The White Rodgers 37C73U is a thermostat control for natural gas water heaters, featuring fixed adjustment main and pilot regulators that automatically control and maintain outlet main and pilot burner gas pressure. It includes a temperature dial for setting desired water temperature (recommended ~120°F), tamper-resistant screws, and knob positions: OFF, PILOT, ON. Designed for professional installation only, compatible with natural gas systems. Below are the key specifications, installation, operation, and troubleshooting instructions.
Assemble tools: flat blade screwdriver, adjustable wrench, soapy water solution for leak testing, hose for draining. Shut off gas to the water heater. Shut off water at the cold water inlet. Connect a hose to the heater drain cock and drain water to a nearby drain. Open a hot water faucet to speed up draining. Professional installation required.
WARNING! Failure to read and follow all instructions carefully before installing or operating this control could cause personal injury and/or property damage. Save these instructions.
The White Rodgers 37C73U is a thermostat control for water heaters, designed for natural gas only. It features fixed adjustment main and pilot regulators that automatically control and maintain outlet main and pilot burner gas pressure. The control includes a temperature dial to set the desired water temperature, with a recommended setting at the arrow for approximately 120°F output.
Applications: Natural Gas Water Heaters Only; Not for LP Gas.
CAUTION! Installation or service must be performed only by a professional. Do not use force on the gas control knob; replace the control if it cannot be turned by hand. Ensure the knob "pops up" after being depressed in the PILOT position; replace if it does not. Do not attempt to repair or adjust the control; replace it immediately if problems occur. Check for gas leaks using a soapy water solution, not a match or open flame. Do not use this control on an LP gas water heater; it is for natural gas only. Install a gas detector if unodorized gas is suspected, as odorants may not always be present. Lower temperature settings reduce the risk of scald burns and save fuel.
WARNING! Do not use on LP gas; risk of CO poisoning, fire, explosion. If smell gas: Do not light appliances, no switches/phones, call gas supplier/fire dept. Check for leaks with soapy water, not flame.
Shut off gas to water heater. Shut off cold water inlet. Connect hose to drain cock, drain to nearby drain; open hot faucet. Remove outer door. Pull off control knob. Remove screws holding thermostat to gas control. Disconnect wires from old control. Remove old control from gas control.
Shut off gas and drain water as above. Remove old control. Install new 37C73U: Connect gas lines, wires, manifold. Check for leaks with soapy water (supply line, control to manifold, pilot tube). Affix new lighting label over old. Restore water, light pilot.
Terminal Designations: Wires to gas control valve; igniter connections.
Gas Connections: Inlet to gas supply, outlet to manifold, pilot tube to burner. No electrical wiring beyond igniter.
CAUTION! Test all connections for leaks before lighting. Use soapy water only.
After installation, ensure the pilot light ignites and the main burner operates correctly. Verify that the temperature dial regulates water temperature as expected. Confirm that the control knob functions properly (e.g., pops up in PILOT position).
Not applicable; water heater control without fan.
Not applicable; water heating only.
Non-programmable mechanical control. Set temperature via dial after lighting pilot.
No specific installer configuration steps are detailed in the content.
| Symptom | Possible Cause | Corrective Action |
|---|---|---|
| If the gas control knob cannot be turned by hand | Damaged mechanism. | Replace the control. |
| If the knob does not "pop up" in the PILOT position | Damaged spring. | Replace the control and shut off gas. |
| If gas leaks are detected (bubbles in soapy water solution) | Loose connections. | Shut off gas and contact a professional. |
| If the control malfunctions | General failure. | Replace it immediately to avoid fire or explosion risks. |