Pressure Relief Valve Spewing Water - 4 Ways to Stop It
A pressure relief valve is an essential safety component found on most residential water heaters. It is designed to automatically open and release water if the temperature or pressure levels in the tank get too high. By doing this, it prevents explosion hazards and protects the water heater from damage.
While limited water discharge from the pressure relief valve is expected from time to time, a valve that spews water continuously signals a definite problem needing attention. Ignoring a leaky valve can lead to property damage, mold growth, utility bill hikes, and even tank failure down the road.
What is a Pressure Relief Valve and What Does it Do?
A pressure relief valve, sometimes referred to as a T&P (temperature and pressure) valve, is usually located near the top of the water heater tank. When functioning properly, it will only open to release hot water if the pressure or temperature exceeds safe thresholds that could potentially damage the tank and related components.
Definition and purpose of a pressure relief valve on a water heater
A pressure relief valve is specifically designed to release water if the pressure levels within the water heater system climb too high. It serves as an important safety release mechanism that ultimately protects the tank, heating elements, supply lines, and other components from damage due to excess internal pressure buildup.
When should the pressure relief valve open?
Ideally, the pressure relief valve should only open and release water if the pressure climbs above the maximum limit set by the valve's pressure rating. This will most commonly occur if the tank or water heater system becomes significantly overpressurized for any number of reasons.
It also may occur during rapid water thermal expansion while the tank is heating up. As the water expands, additional pressure may momentarily build up faster than the expansion tank can handle, requiring the relief valve to open briefly to alleviate the excess pressure spike.
4 Common Reasons a Pressure Relief Valve Leaks Water
If a pressure relief valve is spewing water continuously and frequently, one of the following common issues is likely the underlying cause:
1. Old, faulty, or defective valve
A pressure relief valve that does not seal tightly will allow water to leak through slowly. This commonly occurs as valves age over time and mineral deposits start to clog pathways or cause internal components to degrade and malfunction.
Physical damage, wear and tear, impurities in the water supply lines can also prevent the valve mechanism from fully closing as designed, resulting in small water leaks.
2. Clogged valve
While rare with periodic valve exercising, pressure relief valves can become clogged over many years of use. Debris consisting of sediment, minerals, rust particles and other water impurities can make their way into the valve and prevent the mechanism from sealing completely.
This leads to obstructed flow pathways and small leaks even when the tank pressure remains within a normal range. A clogged valve is one of the most common causes of water dripping or spewing from a relief valve.
3. Excessive pressure
If the water heating system experiences issues that spike water pressure like a failing heating element, dip tube damage, or a broken thermostat, the building pressure may climb to unsafe levels rapidly.
When this happens, the relief valve will open as intended to release the pressure down to safe levels. The forced leakage protects the tank and plumbing from pressure damage.
4. Supply line/pipe leaks
External leaks from water supply lines, hot or cold water pipes near the tank can sometimes cause water to channel through the relief valve, especially if valves are old and don't seal tightly.
When this happens, it may seem as if the relief valve itself has failed or is leaking even though the pressure in the system is normal.
How to Diagnose the Cause of a Leaky Pressure Relief Valve
Finding the root cause of a leaky pressure relief valve requires a systematic process of elimination guiding you to the source of the issue:
Inspect valve and supply lines thoroughly
Closely check the physical condition of the pressure relief valve and the supply lines around the tank for any signs of debris accumulation, damage, leaks or corrosion. See if the valve feels loose or if water stops dripping with the valve manually held closed.
Check water heater for proper operation
Make sure all water heater components like heating elements, thermostats and valves are functioning properly. Conduct tests to verify proper temperature regulation and measure water pressure levels when the tank is idle versus actively heating.