LENNOX LGH036H4E Gas/Electric Packaged Rooftop Unit Instruction Manual

LENNOX LGH036H4E Gas/Electric Packaged Rooftop Unit

Safety

WARNING

Improper installation, adjustment, alteration, service or maintenance can cause property damage, personal injury or loss of life. Installation and service must be performed by a licensed professional HVAC installer or equivalent, service agency, or the gas supplier. Use of this unit as a construction heater or air condition-er is not recommended during any phase of construction. Very low return air temperatures, harmful vapors and op-eration of the unit with clogged or misplaced filters will damage the unit. If this unit has been used for heating or cooling of build-ings or structures under construction, the following condi-tions must be met or the warranty will be void:

•  The vent hood must be installed per these installation instructions.
•  A room thermostat must control the unit. The use of fixed jumpers that will provide continuous heating or cooling is not allowed
•  A pre-filter must be installed at the entry to the return air duct.
•  The return air duct must be provided and sealed to the unit.
•  Return air temperature range between 55°F (13°C) and 80°F (27°C) must be maintained.
•  Air filters must be replaced and pre-filter must be removed upon construction completion.
• The input rate and temperature rise must be set per the unit r ating plate.
•  The heat exchanger, components, duct system, air filters and evaporator coil must be thoroughly cleaned following final construction clean-up.
•  The unit operating conditions (including airflow, cooling op-eration, ignition, input rate, temperature rise and venting) must be verified according to these installation instructions.

NOTE – The Commonwealth of Massachusetts stipulates these additional requirements:

•  Gas units shall be installed by a licensed plumber or gas fitter only.
•  The gas cock must be “T handle” type.

The unit is certified for installation on noncombustible floors only. However, it may be installed on wood flooring, or on class A, class B, or class C material covered floors when used in horizontal discharge applications or in downflow discharge applications when mounted on a LARMF roof mounting frame. Adequate clearance shall be provided around air openings into the vestibule area. Provisions shall be made for proper operation and for combustion air and ventilation air supply. Unit must be adjusted for the temperature rise  range and within the allowable external static pressure on furnaces with a duct system as listed on unit nameplate.

United States
The unit is ETL/CSA certified for outdoor installations only at the clearances to combustible materials listed on the unit nameplate

1Unit

Clearance

| A

in.(mm)

| B

in.(mm)

| C

in.(mm)

| D

in.(mm)

| Top Clearance
---|---|---|---|---|---
Service Clearance| 48

(1219)

| 36

(914)

| 36

(914)

| 36

(914)

| Unobstructed
Clearance to Combustibles| 36

(914)

| 1

(25)

| 1

(25)

| 1

(25)

| Unobstructed
Minimum Opera- tion Clearance| 36

(914)

| 36

(914)

| 36

(914)

| 36

(914)

| Unobstructed

Note – Entire perimeter of unit base requires support when elevated above
mounting surface.
1 Service Clearance – Required for removal of serviceable parts.
Clearance to Combustibles – Required clearance to combustible material

Minimum Operation Clearance

Required clearance for proper unit operation.

1Unit

Clearance

| A

in.(mm)

| B

in.(mm)

| C

in.(mm)

| D

in.(mm)

| Top Clear- ance
---|---|---|---|---|---
Service Clearance| 60

(1524)

| 36

(914)

| 36

(914)

| 60

(1524)

| Unobstructed
Clearance to Combustibles| 36

(914)

| 1

(25)

| 1

(25)

| 1

(25)

| Unobstructed
Minimum Oper- ation Clearance| 36

(914)

| 36

(914)

| 36

(914)

| 36

(914)

| Unobstructed

Note – Entire perimeter of unit base requires support when elevated above
mounting surface.
1 Service Clearance – Required for removal of serviceable parts.
Clearance to Combustibles – Required clearance to combustible material
. Minimum Operation Clearance – Required clearance for proper unit operation.

1Unit

Clearance

| A

in.(mm)

| B

in.(mm)

| C

in.(mm)

| D

in.(mm)

| Top

Clearance

---|---|---|---|---|---
Service

Clearance

| 60

(1524)

| 36

(914)

| 36*

(914)

| 66

(1676)

| Unobstructed
Clearance to

Combustibles

| 36

(914)

| 1

(25)

| 1

(25)

| 1

(25)

| Unobstructed
Minimum Opera-

tion Clearance

| 45

(1143)

| 36

(914)

| 36**

(914)

| 41

(1041)

| Unobstructed

*242, 300H and 360 units with high static exhaust fans allow 80in. (2032mm). 242, 300H and 360 units with high static exhaust fans allow 80in. (2032mm). Note – Entire perimeter of unit base requires support when elevated above mounting surface.
1 Service Clearance – Required for removal of serviceable parts.
Clearance to Combustibles – Required clearance to combustible material.
Minimum Operation Clearance** – Required clearance for proper unit operation.
Installation of the ETL/CSA certified units must conform with local building codes. In the absence of local codes, units must be installed according to the current National Fuel Gas Code ANSI Z223.1/NFPA 54. When installed, the unit must be electrically wired and grounded according to local codes or, in the absence of local codes, with the current National Electric Code, ANSI/NFPA 70 The current American National Standard (ANSIZ233.1/ NFPA54) National Fuel Gas Code is available from the following address: American National Standard Institute Inc. 11 West 42nd Street New York, NY 10036

