Reznor UBX - User Manual

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Revision: OPT-CL31-CL32 (11-21) 102247-A

RELAY KIT INSTALLATION FOR MULTIPLE HEATER CONTROL

Supersedes: I-OPT-MH (02-16) PN102247R8

OPTIONS CL31 AND CL32 FOR MODELS APD, F, B, LDAP, UBX, UBZ, UDAP, UDAS,

UDBP, UDBS, UDX, UDZ, UEAS, UEZ, AND VR

GENERAL INFORMATION

These relay kits are designed to permit the control of up to six heaters (one control unit and up to ﬁve additional non-

control units) with one single-stage thermostat or with a time clock and single or multiple single-stage thermostats.

For maximum safety, the multiple control is installed in the low voltage circuit. Interruption of the supply voltage is

not recommended.

Important Safety Information

• Refer to the installation manual provided with the heater for important safety information.

• Pay attention to all dangers, warnings, cautions, and notes highlighted in this manual. Safety markings should not

be ignored and are used frequently throughout to designate a degree or level of seriousness.

⚠ CAUTION ⚠

• DO NOT use these multiple heater control options with a two-stage gas valve or a two-stage

thermostat.

• These instructions are designed to assist a qualiﬁed electrician in installing this multiple heater

control kit.

• All electrical wiring and connections, including electrical grounding, MUST be in accordance with

the National Electric Code ANSI/NFPA No. 70 (latest edition) or, in Canada, with the Canadian

Electrical Code, Part 1, CSA Standard C22.1. In addition, the installation must comply with local

ordinances and applicable gas company requirements.

Applicability

Model/option/voltage applicability is listed in Table 1 and kit components are listed in Table 2. Ensure that all

components listed in Table 2 are available before beginning installation.

Table 1. Model/Option/Voltage Applicability

Model Voltage/Phase

Option for

Control Unit

Option for

Non-Control Unit(s)

No. of Non-Control

Units Permitted

APD, UBX, UBZ, UDAP, UDAS,

UDBP, UDBS, UDX, UDZ

115/1, 208/1, 230/1, 208/3, 230/3,

460/3, 575/3

CL31 CL32 4

F. B, VR

115/1 CL31 CL32

4208/1, 230/1, 208/3, 230/3, 460/3 CL32 CL32

575/3 CL31 CL32

LDAP 208/1, 230/1 CL31 CL32

UEAS, UEZ 115/1 CL31 CL32 4

*Except as follows: unit size 400 can have ﬁve (5) additional non-control units, unit size 800 can have three (3) additional non-control units,

and unit size 1200 can have two (2) additional non-control units.

Main Page

RELAY KIT INSTALLATION FOR MULTIPLE HEATER CONTROL: OPTIONS CL31 AND CL32 FOR MODELS APD, F, B, LDAP, UBX, UBZ, UDAP, UDAS, UDBP, UDBS, UDX, UDZ, UEAS, UEZ, AND VR1

Other manuals for Reznor UBX

Installation4 pages

Questions and Answers

B
Bryan WilliamsAug 25, 2025
How to troubleshoot a Reznor UBX Gas Heater venter motor that will not start?
- M
  Mary EstradaAug 26, 2025
  If the venter motor on your Reznor Gas Heater won't start, here are a few things to check: 1. Make sure the unit has power and check the supply fuses or circuit breaker. 2. Ensure the thermostat is turned up to provide 24V power to the integrated circuit board. 3. Check the control transformer output. 4. Replace the integrated circuit board fuse (3A, type ATC or ATO, 32VDC) after fixing the cause of the blown fuse. 5. Tighten connections at the circuit board and/or motor terminals to ensure power is reaching the venter motor. 6. If the integrated circuit board is defective, replace it. 7. If the venter motor is defective, replace it, referring to the Venter Motor and Wheel Assembly Maintenance section.
K
karenstevensonNov 8, 2025
What to do if the burner will not light on my Reznor UBX?
- C
  Chase SandersNov 8, 2025
  If the burner on your Reznor Gas Heater won't light, there are several potential causes and solutions: 1. Ensure the manual valve is open. 2. If it's the initial startup, bleed the gas line to remove air. 3. Verify the gas pressure is within the correct range: 5–14 IN WC for natural gas or 11–14 IN WC for propane. 4. Check for spark issues: * Make sure all wire connections are secure. * Confirm 24V power is available. * Maintain a 1/8 inch spark gap. * Replace any worn or grounded spark cables. * Replace the ceramic spark electrode if cracked or grounded. * Ensure the integrated circuit board is grounded to both terminals P1–9 and the furnace chassis. * Ensure the unit is properly field grounded to earth ground and properly phased (L1 to hot l...

This document outlines the installation procedures for Reznor Relay Kits, specifically options CL31 and CL32, designed for multiple heater control. These kits are compatible with various Reznor heater models, including APD, F, B, LDAP, UBX, UBZ, UDAP, UDAS, UDBP, UDBS, UDX, UDZ, UEAS, UEZ, and VR.

