Setting Your Hot Water Heater Thermostat

    hot water heater thermostat

    When you have a tank hot water heater, it works by keeping a reserve of water heated at all times for your convenience. Most manufacturers adjust the thermostat to a default of 140 degrees, which is actually too hot for most residential needs. Set your hot water heater thermostat to provide 120 degree-water and you'll save energy and money. Just follow this simple step-by-step guide.

    NOTE: If you have an older dishwasher, check the owners' manual. Without a heat booster, you may be only be able to set your hot water heater thermostat to 130 degrees. Most new dishwashers can clean using 120-degree water.


    Save Money: According to the US Department of Energy, for each 10-degree reduction in water temperature, you save 3-5 percent in energy costs, which adds up quickly. Also, if you're going on vacation, why expend energy having the water heater warm up water that will not be used? Turn your heater thermostat off altogether till you return, or at least set it at the lowest temperature.

    Go Green: You will cut out over 170 pounds of carbon dioxide emissions every year by lowering your water heater tank temperature from 140 down to 120 degrees.

    Preserve Plumbing: If your hot water heater thermostat is set to 120 degrees, it will slow down mineral buildup (lime scale") and corrosion in your water heater and plumbing pipes, extending the life of both.

    Safety: Setting your hot water heater thermostat to 120 degrees helps protect against scalding accidents. This should be on every parent's childproofing checklist.


    Anyone who can hold a screwdriver can perform this simple project. For a gas hot water heater, make sure you know how to safely relight the pilot light. Of course, it's best to consult your owners' manual, but if you don't know where it is, this is a general how-to for setting your hot water heater's thermostat. If you're really not the DIY type, find a handyman to take care of this adjustment for you.

    1. Turn off the circuit breaker for the water heater at the electrical box. If it is not listed on the location sheet inside of the panel, be on the safe side and turn off all the power.

    2. Remove the access panel on the water heater with a screwdriver.

    3. Carefully take off the hot water tank's insulation.

    4. There may be an upper and a lower heating unit, in which case there will be two thermostats behind two panels. Both will need resetting.

    5. The US Department of Energy suggests that homeowners check water temperature at the faucet farthest from the heater. Adjust with a screwdriver till the desired tap temperature of 120 degrees is reached.

    6. Replace the insulation and access panel.

    7. Turn the hot water heater's circuit breaker on.

    Setting the hot water heater thermostat to produce 120-degree water is an easy way to save money and energy, as well as keep your family safe.

    Updated March 4, 2018.

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