American Water Heaters Overheating / Thermostat Out of Calibration

Water temperature is too hot; risk of scalding at fixtures.

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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 set too high, Stuck thermostat contacts, Failed mixing valve (if installed), Cross-connection in plumbing

How to Fix / Troubleshooting

Safety: Hot water above 120°F can cause scalding. Adjust settings carefully.

  • 1. Lower thermostat setting: Set gas control or electric thermostats to approximately 120°F and wait several hours to stabilize.
  • 2. Test thermostats: If water remains excessively hot, replace the gas control valve (gas) or thermostats (electric).
  • 3. Check mixing valve: If a thermostatic mixing valve is installed at the heater outlet, verify operation and replace if it is stuck.
  • 4. Inspect plumbing: Look for cross-connections (e.g., single-handle faucets) that may affect temperature control.
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Repair Difficulty

Medium 3/5

Required Part

Gas Control Valve or Thermostats
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