The relief valve is an important safety feature on most water heaters. Also known as a pressure relief valve, it’s designed to relieve excess pressure. Water heaters produce pressure as a byproduct of their operations. As they generate heat, the water will become warmer while simultaneously expanding. This thermal expansion creates pressure within the water heater. To relieve excess pressure, most water heaters are equipped with a relief valve.

When inspecting your water heater, you may notice that the relief valve is leaking. You may hear or see water dripping from it. The relief valve is typically connected to a discharge pipe or hose. Water will flow from your water heater to the discharge pipe or hose so that it can drain. What causes relief valves to leak exactly?

Overheating

Overheating may cause the relief valve to leak. It’s normal for relief valves to leak occasionally. After all, they are designed to relieve excess pressure – a process they perform by discharging some of the heated water out of the relief valve. But if your water heater is overheating, the relief valve may continue to leak.

Water heaters are designed to operate within a specific temperature range. Most modern water heaters, for instance, operate at a temperature of 90 to 120 degrees Fahrenheit. If your water heater exceeds this temperature, it will produce excess pressure that can manifest in the form of a leaking relief valve.

Stuck Open

The relief valve on your water heater may leak if it’s stuck open. Like most other valves, water heater relief valves can be open or closed. In the open position, water will flow out of the water heater and through the relief valve. In the closed position, water will remain trapped inside of the water heater.

Relief valves should change between an open and closed position automatically depending on the pressure to which they are exposed. Relief valves, though, can fail. If the relief valve on your water heater becomes stuck open, it will continue to leak.

Worn Seal

A leaking relief valve might be the result of a worn seal. The relief valve must feature a waterproof seal with your water heater and the discharge pipe or hose to which it’s connected. If the mating surface between any of these components has been compromised, the relief valve may leak.

If your water heater has a leaking relief valve, you should get it inspected by a professional. The leak may be a normal part of the relief valve’s operations, or it could be a sign of a more serious underlying problem.