Reznor UDX Installation, Operation And Maintenance Manual

Reznor UDX Installation, Operation And Maintenance Manual

Gas-fired unit heater
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GAS-FIRED UNIT HEATER INSTALLATION, OPERATION,
AND MAINTENANCE
• Failure to follow safety warnings exactly could result in serious injury, death, or property
damage.
• Improper installation, adjustment, alteration, service, or maintenance can cause serious injury,
death, or property damage.
• Installation and service must be performed by a qualified installer, service agency, or the
gas supplier.
• Be sure to read and understand the installation, operation, and service instructions in this
manual.
• Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or
any other appliance.
• Do not try to light any appliance.
• Do not touch any electrical switch; do not use any phone in your building.
• Leave the building immediately.
• Immediately call your gas supplier from a phone remote from the building. Follow the gas
supplier's instructions.
• If you cannot reach your gas supplier, call the fire department.
DO NOT DESTROY. PLEASE READ CAREFULLY. KEEP IN A SAFE PLACE FOR FUTURE REFERENCE.
Revision: UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K
Supersedes: UBX-UBZ-UDX-UDZ-IOM (02-23) 1034344-J
MODELS UBX, UBZ, UDX, AND UDZ
 ⚠ DANGER ⚠ 
FIRE OR EXPLOSION HAZARD
WHAT TO DO IF YOU SMELL GAS

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Do you have a question about the UDX and is the answer not in the manual?

Questions and answers

Aaron G Lange
May 7, 2025

does a udx 150 require a combustion air vent when installed in a commercial wood shop

1 comments:
Mr. Anderson
May 19, 2025

Yes, the Reznor UDX 150 requires sufficient combustion air for installation. It must be supplied with air that enters the combustion process and is then vented outdoors. Enough air must be provided to ensure there is no negative pressure in the equipment room. If the commercial wood shop is tightly sealed, outside air may need to be introduced through wall openings or ducts.

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Summary of Contents for Reznor UDX

  • Page 1 Revision: UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K Supersedes: UBX-UBZ-UDX-UDZ-IOM (02-23) 1034344-J GAS-FIRED UNIT HEATER INSTALLATION, OPERATION, AND MAINTENANCE MODELS UBX, UBZ, UDX, AND UDZ  ⚠ DANGER ⚠  FIRE OR EXPLOSION HAZARD • Failure to follow safety warnings exactly could result in serious injury, death, or property damage.
  • Page 2: Table Of Contents

    Measure and Adjust Manifold Gas Pressure—Elevation >2,000 Feet (>610 Meters) . . . . . . . . . . . . . . . . . . 31 UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 3: General Information

    Flame Rollout Switch Maintenance (Models UDX and UDZ Unit Sizes 030–125 Only) . . . . . . . . . . . . . . .
  • Page 4: Important Safety Information

    • A fan model is connected to a duct system or if the air delivery system is modified . Model Configuration Table 2. Model Configuration Model Configuration Model Configuration Standard power-vent blower-type Separated-combustion blower-type Standard power-vent fan-type Separated-combustion fan-type UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 5: Certification

    • These unit heaters are listed by Intertek for use in industrial and commercial installations in the United States and Canada . In addition, models UDX and UDZ in unit sizes 030, 045, 060, 075, 100, and 125 are listed in the United States and Canada as utility heaters for use in non-living spaces that are attached to, adjacent to, or part of a structure that contains space for family living quarters .
  • Page 6: Heater Throw

    53 (16 .2) Downward louver angle 54° 58° 50° 51° 11 (3 .4) 11 (3 .4) 17 (5 .2) 17 (5 .2) 18 (5 .5) — 40 (12 .2) 44 (13 .4) Downward louver angle 57° 58° Figure UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 7: Mounting Height Requirements

    300 grade stainless steel . Care should be taken to separate these vapors from the combustion process . This may be done by wise location of the unit with regard to exhausters or prevailing wind directions . UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 8: Dimensions

    GENERAL INFORMATION—CONTINUED Dimensions NOTE: Power-vent models UBX and UDX have a combustion air inlet grill and ARE NOT to be connected to a combustion air inlet pipe. TOP VIEW DIRECT-DRIVE BLOWER (UNIT SIZES 100–125) HANGER 2-1/2 FRONT VIEW SIDE VIEW (DIRECT-DRIVE BLOWER, UNIT SIZES 030–075)
  • Page 9 Varies with motor selection and belt adjustment for unit sizes 150–400 . Heater suspension points (3/8-16 FEM) . COMBUSTION AIR INLET THERMOSTAT CONNECTION VENT CONNECTION CONNECTION TOP VIEW REAR VIEW FRONT VIEW SIDE VIEW Figure 3. Dimensions—Models UDX and UDZ (Refer to Table UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 10: Clearances

    GENERAL INFORMATION—CONTINUED Dimensions—Continued Table 5. Dimensions—Models UDX and UDZ Unit Size Dimension 030, 045 150, 175, 200 225, 250 300, 350, 400 (See Figure Inches (mm) 13-3/4 (349) 16-3/4 (425) 24-3/4 (629) 20-1/8 (511) 26-1/8 (664) 34-1/8 (867) 27 (686)
  • Page 11: Weights

