REZNOR UBXC 30 Gas Fired Unit Heaters Instruction Manual

: August 20, 2024
: Reznor

Table of Contents

REZNOR UBXC 30 Gas Fired Unit Heaters
Product Usage Instructions
CONVERSION KIT INSTALLATION
References
Read User Manual Online (PDF format)
Download This Manual (PDF format)

REZNOR UBXC 30 Gas Fired Unit Heaters

REZNOR-UBXC-30-Gas-Fired-Unit-Heaters-PRODUCT

Specifications

Model: UBXC and UDXC
Conversion Type: Separated-Combustion
Compatibility: Gas-Fired Unit Heaters
Options: SC1 for Models UBXC and UDXC

Product Usage Instructions

Conversion Kit Components
Before starting the installation, make sure you have all the components listed in Table 1.

Conversion Kit Installation

Ensure that gas and electric supply to the heater are OFF.
Seal any unused suspension point holes in the top of the heater using capscrews and sealing washers from the kit.
Remove the access door panel and install the gasket as shown in Figure 1.
Install the door safe switch following the steps provided in Figure 2.
Install the combustion air inlet collar and gasket on the combustion air opening and secure using screws.
Install the gas supply line grommet on the gas connection on the back of the heater.

Frequently Asked Questions (FAQ)
Q: Do I need special tools to perform the conversion?
A: It is recommended to use standard tools like screwdrivers, wrenches, and pliers for the installation process. No special tools are required.

SE PARATED-COMBUSTION CONVERSION OF GAS-FIREDUNIT HEATERS
OPTION SC1 FOR MODELS UBXC AND UDXC

NOTE: Conversion should be done by a qualified agency in accordance with these instructions and in compliance with all codes and requirements of authorities having jurisdiction.

These instructions are for converting a standard UBXC or UDXC model to a separated-combustion unit.
Refer to the installation manual provided with the heater for important safety information.

CONVERSION KIT COMPONENTS
NOTE: Separated-combustion conversion requires either the vertical (option CC2) or horizontal (option CC6) vent/combustion air inlet terminal kit.
Ensure that all components listed in Table 1 are available before beginning installation.

Table 1. Conversion Kit Components

Component

|

Description

| Model and Unit Size (MBTUh)
UBXC 30, 60, 75,

100, 125

| UBXC 150, 175, 200,

225, 250, 300, 350, 400

|

UBXC 45

UDXC 30, 45, 60,

75, 100, 125

| UDXC 150, 175, 200,

225, 250, 300, 350, 400

DANGER
Ensure that the gas and electric supply to the heater are OFF before beginning conversion kit installation.
DO NOT DESTROY. PLEASE READ CAREFULLY. KEEP IN A SAFE PLACE FOR FUTURE REFERENCE.

CONVERSION KIT INSTALLATION

Ensure that gas and electric supply to heater are OFF.
Seal any unused suspension point holes in top of heater using capscrews and sealing washers from kit. If heater has already been installed and adequate clearance does not exist to plug these holes, heater will need to be removed from its suspension location.
Remove access door panel and install gasket (see Figure 1):
- Remove four rubber door bumpers.
- Cut to size four pieces of D-shaped seal gasket. Discard excess gasket material.
- Peel backing and adhere gasket to inside flange of access door panel.
  $REZNOR-UBXC-30-Gas-Fired-Unit-Heaters- $2$$
Install door safe switch:
- Snap in switch in cutout on right side of access door panel opening.
- Remove connector from terminal R on terminal strip on back of heater.
- Connect one end of red door safe switch wire from kit to terminal R on terminal strip (see Figure 2).
- Connect other end of red wire to open terminal on switch.
  $REZNOR-UBXC-30-Gas-Fired-Unit-Heaters- $3$$
Install combustion air inlet collar and gasket (see Figure 2) on combustion air opening and secure using screws.
Install gas supply line grommet on gas connection on back of heater. If heater has already been installed, TURN OFF GAS SUPPLY, disconnect gas supply connection, install grommet, and reconnect gas supply.
If heater has not been installed, complete heater installation in accordance with installation manual provided with heater.
Install venting system in accordance with VENT CONNECTIONS FOR SEPARATED-COMBUSTION UNITS section.
Turn ON gas and electric supply.
Light heater in accordance with lighting instructions and check for proper operation.

