriate for powering the gas valves. It also controls the blower’s pre-purge and post-purge. Model sizes 500 and 750 have one ignition control. Sizes 1000 to 2000 have two ignition controls. On sizes up to 750, one ignition control controls stages 1 and 2. On unit sizes 1000­2000, one ignition control is for stage 1, and the other is for stage 2.
To replace a control, shut off the 120-volt power to the unit. Remove the cover from the control panel. Remove the electrical connectors from the ignition control. Take out the controller’s mounting screws, and pull the controller out. Replace in reverse order.
7.B.7 Ignitors/Sensor The ignitor/sensor used are 120v “hot surface”
type. They are energized whenever there is a call for heat and switched off when ignition is established and flame has been sensed. Model sizes 500 and 750 have one ignitor/sensor. Sizes 1000 to 2000 have two ignitor/ sensors. To replace the ignitor/sensor, shut off the 120-volt power to the unit, remove the ignitor access panel, disconnect the Molex connector, remove the two mounting screws on the ignitor/sensor flange and pull the ignitor out. ((Hot Surface) Ignitor and the Flame Sensor are the same items). Install in reverse order, always using a new ignitor gasket with the replacement ignitor.
CAUTION
Ignitor gets hot.
7.B.8 Transformer The transformer is not capable of supplying control
voltage for external devices such as zone valves, which must have their own separate power supply. Should a transformer need replacing, shut off the 120volt power. Unplug the transformer wires, remove the mounting screws and remove the transformer. Replace transformer in the reverse order.
7.B.9 Blowers The combustion air blowers bring the combustion
air for the this unit from the upper chamber to the lower chamber. Mixing of the gas and air occurs in the burners. Sizes 500, 750 and 1000 each have one blower, and

sizes 1250 to 2000 each have two blowers. If a blower change is required, turn off the 120-volt power and gas supply to the unit. Remove the front panel. Disconnect the blower’s wire harness. Remove the screws at the blower flange, and pull the blower out. Replace blower in reverse order, ensuring that all joints are made correctly. After replacement, ensure that the unit operates properly, by following the set-up procedure in this manual.
7.B.10 Flow Switch This unit uses a paddle-type flow switch to ensure
that the unit has water flow before ignition is allowed.
7.B.11 Heat Exchanger Coil
WARNING
Black carbon soot buildup on a dirty heat exchanger can be ignited by a random spark or flame, thereby creating a risk of fire or explosion.. To prevent this from happening, dampen the soot deposits with a wet brush or fine water spray before servicing the heat exchanger.
This unit has a pre-mixed burner system. These systems provide the burners with sufficient air for complete combustion, and black carbon sooting is seldom experienced. If sooting is suspected, view ports for inspection of the heat exchanger are provided on the right side of the boiler. They are located below the headers, and are accessed by opening the small round cover that is attached by one screw. In the unlikely event that there is a buildup of black carbon soot or other debris on the heat exchanger, clean per the following:
1. Disconnect the electrical supply to the unit.
2. Turn off the gas supply by closing the manual gas valve on the heater.
3. Disconnect and remove the wires, conduit and sensors from all components that are attached to the inlet/outlet header.
4. Isolate the heat exchanger from the water supply.
5. Disconnect the header flanges from the inlet and outlet.
6. Allow the heat exchanger to drain. Remove the front cover(s) by removing the rubber access strip(s) and the retaining screws. Remove the venting and remove the top, by removing the screws that attach the top to the side panels. Remove the side panels. Remove the front lower panels sealing the combustion area. To remove the gas train, disconnect the unions located below the intermediate pan and the field installed union located outside the cabinet, and pull up, bringing the union end connectors through the grommets in the intermediate pan. To remove the intermediate pan, remove the slide out control assembly and blower(s) to reveal the screws. Remove the screws holding the intermediate pan, and lift up to remove it. The heat