    • For UBZ and UDZ models, refer to the combustion air requirements in the venting instructions listed in • UBX and UDX models must be supplied with the air that enters into the combustion process and is then vented to the outdoors . Sufficient air must enter the equipment location to replace that which is exhausted through the heater vent system .
  • Page 12: Installation

    ‰ If you do not have knowledge of local requirements, check with the local gas company or any other local agencies who might have requirements concerning this installation . ‰ Before beginning, make preparations for necessary supplies, tools, and manpower . UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 13: Heater Suspension

    • Before suspending the heater, check the supporting structure to be used to verify that it has sufficient load-carrying capacity to support the weight (refer to Weights section) of the unit. • The heater must be level for proper operation. DO NOT place or add additional weight to a suspended heater. UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 14: Suspension Of Heater Using Option Ck8 Or Ck10 Hanger Kit

    3/8-inch threaded rods or a hanger kit option package . • On heater models UBX and UDX, shipped-separate option packages—that should be installed before the heater is suspended—include vertical louvers, high-elevation kit, multiple heater control, sensor for DDC control, and/ or stepdown transformer .
  • Page 15: Suspension Of Heater Using Option Ck22 Hanger Kit

    The ceiling suspension kit (option CK22) allows the heater to be installed 1 inch from the ceiling without hanger rods . The ceiling suspension kit is used only on unit sizes 030–125 for UDX and UDZ models . Refer to the installation instructions provided with the kit .
  • Page 16: Gas Supply Piping

    • The National Fuel Gas Code requires the installation of a trap with a minimum 3-inch drip leg (see codes may require a drip leg longer than 3 inches (typically 6 inches) . To permit burner removal, this drip leg must extend beyond the edge of the heater . UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 17: Electrical Connections

    . • All external wiring must be within approved conduit and have a minimum temperature rise rating of 60°C . Conduit must be run so as not to interfere with the heater access panel . UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 18 • UDZ and UBZ units have a built-in disconnect switch (20A@115V or 10A@230V rating) . Figure 9 . For UBX and UDX models, the supply • The supply wiring enters at the rear of the heater, as shown in wiring connects directly to leads on the integrated circuit board . For UBZ and UDZ models, the supply wiring connects to the disconnect toggle switch .
  • Page 19: Controls

    . • On UBX and UDX models, the pressure switch is a single-pole/normally-open device that closes when a negative pressure is sensed in the venter housing . On UDZ and UDZ models, the pressure switch senses the differential pressure between the negative pressure in the venter housing and the pressure in the cabinet .
  • Page 20 . The main burner will remain off until the system has cooled and/or the flue system resistance is reduced . Table 12 . • Pressure switch settings are listed in Table 12. Pressure Switch Settings UBX and UDX Models Negative Pressure (IN WC) Unit Size Label Color Startup Cold Equilibrium Hot...
  • Page 21: High Temperature Limit Control

    If the manual-reset flame rollout switch activates, identify and correct the cause before resetting the switch. Never bypass the flame rollout switch; hazardous conditions could result. Unit sizes 030–125 of UDX and UDZ models are equipped with a temperature-activated, manually-reset flame rollout Figure 11 switch (see for location) .
  • Page 22: Thermostat Options

    . The module’s Seven-Segment Display (SSD) is visible through a viewport on UBZ and UDZ models . To view the SSD on UBX and UDX models, the door panel requires removal . In addition, there is a status LED on the bottom of the heater .
  • Page 23: Operation

    1 . Set thermostat at lowest setting . 2 . Turn OFF all electric power to appliance . NOTE: This appliance is equipped with an ignition device that automatically lights the burner. Do not try to light the burner by hand. UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 24 . If service is to be performed, turn off all electric power to appliance . c . Open the access door . d . Turn gas control switch to OFF or turn knob clockwise to OFF (do not force) . e . Close access door . UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 25: Operating Sequences

    Control deenergizes gas valve and proceeds to steps 6 and 7 removed 6 . Post-purge Venter motor remains on for 45-second post-purge period Thermostat is satisfied 7 . Fan/blower Fan/blower motor is deenergized after selected fan/blower OFF delay OFF delay UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 26 Fan remains energized as long as call for fan remains without call for heat Fan/blower is deenergized Thermostat calls for heat (W) during continuous fan operation Call for fan is ignored during lockout The limit switch is ignored unless a call for heat is present (terminal W energized) . UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 27: Vent System Testing

    8 . After it has been determined that each heater connected to vent system properly vents when tested as outlined above, return doors, windows, exhaust fans, fireplace dampers, and any other gas-burning appliance to their previous condition of use . 9 . If improper venting is observed during above tests, vent system must be corrected . UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 28: Post-Startup Checklist

