Thermal Relief Valve Always Dripping? Here’s What to Do

July 3, 2024
Hot water tank with thermal relief valve.

Wondering what to do if the thermal relief valve on your hot water tank keeps dripping? First, make sure you know how to identify it and what it means.


What Does it Look Like?

The thermal relief valve is a valve located on the side of your hot water tank, near the top. It may have a copper or plastic tube attached to it that runs down to the floor, allowing water to flow out near the drain in your floor. If you notice water collecting underneath your hot water tank, check to see if it’s coming out of your thermal relief valve tube. 


Is There Something Wrong with My Hot Water Tank?

If your thermal relief valve keeps opening and dripping water, a likely cause is an expansion issue with your hot water tank. As water in the tank heats up, it expands. If hot water is not being used in your house at that moment, the hot water in the tank has nowhere to go and so it tries to make its way back into the cold water supply line, which causes pressure inside the tank. The thermal relief valve’s job is to open when this happens in order to relieve the pressure and give the water somewhere to go.

The Benefits of a Potable Expansion Tank vs Thermal Relief Valves

If your thermal relief valve is stuck open and has failed, you can fix the problem by having a potable expansion tank installed and removing the thermal expansion valve or capping it off. An expansion tank is a small tank attached to the cold water supply line at the top of your hot water tank. The expansion tank works as a place for excess hot water to move to when the pressure in the tank is too much, which means that your relief valve will not have to open as often in order to reduce pressure. Thermal relief valves have been proven to be unreliable and in our opinion a potable expansion tank is a better option.

Interested in upgrading to an expansion tank or need your hot water tank inspected? Trust John Sadler Plumbing & Heating to get the job done right.

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