What does ABC mean on a water heater?

Author: Dagmar Johnston  |  Last update: Wednesday, July 30, 2025

C - 150° F - About 1-1/2 seconds. B - 140° F - Less than 5 seconds. A - 130° F - About 30 seconds. HOT - 120° F - More than 5 minutes. LOW - 80° F - No hazard.

What level should a water heater be on ABC?

The next highest setting is usually either labeled as “Hot” or with a triangle, and this setting should correspond to 120 degrees. From there, you will typically see three higher settings marked either as 1, 2, and 3 or A, B, and C that correspond to 130, 140, and 150 degrees, respectively.

Should water heater be set to A or B?

They relate to the relative temperature of the hot water. C is hotter than B which is hotter than A. So if B is too hot, set it to A; if B is too cool, crank it up to C. Generally, A should be as hot as you need, but habits vary.

What is the best setting for a hot water heater?

120 degrees Fahrenheit is the safety recommendation against scalding, but 140° is the common default setting. Most experts agree that anything below 120 degrees creates a risk for bacteria to develop inside your water heater from stagnant water, such as legionella that causes Legionnaire's disease.

What mode should my water heater be on?

So, what is the best temperature range for your water heater? The EPA recommends 120 degrees because it's hot enough to keep diseases at bay but not hot enough to cause scalding. This setting will also supply enough hot water for most small families and is relatively energy efficient.

Water Heater Temperature Setting - Honeywell Gas Control

What temperature should my hot water tank be set at?

The recommended setting for this control is 60°C/140°F. (Storing hot water at temperatures of less than 55°C is not advisable due to potential for Legionnaires disease). If the water coming out of your taps is too hot then check this control as it could be set too high.

Why is my water not getting hot?

A lack of hot water can be caused by a variety of issues. In electric water heaters, a power loss or heating element failure can cause water to no longer heat in the tank. In gas water heaters, a faulty gas connection, a bad pilot light, or a bad burner can cause no water to heat.

What temperature is the C setting on a water heater?

C - 150° F - About 1-1/2 seconds. B - 140° F - Less than 5 seconds. A - 130° F - About 30 seconds. HOT - 120° F - More than 5 minutes.

Is 130 too hot for a water heater?

The best temperature setting for a hot water heater is between 120 and 140 degrees. Below 120 degrees, bacteria can develop in the stagnant water sitting in the tank. Above 140 degrees, the water is so hot that you and your family members can be at risk for scalding in as little as two seconds.

Does turning up the water heater make hot water last longer?

Raising the temperature setting on your water heater ultimately makes your hot water supply last longer. It will ensure everyone gets a hot shower, with plenty leftover to run your dishwasher and washing machine.

What letter should you set your water heater to?

The best setting for gas water heaters is around 115 to 120 degrees Fahrenheit. Oftentimes, water heaters will have additional options to either lower or increase the temperature of the water inside.

How often should I flush my water heater?

Most homeowners should flush their water heaters every 6 months or so, but if you have extremely hard water, you may want to do it more often. Flushing your hot water heater could be necessary as often as every few months depending on the mineral content of your local water supply.

What temperature should hot water be for shower?

According to most dermatologists, the ideal shower temperature is anywhere between 98°F (37°C) and 104°F (40°C)—and no more than 105 °F (41°C). Rinsing under lukewarm water allows you to stay comfortable and maintain your body temperature while reaping all the benefits of both hot and cold showers.

Should water heater be on A or B?

These are usually labeled A, B, C or 1, 2, 3, and the last setting is always “Very Hot.” The A or 1 setting should be around 130 degrees, B or 2 is 140 degrees, C or 3 is 150 degrees and “Very Hot” is always 160 degrees. Again, we never recommend setting the unit above the B or 2 setting to prevent scalding.

What is the ABC mode on a water heater?

That should be plenty hot enough for most uses in your home. Now, some water heater temperature controls come with settings that read “A-B-C” as opposed to numbers. Generally, A means 120 degrees, B means 130 degrees, and C means 140 degrees. Refer to your water heater's manual to confirm these settings.

Is 140 too hot for a water heater?

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.

Can you shower in 130 degree water?

According to Centers for Disease Control and Prevention (CDC), water temperatures ranging from 130 to 140 degrees Fahrenheit(°F) can eliminate most of the harmful bacteria. However, be warned that these high temperatures can also increase the risk of scalding.

What is the best temperature to set your water heater at?

Manufacturers often recommend a hot water heater temperature between 120 to 140°F, and there's a reason for this. The Occupational Safety and Health Administration (OSHA) recommends a recommended hot water temperature of at least 122 degrees to prevent the growth of harmful bacteria.

Does lowering water heater temperature save money?

Though the DOE says you can save money on hot water by lowering the maximum temperature of your water heater from 140° F to 120° F, we don't necessarily recommend it. That's because the lower temperature might invite opportunistic bacteria—including Legionella, associated with Legionnaires' disease—to proliferate.

What temperature kills bacteria in a water heater?

It takes only 32 minutes on average for Legionella to die at temperatures of 140 degrees, and at 151 degrees, the bacteria will die instantly. This is why disinfection that uses temperature change will set a water heater to approximately 158 degrees for five minutes.

What temperature is Legionnaires disease in water?

What is legionella? Legionella bacteria is commonly found in water. The bacteria multiply where temperatures are between 20-45°C and nutrients are available. The bacteria are dormant below 20°C and do not survive above 60°C.

How long do hot water heaters last?

While today's water heaters are better designed than older models, they still require regular maintenance in order to prolong their lives. With regular inspection, draining, and flushing, you can expect a gas water heater to last anywhere from 8-12 years and an electric water heater to last anywhere from 10-15 years.

What are the symptoms of a bad thermostat on a hot water heater?

Signs Your Water Heater Thermostat Is Faulty
  • You have no hot water.
  • You're running out of hot water quickly.
  • The water is too hot.
  • It takes a long time for your water heater to heat the water.
  • You keep having to reset the high-temperature limit switch.

Why is my hot water only warm?

As water collects inside your hot water heater to be heated, it's common for debris in the water—like sand, dirt, and minerals—to settle at the bottom of the tank. As the particles collect on the bottom of the tank, the water heater can't effectively heat your water, resulting in lukewarm water only.

How do I reset a water heater?

The reset button is typically located near the water heater thermostat. You will need to use a screwdriver to remove a cover plate to access the thermostat and reset the button. There may be insulation packed around the thermostat.

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