How to Set Your Water Heater Temperature

By Elana Duré

Many water heaters will have a sticker with instructions on how to set the water temperature, but if you’re without specific instructions or the owner’s manual, you can follow these four steps to set the temperature.

Safety considerations

The US Department of Energy suggests setting your water heater thermostat to 120°F. This temperature helps prevent scalding, saves energy, and slows mineral buildup and corrosion in your water heater and pipes.

There are a few conditions that call for higher water temperatures despite the risk of scalding.

If your tap water has an unpleasant odor, you could have a bacteria problem. Adjusting your hot water tank to 140°F for 24 hours should help rid the water of the bacteria. Be sure to tell family members the water temperature has been increased and keep children away from faucets.

If you have a suppressed immune system or chronic respiratory disease, you may consider consistently keeping your tank at this higher temperature. Or if you have an older dishwasher, which often doesn’t have booster heaters to preheat water, consider keeping your water heater temperature at 130°F or 140°F to ensure sanitary dishes.

If you do keep your water heater at a higher temperature, and especially if you have children or older family members in your home, you can install mixing valves or other temperature-regulating devices on taps used for washing or bathing to minimize the risk of scalding.

How to set your water heater temperature in 4 steps

1. Familiarize yourself with your heater

The thermostat dial for a gas water heater is located near the bottom of the tank by the gas valve.

If you have an electric water heater, shut off the electricity to the water heater before opening the plates. Electric water heaters have thermostats behind screw-on plates or panels. Keep in mind that an electric water heater may have two thermostats—one for the upper heating element and one for the lower.

Before adjusting the dial, alert everyone in your house to avoid using the taps.

Materials

  • Vessel for hot water—drinking glasses, coffee mugs, or pots work well
  • Cooking or candy thermometer
  • Permanent marker

2. Mark the initial temperature

It’s important to know the temperature of the water in your home before adjusting the thermostat.

    1. Allow your water heater to sit for an hour unused before checking the initial temperature.
    2. After an hour, run hot water at the tap closest to the water heater for at least three minutes.
    3. Then fill a glass, mug, or pot with the hot water and check its temperature using a cooking or candy thermometer.
    4. Mark the beginning temperature on your water heater thermostat with a permanent marker.

3. Test the water temperature

    1. Once you’ve marked the initial temperature, you can adjust the dial to 120°F or to your preferred temperature.
    2. Wait about three hours and then check the water temperature again using the above method.
    3. Several adjustments may be necessary until you reach your desired temperature.

4. Label dial

Once you’re satisfied with the new temperature, mark it on the dial for future adjustments. For the final test, check the temperature the next morning before anybody uses the hot water.

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