Page 38

LAARS Heating Systems

SECTION 8 Trouble Shooting

exchanger has integral metal sections attached, which connect to the frame of the boiler. Locate and remove the screws along the front, rear and bottom of the integral metal sections, and remove the heat exchanger and metal sections by lifting up. On the larger units, a center heat exchanger support must be unbolted before it can be removed.
7. Remove the heat exchanger from the unit. Note: The heat exchangers are heavy and may require two people to remove to avoid personal injury.
8. Clean the heat exchanger: A light accumulation of soot or corrosion on the outside of the heat exchanger can be easily removed. Use a wire brush to remove loose soot and scale from the heat exchanger. Do not use water or compressed air for cleaning.
9. Note: While the heat exchanger is out of the unit, inspect the firewall refractory insulation. Replace if necessary.
10. Inspect the inside of the copper tubes for scale buildup. Scale can build up on the inner surface of the heat exchanger tubes, which can restrict water flow. If the tubes show signs of scaling, clean the internal surface. The manufacturer offers a tube cleaning kit, part number R0010000.
11. Reassemble in the reverse order, and check the units operation after start-up.
NOTE: The Warranty does not cover damage caused by lack of required maintenance, lack of water flow,
or improper operating practices.

8.A Resolving Lockouts
There are many causes of lockouts. The three most common causes are: (1) inadequate gas supply, (2) poor combustion, (3) ignitor failure. 1. Inadequate gas supply: Before proceeding, ensure
that the gas supply has not been shutoff or the LP tank (LP boilers) is not empty.
If your boiler is equipped with the optional gas pressure switches, then the Low Pressure switch might have tripped and will need to be reset.
Then, restart the boiler and observe the operational cycle. After a 15-second fan pre-purge, the ignitor will heat up for 20 seconds, and then the unit will light. If it does not, check the gas supply pressure to the unit, after resetting the unit and attempting another start-up. The gas pressure to the unit must be above 5″ W.C. (1.2kPa) throughout the entire start-up cycle. If it is not, correct the supply problem (check gas valves or supply piping). If the supply pressure is adequate, consult the factory for assistance. 2. Poor combustion: Poor combustion should be suspected if there is a strong flue gas odor. The odor may result from an improper gas/air ratio (high or low O2 or CO2). These units operate best with 45% excess air (8% CO2 on natural gas, 9.2% CO2 on LP). Check the CO2 of the unit and adjust if necessary. 3. Ignitor failure: If the boiler goes through a normal start cycle but combustion does not occur, ignitor failure should be suspected. Check the ignitor by unplugging the ignitor plug and measuring the ignitor resistance. It should be 50-80 ohms at room temperature. If the resistance is not 50-80 ohms, replace the ignitor. If the resistance is correct, reset the boiler and check for 120 VAC at the ignitor plug during the start cycle. If there is no voltage, replace the faulty ignitor wire harness or the ignition control.

8.B Delayed Ignition — Possible Causes
A defective burner can cause a delayed ignition. If the gas supply pressure is proper and the gas valves are
functioning properly, then burners should be inspected. There should be no distortion or perforations in the burners outside of the active burner port area. Replace if indicated.

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters

Page 39

8.C Short Cycling — Boiler
Because this unit is a stage-fired boiler, and its input will decrease when there is a reduction in heating load, short cycling is greatly reduced. If the heating load drops below the minimum input of the boiler for an extended period, the boiler will have a tendency to short cycle. This can be a symptom of improper control strategy or setpoints, or a load distribution problem. Contact your manufacturers representative to discuss possible remedies.
8.D Short Cycling — Water Heater
Short cycling will generally occur only in combination space heating and water heating applications when the water heater is operating in the space-heating mode. Because the unit is a stage-fired water heater and its input will reduce when there is a reduction in heating load, short cycling is greatly reduced. If the heating load drops below the minimum input of the water heater for an extended period, the water heater will have a tendency to short cycle. If short cycling is frequently experienced, regardless of the control’s attempt to limit it, the heating load should be redistributed to control it.
If short cycling occurs in a water heater application, it is probably caused by undersized piping between the water heater and the storage tank or by some other factor that restricts proper water flow through the water heater. The cause should be determined and corrected.