    NEVER RESTRICT OR OTHERWISE ALTER THE SUPPLY OF COMBUSTION AIR TO ANY HEATER. Heater models UBX and UDX installed in a confined space must be supplied with air for combustion as required by code and the requirements listed in this manual. MAINTAIN THE VENT OR VENT/COMBUSTION AIR SYSTEM IN STRUCTURALLY SOUND AND PROPER OPERATING CONDITION.
  • Page 29: Measure And Adjust Manifold (Outlet) Gas Pressure

    4 . Observe manometer gauge to measure outlet pressure of gas valve . To measure low-stage pressure on unit equipped with two-stage valve, disconnect wire from the HI terminal on valve . Be sure to reconnect wire . UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 30 6 .7 1 .2 3 .4 9001–10,000 2746–3045 2 .2 6 .4 1 .2 3 .2 Canada 0–2000 0–610 3 .5 10 .0 1 .8 5 .0 2001–4500 611–1373 2 .8 8 .1 1 .5 4 .1 UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 31: Measure And Adjust Manifold Gas Pressure-Elevation >2,000 Feet (>610 Meters)

    . Ensure that surface is clean and dry and affix label . 13 . Observe heater operation for at least one complete cycle to check for safe and proper operation . For models UBZ and UDZ, depress and hold safety door switch . UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 32 90,720 112,050 130,725 149,400 168,075 186,750 224,100 261,450 298,800 (611–1373) 27,000 40,500 37,800 47,250 66,150 75,600 94,500 110,250 126,000 141,750 157,500 189,000 220,500 252,000 A = normal input, B = thermal output capacity, and C = minimum input . UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 33: Maintenance

    ‰ Inspect burner/control compartment annually to determine if cleaning is necessary . ‰ Clean all dirt, lint, and grease from combustion air opening (models UBX and UDX) and venter assembly . ‰ Clean all dirt, lint, and grease from fan blade, fan guard, and motor .
  • Page 34 . Each baffle is held in place by one screw . (2) For correct re-assembly on secondary air shield, mark location (top and bottom) of each baffle . (3) Remove screw(s) and remove baffle(s) (all) . UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 35 . Leak test connection using leak detecting solution . If leak is detected, tighten connection . If leak cannot be stopped by tightening connection, replace part(s) . 6 . Turn ON electric and gas . 7 . Check for proper operation . UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 36: Burner Orifice Maintenance

    Inspect and clean the motor, fan guard, and blades . Remove any dirt and grease . Take care when cleaning the fan blades so as prevent causing misalignment or imbalance . Check to ensure that the hub of the fan blades is secure to the shaft . If necessary, replace the assembly as follows: UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 37 0.5 Inch (13 mm) Spacing with 0.334 Inch (8.5 mm) Spacing (±10)) Inches Millimeters Inches Millimeters 9/16 1-1/16 1-1/2 1-3/4 2-1/8 1-1/2 2-3/8 2-3/8 2-5/16 2-1/8 2-3/8 2-1/8 1-5/8 — 225, 250, 300 1-7/8 1-3/8 Figure 17 . UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 38: Venter Motor And Wheel Assembly Maintenance

    11 . Restore electric power to heater and turn ON gas . 12 . Follow instructions on lighting instruction plate to light heater . 13 . Check for proper heater operation . UNIT SIZE 125 UNIT SIZES 150–400 UNIT SIZES 030–100 Figure 18. Venter Motor and Wheel Assembly UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 39: Combination Gas Valve Maintenance

    If it is determined that the interlock door switch (see Figure 19) needs replacing, use only a factory-authorized Figure 11 . replacement part that is designed for the heater . For the approximate door switch location, see UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 40: Flame Rollout Switch Maintenance (Models Udx And Udz Unit Sizes 030-125 Only)

    MAINTENANCE—CONTINUED Maintenance Procedures—Continued Flame Rollout Switch Maintenance (Models UDX and UDZ Unit Sizes 030–125 Only) Figure 19) activating must be determined . Activation of the manually-reset • The cause of a flame rollout switch (see flame rollout switch could be caused by one or more of the following: a .
  • Page 41 Refer to thermostat manufacturer's instructions adjustment E . Fan 1 . Circuit open Check wiring and connections or venter 2 . Defective integrated circuit board Replace board motor will not run 3 . Defective motor Replace motor UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 42: Unit Troubleshooting Using Dsi Control Module

    Lockout from failed ignition or flame loss Pressure switch is not closed within 30 seconds of venter motor energizing Flashing Pressure switch is closed before venter motor is energized Limit switch or rollout open Undesired flame Polarity reversed Steady Internal fault/power failure UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 43 Figure 20. DSI Control Module Troubleshooting Flowchart UBX-UBZ-UDX-UDZ-IOM (07-23) 1034344-K...
  • Page 44: Installation Record (To Be Completed By Installer)

    Company Address Phone No. For more information on Reznor HVAC products: • Contact your local Reznor representative at 1-800-695-1901 • Refer to the technical specifications, manuals, and consumer materials found at www.reznorhvac.com Specifications and illustrations subject to change without notice or incurring obligations .

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