VENT CONNECTIONS FOR SEPARATED-COMBUSTION UNITS

DANGER
Do not enclose the vent pipe or place it closer than 6 inches (152 mm) to combustible material.

WARNING
All separated combustion units MUST BE equipped with both combustion air and exhaust piping to the outdoors.

CAUTION
Concentric horizontal and vertical vent/combustion air systems are the only venting/combustion air systems approved for these units.
The vertical vent terminal pipe does not connect to the concentric adapter box and must be supported during installation.
NOTE: Refer to the General Requirements for Vent Connections section in the installation manual provided with the heater.

Pipe Requirements

All pipe is field-supplied. Select the installation type that applies. Requirements are listed for both the vent pipe and the combustion air inlet pipe:

Pipe Requirements for Residential Installations

Single-wall vent pipe approved to UL standard 1738 for a category III appliance is required.
The horizontal section of pipe in the vent terminal that extends through the box and runs concentric through the combustion air pipe must be one-piece with no joints.
The vertical section of pipe in the vent terminal that extends through the box and runs concentrically through the combustion air pipe must be one piece with no joints.
Sealed, single-wall galvanized pipe is recommended for the inlet air run and the terminal combustion air pipe.

Pipe Requirements for Commercial/Industrial Installations

Single-wall vent pipe approved for a category III appliance or single-wall, 26-gauge or heavier galvanized or equivalent vent pipe is required between the heater and the concentric adapter box.
The horizontal section of pipe in the vent terminal that extends through the box and runs concentric through the combustion air pipe must be one-piece with no joints.
The vertical section of pipe in the vent terminal that extends through the box and runs concentric through the combustion air pipe must be one-piece with no joints. Double-wall (type B) vent pipe is required for the vertical vent terminal.
Sealed, single-wall galvanized pipe is recommended for the inlet air run and terminal combustion air pipe.

VENT CONNECTIONS FOR SEPARATED-COMBUSTION UNITS—CONTINUED
Pipe Size
Pipe diameters of the outside (terminal) concentric pipes are listed in Table 2. Pipe diameter and length requirements listed in Table 3 are for the indoor sections of pipe between the heater and the concentric adapter box.

Table 2. Concentric (Outdoor) Pipe Sizes

Pipe| Unit Size (MBTUh)
30–125| 150–400
Pipe Diameter (Inches (mm))
Inlet air| 6 (152)| 8 (203)
Vent| 4 (102)| 5 (127)
Table 3. Diameter and Length of Pipe (Indoor) from Heater to Concentric Adapter Box

1 (0.3)

4 (102)| 10 (3)
60| 3 (76)| 25 (7.6)| 3 (0.9)| 1.5 (0.5)
4 (102)| 15 (4.6)| 1.5 (0.5)| 1 (0.3)
75| 4 (102)| 25 (7.6)| 3 (0.9)| 1.5 (0.5)
100, 125| 4 (102)| 35 (10.7)| 4 (1.2)| 2 (0.6)
150| 5 (127)| 6 (152)| 30 (9.1)| 3 (0.9)| 1.5 (0.5)|

3 (0.9)

175| 5 (127)| 6 (152)| 30 (9.1)| 3 (0.9)| 2 (0.6)
200, 225, 250| 5 (127)| 6 (152)| 40 (12.2)| 4 (1.2)| 2 (0.6)
300| 6 (152)| 45 (13.7)| 4 (1.2)| 2 (0.6)
350, 400| 6 (152)| 45 (13.7)| 5 (1.5)| 2.5 (0.8)
***** Add all straight sections and equivalent lengths for elbows—the total combined length must not exceed the maximum vent length.