8.E High Gas Consumption
Units operating with an improper air/fuel ratio are very inefficient and consequently, have very high gas consumption. Because efficiency is high when the CO2 is high (or O2 is low), units operating with low CO2 or high O2 (especially LP units) consume more gas. Adjust the CO2 or O2 for optimum efficiency. If no combustion analyzing equipment (CO2 or O2) is available then a proper adjustment of the air/fuel ratio (CO2 or O2) cannot be accomplished. However, by briefly sniffing the flue gases it is possible to determine if the CO2 or O2 is within the proper range. No significant flue gas odor should be detected when combustion is proper. A strong piercing smell indicates poor combustion and generally a lean mixture – low CO2 or high O2 . The CO2 should be 8% at high fire. To check the CO2, first verify that the supply gas pressure is within 5″ to 13″ w.c. (1.2 to 3.2 kPa) With the unit running with all stages firing, set the air box pressure to 1.5″ w.c. (0.37 kPa) (as a starting point), by adjusting the air shutter(s) at the bottom of the fan(s). Check the CO2, and adjust the air shutters if further adjustment to the CO2 is needed. Sizes 1250 to 2000 have two blowers and two air chambers (boxes). The pressure of each air box must be equal when the final adjustment is made.

SECTION 9 Replacement Parts
Only genuine OEM replacement parts should be used.
9.A General Information
To order or purchase parts for this unit, contact your nearest Manufacturers Representative or Distributor. See back cover for website.
9.B Parts List – see next pages.

IItem
1 2A 2B 3A 3B 4 5 6 7 8 9 10 11
12A 12B 12C 14
16 17 18 19 20 21 22
23 24 25 26 27
28 29 30 31

Description
Sheet Metal Components ­ See Figure 23 Panel, Jacket, Front Panel, Jacket, Side, Lower Left Panel, Jacket, Side, Lower Right Panel, Jacket, Side, Lower Left Panel, Jacket, Side, Lower Right Panel, Side, Top Left, Jacket Panel, Side, Top Right, Jacket Panel, Rear, Jacket Panel, Top, Jacket Weldment, Vent Plate Weldment, Housing, Air Inlet/Filter Panel, Access, Filter Filter, Combustion Air
Pump Housing Right Side Pump Housing Left Side Pump Housing Cover Cover, Pipe, Gas Manifold

Size 500
5F3320 5F3420 5F3421 5F3520 5F3521 5F3400 5F3501 5F3220 5F3021 5F3100 5F3800 5F3701 A2088700
(1)
5C3018 5C3019 5C3020 5F3304
(2)

Internal Components ­ See Figure 24 Assembly, Base Panel, Front, Combustion Chamber Panel, Rear, Combustion Chamber Panel, Top, Combustion Chamber Weldment, Chamber, Left Side, Bottom Weldment, Chamber, Right Side. Bottom Panel, Chamber, Left/Right Side, Top
Assembly, Sight Glass Panel, Left Side, Air Box Panel, Right Side, Air Box Panel, Access, Air Box Cover, Access Panel, Air Box
Divider, Chamber, Upper, Air Box Divider, Chamber, Lower, Air Box Divider, Front Chamber, Combustion Chamber Assembly, Exhaust Stack

5F1020 5F2003 5F2006 5F2001 5C2602 5C2202 5C2002
(2) 10956000
5F2015 5F2016 5F2004 5F2005
(1)
5F2027

Size 750
7F3320 5F3420 5F3421 5F3520 5F3521 5F3400 5F3501 7F3220 7F3021 7F3100 5F3800 5F3701 A2088700
(1) 5C3018 5C3019 5C3020 5F3304
(2)
7F1020 7F2003 7F2006 7F2001 5C2602 5C2202 5C2002
(2) 10956000
5F2015 5F2016 7F2004 5F2005
(1)
7F2027

