Water Heater Not Heating After Replacing Elements and Thermostat: Understanding the Causes

Most homeowners are confused when their water heater not heating after replacing the elements and thermostats. Don’t fret just yet. There are some logical explanations and reasons why such an issue happens.

Before you call a professional technician, understanding the basic reasons and how to deal with your device would be a good idea.

Reasons for Water Heater Refuses to Turn on

So, what are the possible reasons for the water heater not heating after replacing the elements and thermostat? Here are some of the possible causes.

water heater not heating after replacing elements and thermostat

  • Incorrect wiring or installation. Check whether the heating elements and thermostats were installed correctly and the wiring is connected properly. Miswiring or loose connections can prevent the heating elements from functioning.
  • Blown fuse or tripped circuit breaker. Check whether the fuse or circuit breaker is connected to the water heater to ensure they are not tripped or blown. Reset the breaker or replace the fuse if necessary.
  • Improperly sized thermostat or element. Ensure you installed your water heater’s correct wattage heating elements and thermostats. Using elements or thermostats with the wrong specifications can result in inadequate heating.
  • Trapped air or air pockets. After maintenance, air pockets can sometimes form in the water heater, preventing proper water flow over the heating elements. Try bleeding the air out of the system by opening a hot water faucet.
  • Faulty thermostats. Although they may be new, the thermostats could be defective. Test the thermostats with a multimeter to ensure they function correctly and provide the appropriate signals to the heating elements.

What Causes a Water Heater Thermostat to Burn Up?

Several reasons can cause the thermostat to burn up or malfunction. They are:

  • Electrical surges or overload. Power spikes, electrical surges, or overloading of the electrical circuit connected to the water heater can damage the thermostat. Sudden increases in electrical current can cause overheating and failure of electrical components, including the thermostat.
  • Age and wear. Like everything (especially related to components), thermostats have a limited lifespan. Over time, the electrical contacts and internal mechanisms can degrade due to normal wear and tear, eventually leading to failure.
  • Incorrect voltage or high voltage. If the voltage supplied to the water heater is consistently higher than the thermostat is designed for, it can cause overheating and damage to the thermostat and other electrical components.
  • Faulty connections or wiring. Loose connections, poorly done wiring, or frayed wires can create excessive resistance or short circuits, leading to overheating of the thermostat and subsequent failure.
  • Moisture or corrosion. Water heaters are sensitive to moisture and corrosion, especially in humid environments or in cases of water leaks. Corrosion or moisture damage can affect the thermostat’s functionality and cause it to fail.
  • Sediment buildup. Such a thing can cause the heating element to overheat. This excessive heat can affect the thermostat’s operation and lead to failure.
  • Manufacturing defects. In some cases, such a thing can cause premature failure. This is relatively rare but can happen.
  • Excessive heat exposure. If the device is installed in an extremely hot environment or subjected to direct sunlight, excessive heat exposure can affect the thermostat’s performance and lead to failure.

Read also: How to Reset Electric Water Heater

Why Is My Hot Water Heater Not Working After Replacement?

Some of the reasons are:

  • Thermostat settings.
  • Air within the water lines
  • Faulty heating element (applicable for electric heater)
  • Pressure relief valve
  • Gas supply issue (applicable for gas heater)
  • Defective gas control valve or thermostat.

Read also: Hot Water Heater Beeping: The Reasons and Solutions


If you have doubts about handling your heater, it’s always a good idea to reach out to a professional service. At least they can determine the reason why your water heater not heating after replacing the elements and thermostat properly.

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Jhon Thermon is a skilled author and water heater expert with years of experience in the field. He has authored several articles and books on various aspects of water heater installation, maintenance, and repair.