Symptoms
- Hot water at the tap feels scalding within seconds
- Thermostat dial or display shows a high setting
- May have recently had the tank serviced or replaced
- No fluctuation, just consistently very hot
Likely causes
- CommonThermostat set above a safe levelMany tanks ship set higher than the recommended 120°F and are never adjusted after installation.
- PossibleMalfunctioning thermostat not regulating temperature accuratelyA faulty thermostat can let the water run hotter than its dial setting.
- PossibleMixing valve at the tank or fixture not installed or miscalibratedAnti-scald mixing valves, if present, can fail or be adjusted incorrectly.
What to do
- Turn off power (electric) or set the gas control to pilot before adjusting an electric thermostat, or simply turn the gas dial down for gas units.
- For electric units, remove the access panel and use a flat screwdriver to adjust the thermostat dial to around 120°F.
- For gas units, turn the temperature dial on the control valve down to the 'low' or 120°F marking.
- Wait several hours for the tank to adjust to the new setting before testing water temperature at a tap.
- Use a kitchen thermometer to check the actual tap water temperature rather than relying on the dial alone.
- If temperature stays scalding despite a low dial setting, the thermostat itself may be malfunctioning.
Tools and parts
- Flathead screwdriver
- Kitchen thermometer
When to call a pro
If the water stays too hot despite a properly lowered thermostat setting, have a plumber test and replace the thermostat.
Safety
Use caution
Water above 120°F can cause serious burns in seconds, especially for young children and older adults; always verify the actual tap temperature after adjusting.