Combustion Air Inlet and Venter Outlet Connection Requirements

Combustion air inlet connection on unit sizes 30, 45, and 60: when using 3-inch diameter pipe, a 3- to 4-inch (76- to 102-mm) taper-type increaser is required at the inlet air collar.
Venter outlet connection on unit sizes 30, 45, and 60: when using 3-inch diameter pipe, a 4- to 3-inch (102- to 76- mm) taper-type reducer is required at the venter outlet—for category III, attach a 4-inch appliance adapter from a category III pipe manufacturer directly to the collar and then use a reducer if using 3-inch pipe.
Both heater connections on unit sizes 200, 225, 250, 300, 350, and 400: require a minimum of 12 inches (305 mm) of straight pipe at both heater connections.

Table 4. Combustion Air Inlet and Venter Outlet Connection Sizes

Connection

| Unit Size (MBTUh)
30–125| 150–250| 300–400
Connection Diameter (Inches (mm))
Venter outlet| 4 (102)| 5 (127)| 6 (152)
Combustion air inlet collar| 6 (152)

NOTES:

All separated-combustion units require a concentric adapter box designed to allow both combustion air and venting. The unique concentric adapter assembly required with this heater allows for both combustion air and exhaust piping with only one horizontal or vertical penetration hole in the building.
The concentric adapter box is included in the vent/combustion air terminal kit. Components and instructions depend on whether the vent terminal is horizontal (option CC6) or vertical (option CC2).
Horizontal and vertical kits do not use the same adapter box. The only difference is the diameter of the opening in the box for the vent pipe. On commercial/industrial installations, a vertical vent requires double-wall pipe and a slightly larger opening through the box.
Figure 3 shows a typical concentric adapter box and its airflow.

$REZNOR-UBXC-30-Gas-Fired-Unit-Heaters- $4$$

VENT CONNECTIONS FOR SEPARATED-COMBUSTION UNITS—CONTINUED $REZNOR- UBXC-30-Gas-Fired-Unit-Heaters- $5$$

Table 5. Vent Pipe Opening Diameter

$REZNOR-UBXC-30-Gas-Fired-Unit-Heaters- $6$$

Table 6 lists connection dimensions shown in Figure 5, DETAIL B.
Unit sizes 300, 350, and 400 shown in Figure 5, DETAIL C always require a 6–5 inch (152–127 mm) taper-type reducer in the vent pipe.

Table 6. Concentric Adapter Box Vent Pipe Sizes

Unit Size (MBTUh)

| Dimension *
A| B| C| D
Diameter (Inches (mm))
30, 45, 60 **| 4 (102)| 6 (152)| 4 (102)
75, 100, 125| 4 (102)| 6 (152)| 4 (102)
150, 175, 200, 225, 250| 5 (127)| 8 (203)| 6 (152)
* See Figure 5.
** Uses 4-inch vent pipe for combustion air runs from heater to concentric adapter box.

Vent Terminal Connections
Vent terminal options CC2 (vertical vent configuration) and CC6 (horizontal vent configuration) are shown in Figure 6. Both options are applicable to residential and commercial/industrial installations

$REZNOR-UBXC-30-Gas-Fired-Unit-Heaters- $7$$

Vertical Vent Terminal (Option CC2) Installation

Field-supplied components required for installation of the vertical vent kit are as follows:
- Vent and combustion air piping in accordance with Table 3.
- Tapered vent pipe diameter reducers and/or increasers, as required.
- Thimble (not required if wall is of non-combustible construction).
- Flashing.
- Sheet metal screws, tape, and sealant, as required.
Factory-supplied components for installation of the vertical vent kit are listed in Table 7.

