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Savings Project: Lower Water Heating Temperature

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Project Level 
Easy
Energy Savings 
$12-$30 annually for each 10ºF reduction
Time to Complete 
2 hours
Overall Cost 
$0
Turning down your water heater temperature can save energy and money. | Photo courtesy of iStockphoto.com/BanksPhotos

Turning down your water heater temperature can save energy and money. | Photo courtesy of iStockphoto.com/BanksPhotos

Although some manufacturers set water heater thermostats at 140ºF, most households usually only require them to be set at 120ºF, which also slows mineral buildup and corrosion in your water heater and pipes. Water heated at 140ºF also poses a safety hazard—scalding.

Savings resulting from turning down your water heater temperature are based on two components: reduced standby losses (heat lost from water heater into surrounding basement area); and consumption (from water demand or use in your home). Set too high, or at 140ºF, your water heater can waste anywhere from $36 to $61 annually in standby heat losses and more than $400 in demand losses.

If you have a dishwasher without a booster heater, it may require a water temperature within a range of 130ºF to 140ºF for optimum cleaning. And while there is a very slight risk of promoting legionellae bacteria when hot water tanks are maintained at 120ºF, this level is still considered safe for the majority of the population. If you have a suppressed immune system or chronic respiratory disease, you may consider keeping your hot water tank at 140ºF. However, this high temperature significantly increases the risk of scalding. To minimize this risk, you can install mixing valves or other temperature-regulating devices on any taps used for washing or bathing.

Source: Save Energy at Home, ENERGY STAR

Before You Start 
  • Consult your water heater owner's manual for instructions on how to operate the thermostat.
  • You can find a thermostat dial for a gas storage water heater near the bottom of the tank on the gas valve. Electric water heaters, on the other hand, may have thermostats positioned behind screw-on plates or panels.
  • As a safety precaution, shut off the electricity to the water heater before removing/opening the panels.
  • Keep in mind that an electric water heater may have two thermostats—one each for the upper and lower heating elements.
Shopping List 
  • Thermometer for testing the water temperature.
  • Marker to mark the setting on your thermostat

STEP-BY-STEP INSTRUCTIONS

  • 1.) Find the current temperature.
    Measure the beginning temperature of your hot water using a thermometer at the tap farthest from the water heater. Thermostat dials are often inaccurate.
  • 2.)  Mark the setting, then turn down the thermostat.
    Mark the beginning temperature on your water heater thermostat with a marker, and then turn the thermostat down.
  • 3.) Measure and adjust.
    Wait a couple of hours, and then measure the water temperature again at the farthest tap from the water heater. Several adjustments may be necessary before you get the temperature you desire.
  • 4.) Mark the new temperature.
    If you are satisfied with the temperature, mark the new temperature on the water heater thermostat with a marker, so that you can make adjustments in the future if necessary.
  • 5.) Turn down or off when away.
    If you plan to be away from home for at least 3 days, turn the thermostat down to the lowest setting or completely turn off the water heater. To turn off an electric water heater, switch off the circuit breaker to it. For a gas water heater, make sure you know how to safely relight the pilot light before turning it off.

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