Thereof, can you use PVC for water heater relief valve?
No. PVC pipe is not rated by the building code for use with hot water, so the installation shown above is wrong and unsafe. If the temperature and pressure relief (TPR) valve opens because the water heater is overheating, the water will be over 200º F.
Also, how do you fix a leaking T&P valve?
How long do T&P valves last?
As we mentioned earlier, pressure relief valves that are properly maintained can last for up to 30 years. In most cases, it’s important to look at the “why” behind pressure relief valve failure, rather than just replacing the valve in question.
Pressure Relief Valve – $20 to $200
If you notice that the valve is consistently leaking, it may mean that the tank’s pressure is too high, or you might simply have a faulty/clogged valve. The cost of a new pressure relief valve is about $20, and repairs may total to $200.
Is Your T & P Valve Leaking? If the t&p valve starts to leak, this means the water heater is not functioning normally. The most common cause of a temperature and pressure relief valve leaking is simply malfunction due to age. After years of use, the t&p valve can be too old to work properly.
Model codes require the T&P relief valve be set no higher than 150 psi. Therefore, a water heater with a MAWP of 160 psi still requires a T&P relief valve set at 150 psi, even though the vessel is designed and built to withstand a higher pressure.
Worn-out plastic – Some hot water tank drain valves are made of plastic. Over the years this plastic can become brittle, and when the valve is used to empty the drain tank, the plastic can crack, which can cause a leak. Failing gasket – Plastic drain valves also use a rubber gasket that deteriorates over time.
Causes of Excess Pressure in a Water Heater
Since water expands as it’s heated, higher-temperature water occupies more volume, which, in the confines of a water heater, results in increased pressure. If the pressure increases too much, your relief valve will activate, releasing water through the drain pipe.
Hot water systems
Water expands when heated, pressure builds up in the tank and is released through the overflow pipe. So water dripping or running from the valve can be a sign of a normal, functioning system. However, not all leaking overflow pipes are occurring due to normal pressure build up.
When an overflow pipe is dripping or running with water, one of the most common causes is a problem with a float valve. Float valves are found in toilet cisterns, cold water tanks and central heating feed and expansion tanks.