Table 7. Vertical Vent Terminal/Combustion Air Package (Option CC2) Components

Unit Size (MBTUh)|

Description

|

Qty

30–125| 150–400
PN
205895| 205896| Kit package| 1
205884| 205885| Concentric adapter box (see Figure 3, Figure 4 , and Figure 5)| 1
110051| 110052| Exhaust vent terminal assembly (see Figure 7)| 1
155635| 53330| Combustion air inlet assembly (see Figure 7)| 1
207232| Concentric adapter box bracket| 2
53335| High-temperature silicone sealant, tube| 1

$REZNOR-UBXC-30-Gas-Fired-Unit-Heaters- $8$$

DANGER
To prevent combustion products from entering the occupied space, all vent terminals must be positioned or located away from fresh air intakes, doors, and windows. Failure to comply could result in severe personal injury or death and/or property damage.
Consider local snow depth conditions. The vent must be at least 6 inches (152 mm) above the anticipated snow depth.

Determine vent terminal location on roof:
If more than one vertical vent terminal is being installed, minimum spacing between vent center lines is determined by minimum outdoor design temperature (coldest outdoor condition at installation site). Refer to Table 8 to ensure that location complies with minimum outdoor design temperature requirements.
Select location away from fresh air intakes, allowing space for concentric adapter box inside. Vent terminal must be located away from adjacent buildings as shown in Figure 8.

Table 8. Minimum Spacing Between Center Lines of Vertical Vent Pipes

Minimum Outdoor Design Temperature| Minimum Spacing Between Center Lines of Vertical Vent Pipes (Inches (mm))
³31°F (³0°C)| 36 (914)
−10 to 30°F (−23 to −1°C)| 60 (1524)
< −10°F (< −23°C)| 84 (2134)

VENT CONNECTIONS FOR SEPARATED-COMBUSTION UNITS—CONTINUED $REZNOR-UBXC-30-Gas-Fired-Unit-Heaters- $9$$
Install vent pipe and combustion air pipe runs:
Connect piping to heater in accordance with specifications listed in Pipe Requirements section.
Seal all joints in accordance with specifications listed in Vent System Sealing section of installation manual provided with heater. Due to high temperature considerations, do not enclose exhaust pipe or place pipe closer than 6 inches (152 mm) to combustible material.
Extend piping runs close to roof at location selected in step 1 and support piping in accordance with specifications listed in Vent System Support Requirements section of installation manual provided with heater.
NOTE: The vent pipe will extend through the roof after the concentric adapter box is installed. The indoor combustion air pipe will end at the box.
Cut hole through roof for combustion air pipe.
Ensure that location and orientation of concentric adapter box are correct and mark and cut hole.
Ensure that hole accommodates 6-inch (152 mm) combustion air pipe for unit sizes 30–125 or 8-inch (203-mm) combustion air pipe for unit sizes 150–400. Thimble may or may not be required depending on building construction and/or local codes. Larger diameter combustion air pipe serves as clearance for vent pipe on non-combustible construction.
Secure longer angles on concentric adapter box brackets (see Figure 9) to concentric adapter box.
NOTE: The longer angle of the concentric adapter box bracket has five 7/32-inch holes that allow the position of the bracket on the box to be adjusted. The shorter angle has three 7/32-inch holes that allow adjustment to construction.
Connect outside section of combustion air pipe to concentric adapter box (see Figure 10):
Determine length of combustion air pipe so that dimension X in Figure 10 is equal to bracket length, plus roof thickness, plus anticipated snow depth. Ensure that length of combustion air pipe does not exceed 48 inches (1,219 mm) or does not extend less than 18 inches (457 mm) above roof.
Secure inlet air pipe to collar of concentric adapter box using sheet metal screws. Seal joint and seam using tape or sealant. $REZNOR-UBXC-30-Gas-Fired-Unit-Heaters- $11$$
Secure concentric adapter box to underside of roof (see Figure 10):

