Reliance Thermostat Stuck Closed or Set Too High

Water is too hot from Reliance water heater (scalding at taps)

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Thermostat temperature set above 120°F, Failed thermostat contacts welded closed, Miswired thermostat, Defective gas control thermostat

How to Fix / Troubleshooting

Safety first: Risk of scalding. Warn household members and consider lowering the temperature at mixing valves temporarily. For electric units, turn OFF power before opening panels; for gas, set control to PILOT or OFF.

Steps to check:

  • 1. Check set temperature: For electric models, remove access panels and read the dial setting on upper and lower thermostats. For gas models, check the temperature dial on the gas control. Adjust to about 120°F.
  • 2. Monitor temperature: After adjustment, allow several hours and then measure hot water temperature at a faucet with a thermometer. If still excessively hot, suspect a faulty thermostat.
  • 3. Replace thermostat (electric): With power OFF, label and remove wires from the suspect thermostat and install a new Reliance-compatible thermostat. Set to 120°F.
  • 4. Replace gas control (gas): If the gas control does not respond to temperature changes or overshoots, the entire gas control valve/thermostat assembly must be replaced.
  • 5. Consider mixing valve: Install or service a thermostatic mixing valve at the heater outlet to provide stable, safe delivery temperatures.

Warning: Children and elderly are especially vulnerable to scalding. Address over-temperature issues promptly.

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Repair Difficulty

Medium 3/5

Required Part

Thermostat / Gas Control Valve
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