Why Does My Water Heater Keep Tripping the Reset Button?

So your water heater’s reset button is repeatedly tripping.

And after the 3rd trip to the closet or basement, you decide it’s time to figure out what the problem is.

Your water heater reset button, also called a “high limit safety thermostat”, is most likely tripping because the temperature of the water inside is too hot.

A continually tripping reset button can be caused by one of 7 things:

  • Your thermostats aren’t insulated
  • Hot water is “stacking” at the top of the tank
  • Faulty thermostats
  • A shorted element
  • Sediment build up
  • Loose wiring
  • A bad reset button

However, only the first two issues can be fixed without help from a professional plumber.

Let’s start by troubleshooting for the 2 issues that you can solve yourself.

Issue #1: Your water heater thermostats aren’t insulated

A water heater has two thermostats.

And each thermostat controls a heating element inside the tank. These elements are what actually heat the water. 


Anatomy of an electric water heater’s thermostats and heating elements.
Photo source: youdontneedamantofixit.com

The thermostats sit against the outside of the tank and measure the temperature of the water. Once the temperature of the water hits the pre-set maximum temperature, it sends a signal to shut off the heating element.

But if your thermostats aren’t insulated, they can get confused by the cool temperature of the room and read the water temperature as cooler than it really is. 

If this happens, the heating element doesn’t shut off when it should and continuously heats the water to dangerously high temperatures until the reset button trips.

What to do: First, locate your hot water heater’s thermostats.

You’ll most likely need to unscrew the access cover with a phillips head screwdriver first (shown below).


Photo source: Youtube-Water Heater Upper Thermostat Replacement

Once the access cover is removed, check for thick insulation like the picture below. 


Photo source: Youtube-Water Heater Upper Thermostat Replacement

If there is no insulation, this is most likely what is causing your reset button to trip.

If you’re now faced with the task of insulating your thermostat, we suggest you go ahead and insulate the entire water heater.

Why?

According to the United States Department of Energy, insulating your water heater can reduce your heat losses by up to 45%, which saves you anywhere from 4 to 9% in heating costs each year.

The good news is that insulating your water heater can be done on your own and usually only costs about $30.

Up for this money-saving challenge? Here’s a step-by-step video on how to insulate your water heater.

Issue #2: The upper heating element is “stacking” hot water

“Stacking” is when the water at the top of the tank gets hotter and hotter.

This happens when small amounts of hot water are used repeatedly within a very short time frame.

Example: Your in-laws are in town, and it’s dinner time.

You have a small amount of dirty dishes and you hand wash them quickly before you start cooking.

Two minutes later, your father-in-law washes his hands in the bathroom.

A couple minutes later, your mother-in-law uses hot water to rinse off and peel some potatoes for dinner.

After each incident, hot water is drawn from your water heater. And each time water is drawn from the tank, your dip tube quickly delivers cold water to refill the tank.


Photo source: Waterheatertimer.org

As that cold water enters the tank, the lower thermostat senses the drop in temperature and turns on the heating element to heat the water. Eventually that hot water rises to the top (because heat rises, remember?).

If that process happens repeatedly within a short timeframe, the hot water at the top of the tank quickly reaches dangerous temperatures that will cause your reset button to trip.

What to do: In most cases, stacking can be prevented by watching your hot water usage habits.

Be aware when hot water is repeatedly being used in short bursts and schedule your hot water tasks accordingly.

Issues that require a professional plumber

If your 2 thermostats are already well insulated and stacking isn’t your problem, you’ll need a professional plumber to diagnose and fix your issue.

Warning: A hot water heater uses 240 volts of electricity. If you’re unfamiliar with how a water heater works, do NOT attempt to fix anything on your own. 

Other issues that could be causing your hot water heater reset button to trip include:

  • Faulty thermostats. If one of your 2 thermostats is weak or broken and needs to be replaced, it won’t shut off power to the heating element. That element will continue to heat the water until it surpasses the maximum temperature and trips the reset button.
  • Heating element is “shorted”. An element that is shortened is usually damaged and sends an electrical current up the tank. A shorted element will continue to heat the water until the reset button trips.
  • Sediment build up. It’s common for sediment to collect at the bottom of water heaters. If sediment builds on or covers the lower element, it can cause the water to overheat and trip the reset button. If your water heater is making popping sounds, this is a sign that sediment is building inside and you’ll want a plumber to flush your tank. You may also need to replace the lower element.
  • Loose wiring. A loose wire can trip the reset button by confusing it. The reset button may sense the additional heat produced by the loose wire and trip.
  • Bad reset button. If none of the above are problems, there’s a good chance that the reset button itself may be damaged and need to be replaced.

Need a Minnesota/western Wisconsin Plumber?

If you live in Minnesota or western Wisconsin, our plumbers can diagnose the issue and repair your water heater quickly. Schedule your appointment with us today.

We serve Hastings, Apple Valley, Burnsville, Cottage Grove, Eagan, Woodbury, Lakeville, Rosemount, Stillwater, the southern metro area and more with quality electrical service.


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