CAUTION

If the roof is combustible, ensure that brackets are positioned to allow a 2-inch (51 mm) clearance between the concentric adapter box and the roof.
If any holes are made in the concentric adapter box in error, ensure that they are sealed.
Insert combustion air pipe through roof as shown in Figure 11.
Position concentric adapter box to match pipe runs and secure short angles of concentric adapter brackets (see Figure 9) to underside of roof using field-supplied hardware.
Install field-supplied flashing around combustion air pipe on roof outside.
Install double-wall terminal vent pipe
NOTE: The length of the vent pipe is determined by the installation within maximum and minimum requirements. The vent pipe extending through the concentric adapter box, through the combustion air inlet pipe, and above the combustion air inlet air pipe must be one piece without joints.
Refer to Figure 10 to determine required length of continuous section of vent pipe. Determine length as follows:
Start with no more than 6 inches (152 mm) below concentric adapter box
Plus 6 inches (152 mm) through box
Plus length of bracket extending above box
Plus width of roof
Plus height of combustion air pipe above roof
Plus minimum of 3 inches (76 mm) beyond top of combustion air pipe
Total is minimum length of vent pipe section—if actual piece of vent pipe is longer, extend it further above combustion air pipe—do not extend it more than 6 inches (152 mm) below box
Ensure that vent pipe is in proper flow direction and slide end of pipe into box and out through combustion air pipe. Position vent pipe to lengths determined above.
NOTE: The double-wall vent pipe does not attach to the box. The installer must provide support.
Connect double-wall pipe to single-wall pipe or taper-type connector in accordance with Vent System Sealing section of installation manual provided with heater.
Seal completely around circumference of pipe and opening of box using silicone sealant.
Install combustion air inlet (see Figure 12):
Install additional section of vent pipe if needed on outside and make joint in accordance with pipe manufacturer’s requirements.
When vent pipe is required height, slide combustion air inlet over vent pipe and fasten collar to combustion air pipe using sheet metal screws.
Seal opening at top between vent pipe and combustion air inlet to prevent water leakage using silicone sealant. $REZNOR-UBXC-30-Gas-Fired-Unit-Heaters- $13$$
Install exhaust (vent) terminal cap (see Figure 12) in accordance with Vent System Sealing section of installation manual provided with heater.
Install indoor combustion air pipe:
Secure single-wall combustion air pipe run to collar on concentric adapter box using field-supplied sheet metal screws.
Seal pipe joint using tape or sealant.
Verify compliance with Figure 8 and with all specifications and requirements listed in this manual.
Horizontal Vent Terminal (Option CC6) Installation
Field-supplied components required for installation of the horizontal vent kit are as follows:
Vent and combustion air piping in accordance with Table 3.
Tapered vent pipe diameter reducers and/or increasers, as required.
Thimble (not required if wall is of non-combustible construction).
Flashing.
Sheet metal screws, tape, and sealant, as required.
Factory-supplied components for installation of the horizontal vent kit are listed in Table 9.

Table 9. Horizontal Vent Terminal/Combustion Air Package (Option CC6) Components

Unit Size (MBTUh)| ****

Description

| ****

Qty

30–125| 150–400
PN
211762| 211763| Kit package| 1
211789| 211790| Concentric adapter box (see Figure 3, Figure 4 , and Figure 5)| 1
211791| 211792| Exhaust grill (see Figure 13)| 1
151755| 124940| Inlet guard (see Figure 13)| 1
207232| Concentric adapter box bracket| 2
37661| Screw, sheet metal, #10-16 × 1/2| 8
53335| High-temperature silicone sealant, tube| 1

$REZNOR-UBXC-30-Gas-Fired-Unit-Heaters- $14$$

DANGER

To prevent combustion products from entering the occupied space, all vent terminals must be positioned or located away from fresh air intakes, doors, and windows. Failure to comply could result in severe personal injury or death and/or property damage.
In climates with below freezing temperatures, condensate may form icicles on the vent terminal. Locate the terminal where falling icicles do not present a hazard.
Consider local snow depth conditions. The vent must be at least 6 inches (152 mm) above the anticipated snow depth.