•  The current National Electric Code (ANSI/NFPA 70) is available from the following address:
  National Fire Protection Association

1 Batterymarch Park
PO Box 9101
Quincy, MA 02269-9101

Use only the type of gas approved for use with this fur-nace. Refer to unit nameplate. Never test for gas leaks with an open flame. Check all connections with a commercially available soap solution made specifically for leak detection.
NOTE – Furnace must be adjusted to obtain a temperature rise (high and low fire) within the range(s) specified on the unit nameplate. Failure to do so may cause erratic limit operation. Canada The unit is CSA International (CSA) certified for combina-tion heating/cooling for outdoor installations and non-res-idential use only at the clearances to combustible materi-als as listed on the unit nameplate. Installation of CSA international certified units must con-form with current standard CSA B149.1, “Natural Gas and Propane Installation Codes” and applicable local codes. Authorities having jurisdiction should be consulted before installation. The unit must be wired and electrically grounded accord-ing to local codes or, in the absence of local codes, cur-rent CSA Standard C22.1 Canadian Electrical Code Part 1. Installation of combination heating/cooling units must also conform with current CSA Standard B52 “Mechanical Refrigeration Code.”

Connect Gas Piping

A manual main shut-off valve must be installed external to the unit when local codes require the installation of such a valve. Install a ground joint union between the gas control mani-fold and the main manual shut-off valve. When making piping connections a drip leg should be in-stalled on vertical pipe runs to serve as a trap for sediment or condensate. A 1/8” N.P.T. plugged tap is located on gas valve for test gauge connection. See Figure 4 through Figure 8 for tap location. See Figure 9 for gas supply piping entry through the side of the unit and Figure 10 for gas piping through the bottom of the unit. A kit is required when routing gas supply piping through the bottom of the unit. Compounds used on threaded joints of gas piping must be resistant to the actions of liquified petroleum gases.

High Alititue Derate

Locate the high altitude conversion sticker in the unit liter-ature bag. Fill out the conversion sticker and affix next to the unit nameplate.
Refer to table 1 for high altitude adjustments.
TABLE 1
HIGH ALTITUDE DERATE

*Units installed at 0-2000 feet do not need to be modified.
NOTE – This is the only permissible derate for these units.

High Altitude Derate – ULNOx Units

Ultra-Low NOx units are approved for installations from 0 -4500 ft. No modifications are required. Above 2000 ft, the furnace will naturally de-rate approximately 10%.

Pressure Test Gas Piping

Operating pressures at the unit gas connection must be as shown in table 2.
TABLE 2
OPERATING PRESSURE AT GAS CONNECTION “w.c

Model

| Natural Gas| LP/ Propane Gas
---|---|---
Min.| Max.| Min| Max.
KG/KD 024-090| 4.5| 10.5| 11| 13
KG/KD 092-300| 4.7| 10.5| 11| 13

When testing the pressure of gas lines, the gas valve must be disconnected and isolated. Gas valves can be dam-aged if subjected to more than 0.5 psig.

WARNING

FIRE OR EXPLOSION HAZARD Failure to follow the safety warnings exactly could result in serious injury, death or property damage. Never test for gas leaks with an open flame. Use a commercially available soap solution made specifically for the detection of leaks to check all connections. A fire or explosion may result causing property damage, personal injury or loss of life.

Two-Stage Gas Valve Adjustment

Gas manifold pressures should match pressures shown in table 3. On two stage gas valves, initiate a W2 thermostat demand to check high fire pressure before low fire pres-sure. With high fire operating, reduce the thermostat de-mand to W1 and check the low fire pressure. Refer to the Unit Controller manual to initiate a thermostat demand.
IMPORTANT – Do not set low fire pressure lower than the certified minimum input rating listed in table 3.
TABLE 3
MANIFOLD INPUT PRESSURES in.wg. (kPa)

Unit

| Natural Gas| Propane (LP)Gas
---|---|---
1st Stg

±0.2

| 2nd Stg

± 0.3.

| 1st Stg

±0.2

| 2nd Stg

± 0.3.

