Why Does My Water Heater Keep Turning Off?

Few things test your patience like a water heater that refuses to stay on. If you find yourself constantly relighting the pilot or resetting the circuit breaker just to get a warm shower, there is an underlying issue that needs to be addressed. A water heater that keeps turning off isn't just annoying; it can be a sign of a failing component or a potential safety hazard.

Gas Water Heaters: Why the Pilot Light Goes Out

If you own a gas water heater, the primary reason it turns off is that the pilot light won't stay lit. Here are the most common culprits:

1. A Dirty or Faulty Thermocouple

The thermocouple is a small metal sensor situated near the pilot flame. Its job is to detect the heat of the flame and keep the main gas valve open. If the pilot goes out, the thermocouple cools down, triggering the gas valve to shut off to prevent a dangerous gas leak. Over time, the thermocouple can get coated in soot and dirt, insulating it from the flame's heat. If cleaning it doesn't solve the problem, the thermocouple may be broken and will need a professional replacement.

2. Bad Gas Valve

If the thermocouple has been replaced but the heater still won't stay lit, the main gas control valve could be defective. Replacing a gas valve is complex and requires dealing with the main gas lines, so this is definitely a job for a licensed plumber.

3. Inadequate Airflow

Gas water heaters need oxygen to maintain a flame. If your heater is in a small, enclosed closet without proper ventilation, it may consume all the available oxygen and suffocate the flame. Ensure there is adequate airflow around the base of the heater.

Electric Water Heaters: Tripping Breakers and Reset Buttons

If you have an electric water heater, it doesn't have a pilot light. Instead, if it keeps turning off, it usually means the unit is tripping your home's circuit breaker or the internal high-limit reset button.

1. The High-Limit Switch is Tripping

Electric water heaters have a safety device called a high-limit switch, usually located on the upper thermostat. If the water inside the tank gets too hot (typically above 170°F), this switch trips to cut the power and prevent scalding or excessive pressure buildup. If you have to keep pressing the red reset button on the side of the tank, you likely have a faulty thermostat that is failing to turn off the heating elements at the correct temperature.

2. Burnt Out Heating Elements

If a heating element splits or burns out, it can expose the internal wiring to the water inside the tank. This causes a direct short circuit, which will immediately trip the circuit breaker in your electrical panel. Continuing to flip the breaker back on is dangerous and won't fix the electric water heater issue.

When to Call a Professional

While you can visually inspect your water heater and perhaps clear away dust from the bottom air intakes, most issues that cause a water heater to repeatedly turn off require professional diagnosis. Playing with gas lines or high-voltage electrical components is hazardous.