Water Heater Pressure Relief Valve Pipe Size

Unscrew the overflow pipe from the tpr valve using a large adjustable wrench.

Water heater pressure relief valve pipe size.

The tpr valve will activate if either water temperature measured in degrees fahrenheit or pressure measured in pounds per square inch psi exceed safe levels. A trapped tpr dischage pipe is a common defect when a replacement water heater s tpr valve is lower than the original one and the installer connects to the exisitng discharge piping at the wall. Most residential water heaters have a 3 4 threaded opening for the discharge pipe. The first thing to do is to look at the relief valve sizing chart for hayward relief valves.

The pipe itself needs to be either copper cpvc or galvanized water piping. Model codes require the t p relief valve be set no higher than 150 psi. The relief valve on your water heater has a pipe attached. The valve should be connected to a discharge pipe also called a drain line that runs down the length of the water heater tank.

Take the old valve to the hardware store and buy a replacement valve that matches it. The discharge pipe shall terminate within 6 inches over the floor and not have any threads on the end nor are there to be any valves in it. By code you have to run the same size as the opening which means the pipe needs to be 3 4 in diameter. It will permit a flow of only 13 gpm 7 gpm less than.

Not terminate more than 6 inches 152 mm above the floor or waste receptor. Be constructed of those materials listed in section p2905 5 or materials tested rated and approved for such use in accordance with asme a112 4 1. These valves may look identical but they re set to go off at 30 psi. This size valve will not work.

If a pressure relief valve for a boiler is accidentally installed on a water heater it will leak like crazy from the start. Tpr valve shall extend into the heater tank and monitor the temperature in the top 6 inches of the heater. Another factor in determining the pressure rating of the t p relief valve is the code itself. It s important to choose a replacement valve with the same btu rating and pipe size.

From the chart we can see that a 3 4 valve set at 40 psi the required system pressure will flow 13 gpm at 10 psi overpressure the set pressure of 40 minus the pressure output of the pump of 50 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. There are several styles of tpr valve available including universal pressure relief valves. Not have a threaded connection at the end of the piping.