024, 030, 036, 048, 060, 072,

074 Std./Med./High Heat

| NA| 3.5| NA| 10.5
036, 048, 060, 072, 074,

090 Dual Heat

| 2.0| 3.5| 5.9| 10.5
092-300| 1.6| 3.7| 5.5| 10.5

Gas Heat Operation

Non-ULNOx Units
See the operating instruction plate on the unit for details.
ULNOx Units
Use the following steps to correctly measure manifold pressure:

1.  Remove the threaded plug from the outlet side of the gas valve and install a field-provided barbed fitting. Connect measuring device “+” connection to barbed fit-ting to measure manifold pressure. Start unit and allow 5 minutes for unit to reach steady state.
2.  After allowing unit to stabilize for 5 minutes, record manifold pressure and compare to value given in table
3.  Make manifold adjustment if necessary
4.  Shut unit off and remove manometer as soon as an accurate reading has been obtained.

TABLE 4
ULNOx Manifold Pressures (in.w.c.)

Proper Combustion – ULNOx Units
Restart unit and check for any gas leaks. Seal any leaks if found. Furnace should operate minimum 15 minutes with correct manifold pressure and gas flow rate before checking combustion. Table 5 shows acceptable combustion. The maximum carbon monoxide reading should not exceed 100 ppm.
TABLE 5
CO2 RATES (ppm)

ULNOx Operation
ULNOx units are not equipped with gas orifices that sup-ply each burner. Instead, a single gas orifice supplies gas to the air/gas elbow. An intake air orifice supplies combus-tion air to the air/gas elbow. The combustion air blower draws the air/gas mixture from the air/gas elbow into the air/gas plenum box. When the spark ignites the gas, the ignition sensor proves the flame and combustion occurs in the burner premix plate. The burner box liner directs the flames into the burner tube sleeves.

Typical Gas Heat Schematic

Typical Unit Schematic

Proper Gas Flow (Approximate)

1.  Operate unit at least 15 minutes before checking gas flow. Determine the time in seconds for two revolutions of gas through the meter. (Two revolutions assures a more accurate time.) A portable LP gas meter (17Y44) is available for LP applications.
2.  Divide the number of seconds by two and compare to the time in table 6. If manifold pressure is correct and rate is incorrect, check gas orifices for proper size and restriction.
3.  Remove temporary gas meter if installed.
   NOTE – To obtain accurate reading, shut off all other gas appliances connected to meter. Unit Input Rate (Btuh)| Seconds for One Revolution
   ---|---
   Natural| LP
   1 cu ft Dial| 2 cu ft Dial| 1 cu ft Dial| 2 cu ft Dial
   65,000| 55| 111| 138| 277
   78,000| 46| 92| 115| 231
   108,000| 33| 67| 83| 167
   125,000| 29| 58| 72| 144
   130,000| 28| 55| 69| 138
   150,000| 24| 48| 60| 120
   169,000| 21| 43| 53| 107
   180,000| 20| 40| 50| 100
   240,000| 15| 30| 38| 75
   260,000| 14| 28| 35| 69
   360,000| 10| 20| 30| 50
   480,000| 8| 15| 19| 38
   Natural-1000 btu/cu ft| LP-2500 btu/cu ft|

NOTE – Table assumes standard temperature (60°F), pressure (30in.Hg.), and fuel heating values (Btuh/Ft.3). Apply pressure corrections in alti-tudes above 2000 ft.

Repair Parts Listing

When ordering repair parts, include the complete model number and serial number listed on the ETL/CSA rating plate –

• e.g. LGH120S4BH1Y.
• Gas Heat Section Parts
• Heat Exchanger
• Combustion Air Assembly Combustion Air Proving Switch Burner Assembly
• Burner Manifold Assembly Main Burner Orifices
• Flame Roll-out Switches Auxiliary Limit Controls Ignition Electrode Assembly Ignition Lead
• Ignition Sensor Assembly Sensor Lead
• Combination Gas Valve
• Limit Controls
• Additional for ULNOx Units: Intake Air Screen
• Intake Air Orifice
• Air/Gas Elbow
• Air/Gas Plenum Box
• Burner Premix Plate
• Burner Box Liner & Tubes Inlet Reducer
• Rubber Coupling
• Cooling Parts
• Compressors
• Condenser Fan Motors Condenser Fan Blades Condenser Fan Run Capacitors Freezestats
• Condenser Fan Mounting Bracket Fan Grille
• Indoor Blower Motors
• Blower Wheel
• Expansion Valve
• Distributor
• Exhaust Fans (Opt.)
• Reversing Valve (KD only)
• Electrical Control Parts
• Compressor Contactors Circuit Breakers (Opt.) Transformer (Control) Transformer (Contactor) Blower Contactor
• Limit, Blower Relay
• Heat Relays
• Condenser Fan Relays Capacitor CAB
• Relay CAB
• Disconnect Switch (Opt.) Defrost Control (KD only) Fan Control Board (KD only)

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