Rheem Water Heater Pilot Won’t Stay Lit — What’s Happening
A pilot that lights but will not stay lit means the safety circuit is opening after ignition. The pilot flame must heat the thermocouple or thermopile so the gas valve stays open. If that flame signal is too weak or interrupted, the gas control shuts down the pilot circuit and the flame goes out.
This symptom is not a fault code. It tells you that something is preventing the flame-proving device from holding the gas valve open long enough to keep pilot gas flowing. The problem can be at the flame sensor itself, the pilot orifice, the gas supply, the ventilation path, or inside the gas control valve.
Most Likely Causes
- Defective or dirty thermocouple or thermopile The flame sensor is covered in soot, misaligned, corroded at the connection, or has failed internally so it cannot generate enough signal to hold the valve open.
- Blocked pilot tube or pilot orifice Dust, spider webs, or debris restrict gas flow to the pilot so the flame is weak, flickering, or unstable and cannot heat the sensor properly.
- Tripped thermal release device or rollout switch A thermal cutoff or rollout safety has popped due to overheating or blocked venting and breaks the safety circuit until it is reset or replaced.
- Drafts or inadequate combustion air Air currents blow the pilot flame off the sensor, or poor ventilation causes the flame to lift or go out before the thermocouple heats up.
- Low or inconsistent gas supply The supply valve is partly closed, the regulator pressure is wrong, or an LP tank is nearly empty so the pilot cannot establish a steady flame.
- Loose or corroded thermocouple connection The thermocouple lead is not tightened at the gas valve or has corrosion at the terminal, interrupting the millivolt signal needed to hold the valve.
- Failed gas control valve If all flame-proving parts test good and the pilot assembly is clean, the internal valve or safety circuit in the gas control is likely defective and the entire control must be replaced.
How to Diagnose and Fix
- Shut off the gas supply at the appliance shutoff valve and wait five minutes for any residual gas to clear before opening the burner compartment.
- Verify that the main gas shutoff to the water heater is fully open and, if the unit runs on propane, confirm the LP tank has adequate fuel.
- Look through the viewing window or burner door at the pilot flame while it is lit (if it stays lit briefly). A healthy pilot is steady and blue. A weak, yellow, or flickering flame points to a blocked orifice, draft, or gas pressure problem.
- Inspect the thermocouple or thermopile at both ends for loose connections, corrosion on the terminals, or misalignment in the pilot flame, and tighten or clean the connections as needed.
- Remove the pilot assembly if accessible and clean the pilot tube, pilot orifice, and the thermocouple or thermopile tip with a soft brush or compressed air to remove soot, dust, and spider webs.
- Check the burner compartment and flue baffle area for signs of rollout or soot, and look for a popped thermal release device or thermal cutoff button that may need to be reset or replaced.
- Relight the pilot following the manufacturer’s lighting procedure on the label, hold the pilot button for the full 60-second period, then release and confirm the pilot stays lit on its own.
- If the pilot still drops out after cleaning and connection checks, the gas control valve or an integrated safety control is the next suspect and typically requires professional replacement.
Parts You Might Need
| Part | Notes |
|---|---|
| Thermocouple or thermopile | Amazon | Flame sensor that holds the gas valve open. Match the lead length and thread size to your Rheem model. |
| Gas control valve or thermostat assembly | Amazon | The main gas valve with integrated pilot safety. Replacement requires a gas-qualified technician and matching part number. |
| Thermal release device (TRD) or rollout switch | Amazon | Safety cutoff that opens on overheat. Some are manual-reset buttons, others require part replacement. |
Related Error Codes
If your appliance also shows a code on the display, these match this problem:
When to Call a Pro
Call a licensed plumber or gas technician if you are not comfortable working around gas appliances, if cleaning and connection checks do not solve the problem, or if you suspect the gas control valve has failed. Gas control valve replacement, thermopile testing with a multimeter, and any work on the gas supply line or vent system should be handled by a qualified professional. If you smell gas at any point, leave the area immediately and call your gas utility or emergency services. For gas line, burner, or igniter work, or if you ever smell gas, stop and call a licensed technician.