Water Heater Pressure Relief Valve Pipe Size

Model codes require the t p relief valve be set no higher than 150 psi.

Water heater pressure relief valve pipe size.

8 termination of the tpr drain pipe cannot be more than 6 inches or less than two pipe diameters above the floor ground or waster receptor flood rim level. It s important to choose a replacement valve with the same btu rating and pipe size. By code you have to run the same size as the opening which means the pipe needs to be 3 4 in diameter. Not have a threaded connection at the end of the piping.

Take the old valve to the hardware store and buy a replacement valve that matches it. These valves may look identical but they re set to go off at 30 psi. Tpr valve shall extend into the heater tank and monitor the temperature in the top 6 inches of the heater. Most residential water heaters have a 3 4 threaded opening for the discharge pipe.

If a pressure relief valve for a boiler is accidentally installed on a water heater it will leak like crazy from the start. 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. Not terminate more than 6 inches 152 mm above the floor or waste receptor. The valve should be connected to a discharge pipe also called a drain line that runs down the length of the water heater tank.

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. Not have valves or tee fittings. Another factor in determining the pressure rating of the t p relief valve is the code itself. This size valve will not work.

The pipe itself needs to be either copper cpvc or galvanized water piping. It will permit a flow of only 13 gpm 7 gpm less than. 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. The first thing to do is to look at the relief valve sizing chart for hayward relief valves.

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. 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. Since in our example the pipe size is 3 4 let s start there and see if a 3 4 valve will be the best choice. The relief valve on your water heater has a pipe attached.