Size 1000
10F3320 5F3420 5F3421 5F3520 5F3521 5F3400 5F3501 10F3220 10F3021 7F3100 10F3800 5F3701 A2088700
(1) 5C3018 5C3019 5C3020 10F3304
(2)
10F1020 10F2003 10F2006 10F2001 5C2602 5C2202 5C2002
(2) 10956000
5F2015 5F2016 10F2004 5F2005
(1)
7F2027

Size 1250
12F3320 5F3420 5F3421 5F3520 5F3521 5F3400 5F3501 12F3220 12F3021 12F3100 12F3800 12F3701 A2088700
(2) 5C3018 5C3019 5C3020 20F3304
(2)
12F1020 12F2003 12F2006 12F2001 5C2602 5C2202 5C2002
(2) 10956000
5F2015 5F2016 12F2004 5F2005
(2) 15F2005 15F2002
12F2027

Size 1500
15F3320 5F3420 5F3421 5F3520 5F3521 5F3400 5F3501 15F3220 15F3021 12F3100 12F3800 12F3701 A2088700
(2) 5C3018 5C3019 5C3020 20F3304
(2)
15F1020 15F2003 15F2006 15F2001 5C2602 5C2202 5C2002
(2) 10956000
5F2015 5F2016 15F2004 5F2005
(2) 15F2005 15F2002
12F2027

Size 1750
17F3320 5F3420 5F3421 5F3520 5F3521 5F3400 5F3501 17F3220 17F3021 12F3100 12F3800 12F3701 A2088700
(2) 5C3018 5C3019 5C3020 20F3304
(2)
17F1020 17F2003 17F2006 17F2001 5C2602 5C2202 5C2002
(2) 10956000
5F2015 5F2016 17F2004 5F2005
(2)
20F2002 12F2027

Size 2000
20F3320 5F3420 5F3421 5F3520 5F3521 5F3400 5F3501 20F3220 20F3021 20F3100 20F3800 12F3701 A2088700
(2) 5C3018 5C3019 5C3020 20F3304
(2)
20F1020 20F2003 20F2006 20F2001 5C2602 5C2202 5C2002
(2) 10956000
5F2015 5F2016 20F2004 5F2005
(2)
20F2002 12F2027

LAARS Heating Systems

Page 40

Item Description

32

Assembly, Copper Tube, Heat Exchanger

Assembly, Cupro-Nickel, Heat Exchanger

33

Tile, Side (Left and Right)

34

Tile, Front

35

Tile, Front, Left Side

36

Tile, Front, Right Side

37

Tile, Front, Center

38

Tile, Rear

39

Tile, Rear, Left Side

40

Tile, Rear, Right Side

41

Tile, Rear, Center

42

Tile, Bottom

43

Tile, Bottom, Left Side

44

Tile, Bottom, Right Side

45

Tile, Bottom, Center

Gas Train Components ­ See Figure 24

46

Blower

47

Weldment, Blower Mount

47A Assembly, Blower Damper

48

Manifold, Gas Supply

49

Valve, Ball, Manual Shutoff

50

Valve, Gas, Combination

50A O-Ring

51A Weldment, Pipe, Gas Valve/Ball Valve

51B 4″ Nipple, black

51C Union

52

Valve, Ball, Manual Shutoff, Secondary

53

Manifold, 3 Burner/Orifice, Left

Size 500 5C4000 5C4020 T2015600 (2) T2017300 T2016200
T2015700
T2015500

Size 750 7C4000 7C4020 T2015600 (2)
T2016800 T2016300
T2017500 T2016600
T2017400 T2016500

Size 1000 10C4000 10C4020 T2015600
(2)
T2016800 T2017100
T2016600 T2016600
T2017400 T2017400

Size 1250 12C4000 12C4020 T2015600
(2)
T2016800 T2017900 T2016900
(1)
T2016600 T2018100 T2017200
(1)
T2017400 T2018000 T2015900
(1)

Size 1500 15C4000 15C4020 T2015600
(2)
T2016800 T2017100 T2016900
(1)
T2016600 T2016600 T2017200
(1)
T2017400 T2017400 T2015900
(1)

