How To Change The Temperature On A Hot Water Heater

By Subodh / April 27, 2013

Hot water heaters found in a residential home that are set too high often lead to higher energy costs with the potential for injury. If the hot water heater is set at 140 degrees, then burns may occur within a span of five seconds. Water set at a temperature of 120 degrees needs up to five minutes to cause burns. This means a reduction in the temperature of a hot heater is beneficial for safety and energy reduction. If the temperature of the hot water heater in your home is too high, then a series of steps needs to be followed to make an adjustment.

Check Water Temperature

This is the first step that is required to determine the current temperature of the water. The best way for you to do this is to use a cooking thermometer. Run the hot water from a nearby tap until you know the water is fully hot. Place the thermometer in a glass and then fill it with hot water. If the hot water in the house was recently used, then wait at least two hours before checking the temperature. The wait allows the hot water heater to sufficiently reheat the water.

Calculate Temperature Reduction

The next step is to record the temperature that is on the thermometer. The reading should be between a value of 130 degrees and 160 degrees. Subtract 120 from the reading on the thermometer. The result of the calculation is the temperature reduction that needs to be applied to your water heater. Electric Water Heater

Electric Water Heater

These units are controlled by a thermostat located behind an access panel. The thermostat location on a hot water heater is under a metal plate or cover and may be surrounded by insulation. Electric hot water heaters often have two thermostats.

  1. You will need to remove the access panels on your hot water heater by using a screwdriver.
  2. Pull away any insulation and the thermostat should be visible. Read the dial on the thermostat to determine the current setting.
  3. Adjusting the temperature setting can be done using the screwdriver or turning the dial to 120 degrees.
  4. Replace the insulation and set the access panels back on the unit.

Gas Water Heater

A gas water heater will use a burner to heat the water. The burner is controlled by a thermostat that will be located near the burner opening on the outside of the heater. Hot water heaters that use gas may be a conventional unit or a tankless unit. Conventional units are older and may have a temperature that is set too high.

  1. Locate the thermostat control or indicator and record the current temperature.
  2. Determine if you need to adjust the temperature to a lower level by performing the reduction calculation.
  3. Adjust the knob on the thermostat control to change the temperature.

Recheck Water Temperature

Allow the hot water heater to run normally for at least two days. This is enough time to circulate all the water in the tank and to attain the new temperature. Repeat the temperature test from a hot water tap. If you check the temperature too soon, then the reading may be incorrect.

Additional Information

Electric hot water heaters may have live wires connected to the thermostat. If you see wires attached to the thermostat, then turn off the breaker for the water heater at your circuit panel. Running out of water after making a change is a sign that too much water is being used. One way to correct this is to use less water or turn up the thermostat five degrees to see if more hot water is available.