Function Description

The primary function of these relay kits is to enable the control of multiple heaters (up to six units) from a single control point. This control can be achieved using a single-stage thermostat or a time clock combined with single or multiple single-stage thermostats. The system is designed to manage one "control unit" and up to five "non-control units." The multiple control functionality is integrated into the low voltage circuit, ensuring enhanced safety by avoiding interruptions to the main supply voltage.

The relay kits facilitate the coordinated operation of several heaters, which is particularly useful in larger spaces requiring distributed heating. By centralizing control, the system simplifies temperature management and can contribute to energy efficiency by preventing individual heaters from operating independently and potentially inefficiently. The design ensures that the control logic is handled at a low voltage, minimizing electrical hazards and simplifying wiring compared to high-voltage control schemes.

Usage Features

The relay kits offer several usage features that enhance the flexibility and safety of multi-heater installations:

Multi-Unit Control: The core feature is the ability to control up to six heaters (one control unit and five additional non-control units) from a single thermostat or time clock. This is ideal for large commercial or industrial spaces where multiple heaters are deployed.
Single-Stage Thermostat Compatibility: The system is designed to work with single-stage thermostats, simplifying integration with common HVAC control systems. It is crucial to note that these options are not compatible with two-stage gas valves or two-stage thermostats.
Low Voltage Integration: The multiple control is installed in the low voltage circuit, which is a key safety feature. This design choice reduces the risk of electrical shock and simplifies troubleshooting within the control circuit.
Model-Specific Applicability: The kits are tailored for a wide range of Reznor heater models, ensuring broad applicability across different heating solutions. The specific components and installation steps vary slightly depending on the heater model and voltage/phase configuration.
Control Unit vs. Non-Control Unit Distinction: The system differentiates between a "control unit" (which houses the primary control logic and often a larger transformer) and "non-control units" (which receive commands from the control unit). This architecture allows for scalable and efficient control of multiple heaters.
Wiring Diagram Labels: Each kit includes a model-specific wiring diagram label (Item 4) that must be installed on the unit. These labels provide crucial information for connecting the relay (1A) to the TEW-type control wiring, ensuring correct installation and future maintenance. The labels also include checkboxes to designate the heater as a "PRIMARY HEATER" (control unit) or "SECONDARY HEATER" (non-control unit), aiding in system identification.
Transformer Replacement: For most models, the installation process involves replacing the factory-installed transformer on the control unit with a higher-capacity transformer provided in the kit. This ensures adequate power for the expanded control system.
Cable Clamps: Cable clamps (Item 3) are included to secure wiring, maintaining a neat and safe installation.
Wire Connectors: For specific models like VR, twist-on wire connectors (Item 5A) are provided for splicing connections, ensuring secure electrical contacts.

Maintenance Features

While the document primarily focuses on installation, several aspects contribute to ease of maintenance and long-term reliability:

Clear Installation Instructions: The detailed, step-by-step instructions, coupled with references to specific item numbers from the kit components (Table 2) and illustrative figures (Figure 1 and Figure 2), simplify the installation process. This clarity reduces the likelihood of installation errors that could lead to maintenance issues.
Safety Warnings and Cautions: The manual prominently features "DANGER," "WARNING," "CAUTION," and "NOTE" advisories. These warnings highlight critical safety information and potential hazards, guiding installers to perform the work safely and correctly, thereby preventing damage to the equipment or injury, which would necessitate maintenance.
Compliance with Electrical Codes: The instructions emphasize adherence to the National Electric Code (ANSI/NFPA No. 70) or the Canadian Electrical Code (CSA Standard C22.1), as well as local ordinances. This ensures that the installation meets regulatory standards, contributing to system reliability and reducing the need for corrective maintenance due to non-compliance.
Control Wiring Specifications: Table 3 provides detailed control wiring specifications, including maximum length and distance for different wire gauges. Adhering to these specifications is crucial for maintaining signal integrity and preventing voltage drop, which could affect the performance and longevity of the control system. This proactive measure minimizes future troubleshooting and maintenance related to wiring issues.
Wiring Diagram Label for Future Reference: The requirement to install a wiring diagram label (Item 4) on the unit is a significant maintenance feature. This label provides an immediate reference for the specific control wiring configuration, making future troubleshooting, repairs, or system modifications much easier for technicians. The label's placement in easily accessible locations (e.g., bottom rear corner of access panel, inside access panel, rear of burner box) ensures it can be readily consulted.
Post-Installation Check: The final step of restoring the system to service includes turning on gas and electric power, lighting the heater, and checking for proper operation. This immediate verification helps confirm that the installation was successful and that all components are functioning as intended, catching any potential issues before they become larger maintenance problems.
Qualified Electrician Requirement: The instructions explicitly state that "these instructions are designed to assist a qualified electrician in installing this multiple heater control kit." This ensures that the installation is performed by professionals with the necessary expertise, reducing the risk of improper installation and subsequent maintenance needs.
Component Identification: Table 2, which lists all relay kit components by item number, description, and part number, is invaluable for maintenance. If a component needs to be replaced, this table allows for quick and accurate identification of the correct part.