Size 1750 17C4000 17C4020 T2015600
(2)
T2016800 T2017900 T2016900
(2)
T2016600 T2018100 T2017200
(2)
T2017400 T2018000 T2015900
(2)

Size 2000 20C4000 20C4020 T2015600
(2)
T2016800 T2017100 T2016900
(2)
T2016600 T2016600 T2017200
(2)
T2017400 T2017400 T2015900
(2)

A2111900 (1)
5C5300 (1)
5C6100 V2003100 V2017600
(2) V2017500
(4) P2073600 (2) P0014700 (2) P0030400 (2)
V2000200 (2)
L2012800 (1)

A2111900 (1)
5C5300 (1)
7C6100 V2003100 V2017600
(3) V2017500
(6) P2073600 (3) P0014700 (3) P0030400 (3)
V2000200 (3)
L2012800 (2)

A2111900 (1)
5C5300 (1)
10C6100 V2003200 V2017600
(3) V2017500
(6) P2073600 (3) P0014700 (3) P0030400 (3)
V2000200 (3)

A2111900 (2)
5C5300 (2)
15C5400 (2)
12C6100 V2003300 V2017600
(5) V2017500
(10) P2073600 (5) P0014700 (5) P0030400 (5)
V2000200 (5)
L2012800 (3)

A2111900 (2)
5C5300 (2)
15C5400 (2)
15C6100 V2003300 V2017600
(5) V2017500
(10) P2073600 (5) P0014700 (5) P0030400 (5)
V2000200 (5)
L2012800 (1)

A2111900 (2)
5C5300 (2)
15C5400 (2)
17C6100 V2003300 V2017600
(6) V2017500
(12) P2073600 (6) P0014700 (6) P0030400 (6)
V2000200 (6)
L2012800 (2)

A2111900 (2)
5C5300 (2)
15C5400 (2)
20C6100 V2003300 V2017600
(6) V2017500
(12) P2073600 (6) P0014700 (6) P0030400 (6)
V2000200 (6)

Page 41

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters

Item Description Manifold, 3 Burner/Orifice, Right Manifold, 4 Burner/Orifice, Left

Size 500
L2012900 (1)

Manifold, 4 Burner/Orifice, Right

54

Assembly, 3 Burner

Assembly, 4 Burner

L2012200 (2)

55

Orifice, Gas, Natural

Orifice, Gas, Propane

56

Gasket, 3 Burner

Gasket, 4 Burner

L2013000 (6)
L2012400 (6)
S2012700 (2)

57

Ignitor, Hot Surface with Gasket

2400-286 (1)

Heat Exchanger Components ­ See Figure 25

58

Flow Switch

E0013000

59

Low Water Cutoff (optional)

E2076500

60

Gauge, Temperature/Pressure

A0079000

62

Tee, Adapter, Outlet, Cast Iron

20130001

Tee, Adapter, Outlet, Cast Iron (boiler)

Tee, Adapter, Outlet, Bronze

20150302

63

Relief Valve, Hydronic, 75 Psi

A0063300

Relief Valve, Water Heater, 125 Psi

A0001200

64

Flange, Connection, Cast Iron

10391302

Flange, Connection, Bronze

20255401

65

Gasket, Connection Flange

S0063700

(2)

66

Cover, In/Out, Glass-Lined Cast Iron

10364504

Cover, In/Out, Bronze

10364501

67

Gasket, Header/Cover

S0095100

(2)

68

Water Barrier, Inlet/Outlet

20230101

Size 750 L2012900 (1)
L2012200 (3)
L2013000 (9)
L2012400 (9)
S2012700 (3)
2400-286 (1)
E0013000 E2076500 A0079000 20130001
20150302 A0063300 A0001200 10391302 20255401 S0063700
(2) 10364504 10364501 S0095100
(2) 20230101

