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Smart Home

How to adjust the temperature of your water heater

Proper water heater temperature is about more than just comfort. It can save money and your skin.

Taylor Martin/CNET

No one likes a cold shower. Even worse is getting scalded when you run the hot water. Properly setting the temperature on your water heater is important not only for your health and safety, but also for saving money on your electricity bill.

Here is how to adjust the temperature on your water heater to save money and your skin.

The correct temperature range

There are a number of reasons your water heater should be set within a specific range of temperatures. If it's set too low, not only will your hot water feel lukewarm, at best, it can also lead to bacterial growth which can cause things like Legionnaires' disease.

This can be prevented by setting the water heater to a temperature where the bacteria Legionella cannot thrive. The Occupational Safety & Health Administration (OSHA) recommends water heaters be set to at least 140 degrees Fahrenheit (60 degrees Celsius) to minimize the growth of Legionella and other microorganisms.

While you might be prone to just crank up the heat, water that is too hot is potentially more dangerous, especially if you have kids around the house. At 150 degrees Fahrenheit (66 degrees Celsius), it only takes two seconds to suffer third-degree burns. The Consumer Product Safety Commission (CPSC) recommends setting the water heater at no more than 120 degrees Fahrenheit (49 degrees Celsius) to prevent scalding. Not to mention, a water heater that is set too high can unnecessarily increase your electricity bill.

Of course, every house is different. The further a faucet is from the water heater, the more heat will be lost as the water travels, especially if the pipes aren't insulated. That means you might have to raise the temperature beyond the recommended 120 degrees Fahrenheit (49 degrees Celsius) to compensate.

Use your best judgement for your family and household when setting the temperature. It's smart to stay within the range of 120 to 140 degrees Fahrenheit (49 to 60 degrees Celsius). Make an adjustment, test it out and repeat until you settle on the perfect temperature setting for you home and water heater.

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Adjusting water heater temperature

The interface for setting the temperature on a water heater will vary by type and model. Fortunately, most water heater types are adjusted similarly.

For instance, most newer gas and electric water heaters have a thermostat behind an insulated access panel. Electric water heaters often have two thermostats -- one at the top and another at the bottom of the tank. And most tankless water heaters feature a display with a temperature readout and controls for adjusting the temperature.

Regardless of the water heater type, you should test the water before you make any adjustments. Turn on the water in the bathroom or kitchen sink and let it run until it's fully hot. Then hold a thermometer under the water to get an accurate reading.

Tankless

Adjusting a tankless water heater is a lot like adjusting the thermostat for your air conditioning. Use the digital control panel to adjust the temperature up and down as needed.

Gas or electric water heaters

Some gas water heaters feature a dial near the bottom of the unit that you can simply adjust by turning it -- no tools required. However, most newer tank water heaters (gas or electric) are a little more involved, but it's still easy and should only take a couple of minutes.

  • Start by turning off power to the water heater at the circuit breaker.
  • Find the access panel for the thermostat(s) and use a screwdriver to remove the panel.
  • Peel back the insulation.
  • Use a flathead screwdriver to adjust the thermostat up or down.
    • If your water heater has two thermostats, adjust both the same amount. The top thermostat should be a few degrees higher than the bottom.
  • Replace the insulation and reinstall the access panel.
  • Restore power to the water heater.
  • For gas water heaters, you may need to relight the pilot light.

Once you've made an adjustment, wait at least three hours before testing the water temperature again. You may need to make additional adjustments to get the temperature just right.

If you've raised the temperature and you're still experiencing cold showers, your hot water heater may need to be serviced or even replaced.

Is your home energy efficient? Here are 5 ways to find out.

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