Determine vent/combustion air terminal location on outside wall:
- Refer to Table 3 to ensure that location complies with vent length requirements
- For most applications, ensure that vent terminal is level with heater mounting height.
- Allow downward pitch of 1/4-inch per foot (6 mm per 305 mm) for condensate drain.
- Ensure that distance of vent terminal from adjacent public walkways and buildings and window and building openings complies with local codes. Absent any local codes, distance must comply with National Fuel Gas Code (ANSI Z223.1).
  WARNING
  Avoid positioning the vent terminal above a walkway as there may be a small amount of condensate that drips from the end of the vent/combustion air terminal. In cold climates, the condensate may form ice.
- CAUTION
- Products of combustion can cause discoloration of some building finishes and deterioration of masonry materials. A clear silicone sealant normally used to protect concrete driveways may be used to protect masonry materials from discoloration and deterioration. If discoloration is an esthetic problem relocate the vent or install a vertical vent.
- Refer to Vent Terminal Requirement section of installation manual provided with heater to ensure that location complies with minimum clearance requirements.
Install vent pipe and combustion air pipe runs:
- Connect piping to heater in accordance with specifications listed in Pipe Requirements section.
- Seal all joints in accordance with specifications listed in Vent System Sealing section of installation manual provided with heater. Due to high temperature considerations, do not enclose exhaust pipe or place pipe closer than 6 inches (152 mm) to combustible material.
- Extend piping runs close to roof at location selected in step 1 and support piping in accordance with specifications listed in Vent System Support Requirements section of installation manual provided with heater.
Cut hole through outside wall for combustion air pipe.
- Ensure that outside wall construction thickness is between 1 inch (25 mm) minimum and 48 inches (1,219 mm) maximum.
- Ensure that hole accommodates 6-inch (152 mm) combustion air pipe for unit sizes 30–125 or 8-inch (203-mm) combustion air pipe for unit sizes 150–400. Thimble may or may not be required depending on building construction and/or local codes. Larger diameter combustion air pipe serves as clearance for vent pipe on non-combustible construction.
Secure longer angles on concentric adapter box brackets (see Figure 9) to concentric adapter box.
NOTE: The longer angle of the concentric adapter box bracket has five 7/32-inch holes that allow the position of the bracket on the box to be adjusted. The shorter angle has three 7/32-inch holes that allow adjustment to construction.
Connect outside section of combustion air pipe to concentric adapter box (see Figure 14):
Determine length of combustion air pipe as follows:
Bracket length from box to wall
Plus wall thickness
Plus 4–16 inches (102–406 mm) beyond wall
Secure inlet air pipe to collar of concentric adapter box using sheet metal screws. Seal joint and seam using tape or sealant.
Secure concentric adapter box to wall (see Figure 14):
CAUTION
If the wall is combustible, ensure that brackets are positioned to allow a 2-inch (51 mm) clearance between the concentric adapter box and the wall.
- If any holes are made in the concentric adapter box in error, ensure that they are sealed.
- Insert combustion air pipe out through wall.
- Secure short angles of concentric adapter box brackets (see Figure 9) to wall.
- Seal or flash inlet air pipe on outside using sealant and/or field-supplied flashing.
Install inlet guard:
- Position inlet guard over end of combustion air pipe in accordance with Figure 14.
- Secure inlet guard to inlet air pipe using four 1/2-inch-long screws provided.

VENT CONNECTIONS FOR SEPARATED-COMBUSTION UNITS—CONTINUED $REZNOR-UBXC-30 -Gas-Fired-Unit-Heaters- $15$$

Install terminal-end vent pipe:
NOTE: The length of the terminal-end vent pipe is determined by the installation within maximum and minimum requirements. The vent pipe extending through the concentric adapter box, through the combustion air inlet pipe, and above the combustion air inlet air pipe must be one piece without joints. The connection to the vent pipe run must be a maximum of 6 inches (152 mm) from the heater side of the box.
Refer to Table 10 to determine lengths of each pipe segment and to calculate total length required.
Ensure that terminal-end vent pipe is in proper flow direction and slide end of pipe through box.
Position vent pipe so that it extends 3–6 inches (76–152 mm) past end of combustion air pipe and no more than 6 inches (152 mm) out of box toward heater.
Connect terminal-end vent pipe to vent pipe run no more than 6 inches (152 mm) from heater.