Size 1000
L2012600 (2)
L2012700 (1)
L2012500 (3)
L2013000 (12)
L2012400 (12)
S2012500 (3)
2400-286 (2)
E0013000 E2076500 A0079000 20130002
20150303 A0063600 A0001200 10391303 10391304 S0063700
(2) 10364504 10364501 S0095100
(2) 20230101

Size 1250 L2012900
(2)
L2012200 (5)
L2013000 (15)
L2012400 (15)
S2012700 (5)
2400-286 (2)
E0013000 E2076500 A0079000 20130002
20150303 A0063600 A0001200 10391303 10391304 S0063700
(2) 10364504 10364501 S0095100
(2) 20230101

Size 1500 L2012900
(1) L2012600
(2) L2012700
(1) L2012200
(2) L2012500
(3) L2013000
(18) L2012400
(18) S2012700
(2) S2012500
(3) 2400-286
(2)
E0013000 E2076500 A0079000 20130002
20150303 A0063600 A0064400 10391303 10391304 S0063700
(2) 10364504 10364501 S0095100
(2) 20230101

Size 1750
L2012900 (1)
L2012600 (2)
L2012700 (1)
L2012200 (3)
L2012500 (3)
L2013000 (21)
L2012400 (21)
S2012700 (3)
S2012500 (3)
2400-286 (2)
E0013000 E2076500 A0079000 20130002 20130009 20150303 A0063600 A0064400 10391303 10391304 S0063700
(2) 10364504 10364501 S0095100
(2) 20230101

Size 2000
L2012600 (4)
L2012700 (2)
L2012500 (6)
L2013000 (24)
L2012400 (24)
S2012500 (6)
2400-286 (2)
E0013000 E2076500 A0079000 20130002 20130009 20150303 A0002700 A0064400 10391303 10391304 S0063700
(2) 10364504 10364501 S0095100
(2) 20230101

LAARS Heating Systems

Page 42

Item Description

69

Baffle, Water Deflector, Inlet

70

Well, Immersion, Temperature Control

71

Cover, Return, Glass-Lined Cast Iron

Cover, Return, Bronze

72

Pump Housing, Glass-Lined Cast Iron

73

Baffle, Diffuser, Pump Housing Inlet

Size 500 10338300 E2058300 10364300 10364301 S2056900 10338400

Electrical Components ­ See Figure 26

74

Control, Gas Ignition, Three-Try (standard)

E2313900

(1)

Control, Gas Ignition, Single-Try (CSD-1 option) E2107300

(1)

75

SPDT, Toggle Switch

E0109200

75A DPDT Switch

E2056300

76

Terminal Block, 16-Position, Dual Row

E2327500

77

Switch, Hi-Limit Manual Reset (boiler)

E0015900

Controller, Temperature, 100° to 200°F,

E2217800

Manual Reset

78

Thermostat, 2-Stage, 130° to 230°F

E0093200

79

Panel, Mounting, Limits/Ignition Control

5F7001

80

Panel, Cover, High Limit/Ignition Control

5F7003

81

Panel, Access, Terminal

5F7006

82

Switch, Rocker, 30A, 125 VAC

E2343300

83

Terminal Block, 6-Position, Dual Row

E2327700

84

Terminal Block, 12-Position, Dual Row

E2342500

85

Switch, Pressure, Diaphragm, SPDT

E0240900

(2)

86

Bracket, Pressure Switch

5F7007

87

Transformer, 150 VA, 120/24V

E2310400

88

Relay, Time Delay (24 VAC)

E2077700

Delay on Break, Adj.

89

Relay, 24VAC, DPDT

E2327800

90

Panel, Mounting, LWCO Switch (optional)

91

Wire Harness #1, Fenwal

92

Wire Harness #2, Control Panel

93

Wire Harness #3, Main

94

Wire Harness #4, Local Remote SW

5F7005 E2328800 E2328900 E2329000 E2328700

NOTE: Quantity is one (1) unless otherwise indicated.

