How to Set How Water Heater Temperature by Thermostat

Need to know how to set your hot water heater temperature setting? Below find everything you need to know about your gas or electric water heater thermostat, what temperature is best for hot water, and how to set your hot water heater temperature thermostat.

What’s the Right Temperature for a Hot Water Heater?

It’s a common question: what temperature is best for hot water? The U.S. Department of Energy recommends setting a tank-based hot water heater to 120 degrees Fahrenheit. If you have never adjusted your hot water heater temperature, it’s most likely set on the default setting for most manufacturers of hot water heaters, which is 140 degrees Fahrenheit.

Why is following this temperature standard important? If the water heater thermostat setting uses too high a temperature setting, the water will be too hot and could cause burning or scalding. If it’s set too low, it could be conducive to bacteria, causing water-borne diseases.

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How to Set Your Hot Water Heater Temperature Thermostat Setting

Before you make any adjustments to your hot water heater temperature thermostat setting, determine what your current temperature is set at so you’ll know how much you need to adjust the settings. You can use any standard cooking thermometer to determine the temperature easily.

Once you’ve determined the current temperature setting, calibrate your thermometer. To do so, place your thermometer in a cup of iced water until the temperature dial lowers to 32 degrees, or the lowest degree on your thermometer’s gage. Calibrating the thermometer essentially resets it so that you will get an accurate temperature reading moving forward.

While you calibrate your thermometer, find the faucet located closest to the water heater and run it until it’s hot. Be careful! If your temperature is set too high, it may be hot enough to burn you. Once the water is hot, fill a cup and get the temperature by placing your thermometer in the water.

Adjusting a Gas Hot Water Heater Temperature Thermostat Setting

The majority of gas water heaters are simple because they have an easily readable dial located at the bottom of the tank. To adjust this dial is simple and easy if you follow the steps below.

  1. First, turn the knob towards being hotter or cooler, depending on what setting is necessary.
  2. After doing this, water several hours (about three or four) and retest the temperature.
  3. If it’s still the wrong temperature, adjust again and repeat the steps until it’s corrected. Need help? Give Hackler Plumbing a call if you need a McKinney plumber, and we can help!

Adjusting an Electric Hot Water Heater Temperature Thermostat Setting

Adjusting an electric hot water heater temperature thermostat setting is a little more involved, but still relatively easy. The majority of electric water heaters have two thermostats: an upper and a lower, located under two control panels.

To ensure your electric water heater works as efficiently as possible, you should set both of the thermostats at the same temperature. Note: some smaller electric hot water heaters only have one thermostat.

Here’s how to adjust the temperature on your electric hot water heater thermostat:

Note: You’ll need a screwdriver to complete the following steps to adjust your water heater thermostat setting.

  1. Turn off the power to your water heater. You can do this by locating your circuit breaker and turning off the power in the vicinity of your water heater.
  2. Next, locate the thermostat(s) on your water heater. Usually, these are under a control panel that’s attached with screws. Use your screwdriver to remove the access panel cover(s). If your heater is insulated, you may need to remove the insulation to access the thermostat. The thermostats will have a dial, and these dials can read differently depending on the manufacturer of the heater.
  3. Once you have removed the control panel, adjust the temperature dials to be hotter or cooler based on your temperature needs. Make sure that if you have two thermostats to adjust both to be the same temperature setting.
  4. Replace the control panel covers and replace the screws with your screwdriver. Then, turn the power to your water heater back on.
  5. Retest your hot water temperature after several hours (about three to four). If your water temperature is still not at the desired setting, repeat the above steps to readjust until it reaches the correct setting for your needs.

Other Considerations: Water Heater Thermostat Setting Safety

A special note: your water heater is equipped with something called a temperature and pressure relief valve, or a “T&P valve.” These can wear out over time, and one indication of the need for replacement is water seeping out. This is an important safety mechanism. If your unit is old, or if your hot water heater pressure relief valve is leaking after replacement, have it checked by a licensed plumber.

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