Table 10. Horizontal Vent Dimensions

Unit Size (MBTUh)| Dimension (See Figure 14 )
X (Feet (Meters)) ***| Y (Inches (mm))**
30, 45|

4 (1)

| 9 (229)
60, 75, 100| 12 (305)
125–225| 24 (610)
250–400| 6 (2)| 36 (914)
***** Minimum—check and comply with local codes.

Install exhaust grill

Position exhaust grill over end of vent pipe in accordance with Figure 14.
Secure exhaust grill to end of vent pipe using four 1/2-inch-long screws provided.
Seal vent pipe to concentric adapter box.
Ensure that terminal-end section of vent pipe has slight downward pitch of 1/4-inch (6-mm) per foot (305 mm) toward outside.
Seal completely around circumference of pipe and opening of box using silicone sealant.Install indoor section of combustion air pipe:
Secure single-wall combustion air pipe run to collar on concentric adapter box using sheet metal screws.
Seal pipe joint using tape or sealant.
Verify compliance with Figure 14 and with all specifications and requirements listed in this manual.

ADJUSTMENTS
After startup, the combination gas valve outlet pressure must be measured and adjusted if necessary in accordance with the Measure and Adjust Manifold (Outlet) Gas Pressure section in the installation manual provided with the heater. If the heater is being installed at an elevation of >6,000 feet (>1,830 meters), the pressure switch must be replaced in accordance with the Pressure Switch Replacement section in the installation manual provided with the heater before the gas pressure is adjusted. Ensure that the pressure switch is adjusted in acordance with Table 11.

NOTE: When converting a unit size 45 of model UBXC, replace the pressure switch (refer to Table 1) in accordance with the Pressure Switch Replacement section in the installation, operation, and maintenance manual provided with unit.

Table 11. Pressure Switch Settings for Separated-Combustion Units

Unit Size (MBTUh)

| Model
UBXC| UDXC
Startup Cold| Equilibrium Hot| Setpoint OFF| Setpoint ON| Startup Cold| Equilibrium Hot| Setpoint OFF| Setpoint ON
Differential Pressure (IN WC)
30| 1.20| 0.90| 0.50| 0.70| 1.20| 0.90| 0.65| 0.80
45| 1.00| 0.80| 0.50| 0.70| 1.00| 0.80| 0.50| 0.65
60| 0.90| 0.80| 0.60| 0.80| 0.90| 0.80| 0.40| 0.55
75| 0.80| 0.70| 0.50| 0.70| 0.80| 0.70| 0.45| 0.60
100| 0.90| 0.70| 0.45| 0.65| 0.90| 0.70| 0.50| 0.65
125| 1.40| 1.00| 0.60| 0.80| 1.40| 1.00| 0.80| 0.95
150| 0.70| 0.60| 0.40| 0.60| 0.70| 0.60| 0.35| 0.50
175| 2.30| 1.40| 1.10| 1.30| 0.80| 0.70| 0.40| 0.55
200, 225| 2.30| 1.60| 1.10| 1.30| 2.30| 1.60| 1.10| 1.30
250| 2.70| 1.80| 1.30| 1.50| 2.70| 1.80| 1.10| 1.30
300| 2.50| 1.90| 1.30| 1.50| 2.50| 1.90| 1.10| 1.30
350, 400| 2.10| 1.60| 1.30| 1.50| 2.10| 1.60| 1.30| 1.50

DOOR SAFE SWITCH MAINTENANCE
The door safe switch prevents the heater from operating when the access door panel is open. If it is determined that the interlock door switch needs replacing, use only a factory-authorized replacement part that is designed for the heater.

CAUTION
Verify that the door safe switch operates when opening the access door panel. While a temporary bypass of the switch may be required for troubleshooting, always return the switch to normal operation once troubleshooting is complete. Do not permanently bypass the switch.

Specifications and illustrations subject to change without notice or incurring obligations. Latest version of this manual is available at www.reznorhvac.com
©2024 Nortek Global HVAC LLC, O’Fallon, MO. All rights reserved.
UBXC-UDXC-SC1 (02-24) 1042982-0