My Water Heater is Getting too Hot

water heater headerWater that’s too hot isn’t an urban legend. It’s a situation that may lead to injury and higher electric bills as the water heater uses more energy to warm the water.

Here we’ll discuss five common reasons for the excessive hot water, why the thermostat needs to be set within a certain temperature range, and how to change the temperature on tankless and gas water heaters.

5 Reasons your water heater is getting too hot

A tank-style water heater can last up to 10 years with regular maintenance and repair, while tankless models can last up to 20 years. But, if your water heater has any of these issues, contact a plumber immediately to extend the functional lifespan.

1. Broken Thermostat

The first place to start is with the thermostat since it tells the water heater what temperature the water should be. When the thermostat breaks or malfunctions, the water heater continues to heat the water until you fix the issue.

water heater thermostatIt’s easy to test the thermostat to see if it’s working appropriately. Begin by lowering the set temperature 15 degrees to 20 degrees. Then, check the tap water temperature in two to three hours with a thermometer. If the water temperature doesn’t match what the thermostat was changed to, the thermostat is likely the issue.

2. Thermostat Isn’t Mounted Correctly

The thermostat needs to be mounted correctly and securely to the water heater tank to correctly track the water temperature. It can work loose over time from vibration and wear. If it appears to be off-kilter, use a screwdriver to loosen then realign properly before affixing it back in place.

3. Mineral Buildup

If you’re one of the 85% of Americans who live in a hard water region, you likely have mineral buildup inside the water heater tank. Hard water leaves behind calcium and magnesium deposits as the water heats. These deposits collect over time and interfere with appropriate heating of the water.


water heater part with mineral build up


One way to fight mineral buildup is with an annual plumbing maintenance, including flushing the water tank. This removes the mineral deposits, reducing overheating while helping the water heater operate efficiently and effectively for years.

4. Faulty Heater Element

Electric water heaters have one or two heating elements which, when working correctly, heat the water to the thermostat temperature. But when an element starts to ground, or die, it stays on all the time. Not only are you and others subjected to extremely hot water, but the continual heating also causes the element to burn out completely. Then you’re left with no hot water until the heater element is replaced.

5. Issues with the Pressure Relief Valve

The pressure relief valve helps release the steam created inside the water tank as the water heats. This also regulates the amount of pressure which would otherwise overheat the water. If the valve is blocked or malfunctioning, the water temperature only increases as the pressure rises and so does the risk of the water heater exploding.

pressure meme
You can check the pressure relief valve by pressing the switch on the side of the tank. If you hear a gurgling noise, it means the valve is releasing a small amount of pressure. If there’s no sound, or the valve makes a rattle or leaks a large amount of water, call a plumber immediately.

How to Change the Water Heater Thermostat

Your water heater temperature should be set between 120 degrees and 140 degrees Fahrenheit. If this sounds oddly specific, it is — it’s the range to avoid scalds and burns and to reduce any potential growth of Legionella and other illness-causing bacteria.

If this range doesn’t seem warm enough for your preferences, keep this in mind. At 150 degrees Fahrenheit, it only takes two seconds for adult skin to receive third-degree burns, the most severe type of burn.

Gas Water Heater

Older gas water heaters use a dial near the bottom of the tank to control the thermostat. Newer units have the thermostat neatly tucked away behind an access panel and layer of insulation for efficiency and protection.

  1. Turn off the water heater’s power source, generally from the circuit breaker.
  2. Find the thermostat access panel and use a flathead screwdriver to remove
  3. Peel back the layer of insulation over the thermostat.
  4. Your water heater may have one or two thermostats; if it has two, adjust the top thermostat to a higher temperature than the bottom one using the screwdriver.
  5. Tuck the insulation back over the thermostat and reattach the access panel.
  6. Turn the power back on at the circuit breaker.
  7. Relight the pilot light, if necessary.
  8. Wait three hours then test the water temperature from a tap. Adjust the temperature as necessary.

Tankless Water Heater

Most tankless water heaters use a digital thermostat panel to control the temperature. Locate the panel on your unit and adjust the temperature as needed.

tankless water heaterRegular plumbing maintenance is the best way to avoid extremely hot water coming from the tap and the many issues it can cause. Call Bell Bros today water heater needs.