Heat-Only HVAC Wall Thermostat For: White-Rodgers Lux 1C20-101 1C20-102 PSM200 PSM90 255-401 255-40A 9204H ER9204H

ERP 9204H Heat-Only HVAC Wall Thermostat

This ERP aftermarket horizontal mechanical wall thermostat is designed for compatible single-stage gas or electric heating systems. It provides heat-only SPST control for low-voltage HVAC applications and is not a line-voltage baseboard thermostat. Verify the complete heating system, wiring, voltage, terminal configuration, and anticipator requirements before ordering.

Product Details

• Product type: Horizontal mechanical heat-only wall thermostat.
• Compatible application references: White-Rodgers and Lux.
• Control: Single-stage heat-only SPST.
• Electrical rating: 24 VAC, 2 A maximum.
• Dial range: 50–90°F.
• Millivolt compatibility may apply when the required anticipator setup is used, as specified by the manufacturer.
• Not for line-voltage baseboard or other high-voltage circuits.
• SKU / ERP identifier: ER9204H.
• Primary part number: 9204H.

Cross-Reference Part Numbers

• 1C20-101
• 1C20-102
• PSM200
• PSM90
• 255-401
• 255-40A
• 9204H
• ER9204H

Brand names and cross-reference numbers identify compatible applications or referenced components. This ERP part is not represented as a genuine OEM product. Match the original thermostat, full equipment model, wiring, control type, and configuration before ordering.

What This Thermostat Is Designed To Do

• Control a compatible single-stage heat-only call.
• Provide manual temperature control through the mechanical dial.
• Replace a matching low-voltage wall thermostat that is worn, damaged, or no longer responding correctly.
• Support compatible gas, electric, or manufacturer-specified millivolt applications when installed with the required anticipator setup.

Fixes These Symptoms

• Heating system does not start when the thermostat calls for heat.
• Heating system runs continuously after the set temperature is reached.
• Thermostat dial or contacts are worn, damaged, or unreliable.
• Temperature control is inaccurate or inconsistent.
• Heat call is intermittent after the HVAC wiring and equipment are confirmed.

These symptoms can also be caused by the furnace, boiler, gas valve, wiring, transformer, fuse, limit control, or other heating-system components. Diagnose the system before replacing the thermostat.

Compatible Brands and Models

Compatible application references: White-Rodgers and Lux.

Fits various models. Please verify compatibility with us before ordering. Similar appearance or part-number similarity alone does not establish fitment.

Before Ordering

• Confirm the system is heat-only and single-stage.
• Confirm the circuit is low voltage and matches the 24 VAC, 2 A maximum rating.
• Confirm whether the application is gas, electric, or manufacturer-specified millivolt and follow the required anticipator setup.
• Compare the original thermostat terminals, mounting footprint, and control type.
• Do not use this thermostat on a line-voltage baseboard or other high-voltage circuit.

Installation and Safety

1. Disconnect HVAC control power before service and verify the circuit is de-energized.
2. Photograph and label the original wires by terminal position. Never infer connections from wire color.
3. Follow the manufacturer terminal diagram and anticipator instructions for the exact application and control revision.
4. Do not jumper gas-valve or system-control terminals to test the system.
5. Mount the thermostat securely, restore power, and run a supervised heating-cycle test.
6. Use a qualified HVAC technician when wiring, system voltage, millivolt operation, or compatibility is uncertain.

This is preparation guidance, not a complete model-specific repair procedure. Review the manufacturer documents for qualified service and confirm their scope before installation.

Prop 65 Warning: Cancer and Reproductive Harm – www.P65Warnings.ca.gov

Manufacturer installation manual

Manufacturer product/application reference