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Bob the Plumber Replace Replace a Pressure Relief Valve (PRV)


What is a PRV and where is it?

   

How To Replace a Pressure Relief Valve (PRV) on a Hot Water Tank:

Step #1: Go to your hardware store and buy a PRV which is set for 150 psi. It will be the same whether you have a gas or electric hot water tank. Also, buy a roll of Teflon tape.

Step #2: No matter whether you have gas of electric, you do not need to drain you tank. Just shut-off the cold water valve that feeds the tank. For safety, turn off the gas, or electric to your tank.

Step #3: Okay here's the tricky part: Unscrew the overflow pipe that's connected to the relief valve. If the pipe isn't straight---or doesn't go directly outside--such that you can actually see it, you may have to cut the pipe and re-solder it, if it's copper. Or hopefully, the plumber installed a "union" in the pipe below the PRV and you will disconnect the union first, then unscrew the pipe that goes to the PRV.

Step #4: Unscrew the old relief valve. Wrap Teflon tape around the male threads of the new PRV. Go clockwise as your are wrapping and go around 5 times. Install the PRV in the tank. Tighten it as hard as you can leaving the discharge opening facing the existing overflow pipe. Connect the overflow pipe to the PVR, also using Teflon tape on the male threads of the pipe.

Once again, the tricky part is re-connecting the discharge pipe (overflow.)

Step #5: Turn on the cold water valve to the tank "Slowly." Then, turn the
gas or electric back on.

That's it...You're done!

If it looks too hard, call a plumber. It can be tricky hooking up that overflow pipe.

 

 

What is a PRV and where is it?

The PRV is a valve on the hot water tank that allows excess pressure to escape out of the hot water tank so the tank doesn't explode. It is located either on the top or on the side of the tank. It's an angle valve with a trip lever on top.
              

See a picture of the PRV and Discharge pipe


 It should have an overflow pipe (also called "discharge or blow-down pipe") which goes to the outside of the building or into a drip pan which is under and surrounding the hot water tank.
              

See a picture of the Discharge pipe and drip pan

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