The Best Temperature for the Water Heater and Why?

Do you want to find out if your water heater is set to the right temperature?

In general, keeping your thermostat setting at 120 F is recommended – such water won’t cause scalding yet it’s hot enough to destroy the majority of bacteria. Leaving the temperature at 120 F will also help you save on your energy bills (there won’t be too much standby heat loss).

What Is the Best Temperature for the Water Heater and Why?

The Department of Energy recommends keeping the water in your water tank at 120 F.

Even though there is a very slight risk that some bacteria would be able to survive in such water, this temperature is considered perfect for the majority of households as it won’t lead to scalding and helps you save quite a lot of energy on water heating.

What Is the Ideal Temperature for Domestic Hot Water?

Once again, 120 F is the ideal temperature to avoid the possibility of scalding.

The default setting in a lot of water heaters is 140 F. And you can leave it that way, if…

  • You have a dishwasher without a booster heater. 120-degree water won’t be able to provide optimum cleaning.
  • Someone in the family has a suppressed immune system. Even though 120 F is enough to keep the majority of people healthy, immunosuppressed individuals can get harmed by the bacteria that have been ‘left behind’.
  • You have a large family. There might not be enough hot water for everyone if you keep the heater at 120 F (however, this might not be the case, if you have a highly efficient unit).

Read: What Is Water Heater Heat Pump? Everything You Need To Know

What Is the Maximum Temperature for a Hot Water Heater?

The temperature range on a lot of residential heaters is from 90-120 F to around 150 F.

But that does not mean that you should keep the thermostat set to the highest possible temperature.

You might get a third-degree burn if your skin gets exposed to 150-degree water for only 2 seconds. Even the 120-degree water can burn you if you stay under it for over 5 minutes.

Should You Lower Your Water Heater’s Temperature?

While a lot of homeowners might be tempted to bring their water heater’s temperature up to the maximum (to make sure that all bacteria are killed), lowering the temperature might actually be a better decision.

  • If the water in your heater is above 120 F, it will accelerate the accumulation of mineral sediment.  This will lead to tank corrosion, a shorter service life, and higher energy bills as it takes much longer to heat the water up if the tank has a lot of buildup in it.
  • Even the water at 120 F can cause scalding if you let it touch your skin for too long. Do bear in mind that the higher the temperature, the bigger the risk of scalding.140-degree water can damage your skin in as little as 5 seconds. Such hot water is especially dangerous for the elderly and small children who wouldn’t be able to react as fast to hot water.
  • Finally, the hotter the water, the faster it loses heat. The hot water that is stored in the tanks cools down and then the unit relights the burner to bring it back to the set temperature.You’ll save up to 15% (on standby heat loss alone) if you lower the temperature of your water heater from 140 F to 120 F.

Read: Ideal Temperature Of The Water Heater

How Do I Adjust the Temperature on My Gas Water Heater?

Unfortunately, the thermostat that is connected to the water heater can’t always be trusted. So, don’t just look at the readings – manually measure the temperature of the water that is coming from your tap and only then make the necessary changes.

  • The older gas water heaters have a special temperature knob near the base that you can use to adjust the temperature. Other heaters will have their control hidden behind a panel.
  • Make sure to turn off the power to the unit (gas heaters can still have some components that require electricity).
  • Adjust the temperature by turning the knob; test the water coming out of the tap. You might have to tweak the temperature a few times before you find the perfect one.

Hint: if your temperature controls have A, B, and C instead of numbers, then consult the manufacturer’s manual to find out what the letters mean. A is usually 120 F.

Read: Does HVAC Include Water Heater?

Hot Water Heater Settings Top and Bottom

A lot of electric heaters have two thermostats. And you would have to adjust both of them if you ever want to change the temperature of your water. 

The trick here is to adjust both thermostats the same amount. However, you should make sure that the top one is set to a temperature that is a bit higher

The top of the tank has hotter water in it, so setting the top thermostat to a higher temperature will help make sure that you’re using the heater more efficiently.

How to Check Your Tap Water Temperature?

You can easily check if the water is reaching the desired 120 F.

Hint: measure the temperature of the water that is coming from the faucet that is installed farthest from the water heater.

  1. If you have a water heater with a tank, try not to use the hot water for at least 2 hours before performing the test.
  2. After leaving the water to run for at least 3 minutes, measure its temperature with a thermometer (even a meat thermometer will do).
  3. If you are not satisfied with the temperature, adjust it on the thermostat and test the water again in 24 hours (if you have a tankless model, you wouldn’t have to wait for a full day). 

Read: What Is A Hybrid Water Heater?

The Top Reasons Why You Have No Hot Water

So, you have adjusted the temperature, but your water heater is failing to provide you with enough (or any) hot water?

Here is what might be wrong:

  • There is no gas supply or the breaker has tripped

If you have a gas water heater, then make sure that there is nothing wrong with your gas supply. If you have an electric unit, then you might be dealing with a tripped breaker.

  • A faulty high-temperature cutoff switch

In some cases, all you would have to do is find the switch and push the button. If you’re lucky, you will hear a click, and the water heater will get back to operating normally.

But if the power didn’t get restored, then you might have a faulty switch that would have to be replaced.

  • Faulty heating elements

In general, water heaters last for around 10 years. If it is getting close to the end of your unit’s lifespan, the heating element might start to fail.

By the way, this will happen a bit sooner, if you like to set the thermostat to an extremely high temperature.

  • A faulty thermostat

The thermostat is the device that tells your water heater when to heat up. If the device had gone bad, the unit won’t be able to provide you with hot water.

In a lot of cases, it is better to invite a professional to take care of this problem.

  • Water leaks

Your unit might be leaking water. Remember that extremely hot water can cause your tank to corrode and crack.

Read: How Many Amps Does Water Heater Use?

Why Is My Water Getting Warm but Not Hot?

This might be happening because your water heater is not able to provide your household with enough hot water. That’s why it’s incredibly important to get a heater of the right size that can fulfill all your hot water needs.

You should also know the recovery time of your unit. Once the heater gets drained, it is going to need some time to start making the water hot again.

A 70-gallon tank, for example, will take around 26 minutes to refill and heat the water.