Size 750 10338300 E2058300 10364300 10364301 S2056900 10338400
E2313900 (1)
E2107300 (1)
E0109200 E2056300 E2327500 E0015900 E2217800
E0093200 5F7001 5F7003 5F7006
E2343300 E2327700 E2342500 E0240900
(2) 5F7007 E2310400 E2077700
E2327800
5F7005 E2328800 E2328900 E2329000 E2328700

Size 1000 10338300 E2058300 10364300 10364301 S2056900 10338400
E2313900 (2)
E2317300 (2)
E0109200 E2056300 E2327500 E0015900 E2217800
E0093200 5F7001 5F7003 5F7006
E2343300 E2327700 E2342500 E0240900
(2) 5F7007 E2310400 E2077700
5F7005 E2328400 E2328500 E2329100 E2328700

Size 1250 10338300 E2058300 10364300 10364301 S2056900 10338400
E2313900 (2)
E2317300 (2)
E0109200 E2056300 E2327500 E0015900 E2217800
E0093200 5F7001 5F7003 5F7006
E2343300 E2327700 E2342500 E0240900
(3) 5F7007 E2310400 E2077700
E2327800 (2)
5F7005 E2328400 E2330100 E2328600 E2328700

Size 1500 10338300 E2058300 10364300 10364301 S2056900 10338400
E2313900 (2)
E2317300 (2)
E0109200 E2056300 E2327500 E0015900 E2217800
E0093200 5F7001 5F7003 5F7006
E2343300 E2327700 E2342500 E0240900
(3) 5F7007 E2310400 E2077700
E2327800 (2)
5F7005 E2328400 E2330100 E2328600 E2328700

Size 1750 10338300 E2058300 10364300 10364301 S2056900 10338400
E2313900 (2)
E2317300 (2)
E0109200 E2056300 E2327500 E0015900 E2217800
E0093200 5F7001 5F7003 5F7006
E2343300 E2327700 E2342500 E0240900
(3) 5F7007 E2310400 E2077700
E2327800 (2)
5F7005 E2328400 E2330100 E2328600 E2328700

Size 2000 10338300 E2058300 10364300 10364301 S2056900 10338400
E2313900 (2)
E2317300 (2)
E0109200 E2056300 E2327500 E0015900 E2217800
E0093200 5F7001 5F7003 5F7006
E2343300 E2327700 E2342500 E0240900
(3) 5F7007 E2310400 E2077700
E2327800 (2)
5F7005 E2328400 E2330100 E2328600 E2328700

Page 43

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters

Page 44

12C

12B

12A

LAARS Heating Systems

Figure 23. Sheet Metal Components.

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters

Page 45

Figure 24. Internal Components

Page 46

LAARS Heating Systems

Size Size 500 750 1000 1250 1500 1750 2000

Hydronic Boiler Pump p/n A2001700 A2001700 A2001800 A2001800 A2001900 A2001900 A2109700

Figure 25. Heat Exchanger Components.

Size
500 750 1000 1250 1500 1750 2000

Soft Water A2001700 A2001700 A2001700 A2001700 A2001700 A2001900 A2109700

Water Heater Pump p/n
Normal Water A2001700 A2001700 A2001800 A2001800 A2001900 A2001900 A2109700

Hard Water A2001900 A2001900 A2001900 A2001900 A2001900 A2001900 A2109700

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters

Page 47

Figure 26. Electrical Components.

MIGHTY THERM2 Commercial Boilers and Volume Water Heaters
Notes:

H2329100L

Laars Heating Systems Company reserves the right to change specifications, components, features, or to discontinue products without notice.

Customer Service and Product Support: 800.900.9276 · Fax 800.559.1583

Headquarters: 20 Industrial Way, Rochester, NH, USA 03867 · 603.335.6300 · Fax 603.335.3355

9 Brigden Gate, Halton Hills, Ontario, Canada L7G 0A3 · 905.203.0600 · Fax 905.636.0666

www.Laars.com

Litho in U.S.A. © Laars Heating Systems 20-12 Document 1211L

References

• Laars Boilers and Water Heaters for Residential and Commercial | Laars
• P65WARNINGS.CA.GOV

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