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water heater popoff valve? Answered

I am trying to replace a popoff valve on my gas water heater, the heater is about 10 yrs old and is leaking at the plastic valve on the top where the water supply comes in. I have found a replacement but not sure how to get the old off and the new on?



7 years ago

Burf said it better then I ever read and Vyger points to the very real danger
associated with water heaters.

I HATE ! ! plumbing because most  DIY with pipes and threads has
always leaked on me ( even using Teflon tape ).

So, I'm warning you that after 10 yrs that corrosion on the threads could crack the water jacket and will certainly would stress my ability to install
a new popoff valve in a corroded thread without a leak.



7 years ago

That's actually called a 'pressure relief valve' or PRV and one that is 10 years old can be a real bear to remove. The exposed threads inside the water heater are probably corroded and caked with calcium deposits. About the only way to get one out is to muscle it out.
Before trying to remove the valve, be certain the heater is OFF and had sufficient time to cool to near room temperature. Shut off the water supply and disconnect the electrical or turn off the gas at the external gas valve. With a top mounted valve, you don't necessarily have to empty the tank but I would recommend you drain off several gallons of water first.
Get a large pipe wrench and clamp onto the flats on the valve and start turning counter-clockwise to loosen it. It may help to spray WD40 around the threads before trying to loosen it, and it may not. When you are trying to unscrew the valve, take care not to tip the tank over, because you will be pulling with quite a bit of force initially.


Answer 7 years ago

Yep. +1 , and big pipe wrench is the main tool. You might even need to add a cheater ( a length of old pipe slipped down over the handle to give you a few more feet of handle and leverage). You might also have to get a helper to try and hold the tank in place while you supply the torque. They almost always do break loose but it takes a lot of force to do it. When you replace it use pipe thread compound or anti seize compound on the threads to make the next time easier.

Just for the education you might want to watch the Mythbusters episode about water heaters and the damage they can do if the pressure relief is not installed correctly. They built a mock up of a 2 story house and with the relief sealed and the thermostat removed on an electric water heater it went through both floors, the roof and continued for 100 feet more into the air. So, its an easy do it yourself, just make certain you get it correct.


7 years ago

Rusted bolts very often become MUCH easier to remove if you heat them up with a propane torch. Keep in mind that metal expands when heated, so you want to heat the metal surrounding the bolt so it expands, not so much the bolt. If you heat the bolt (or valve in your case), then the metal will expand and make it TIGHTER. It also might help if you place a wrench on it and hammer on the wrench to get it started turning.

Jack A Lopez

7 years ago

The connections to every water heater I have been threaded pipe fittings.  They are installed/removed, tightened/loosened using wrenches.  

Whenever I do connections like these I put about ten layers of that teflon(PTFE) tape on the fitting, and this prevents it from leaking when tightened.  

For water heaters, it helps if sections of the cold-in and hot-out pipes are flexible.  That way everything does not have to line up perfectly the way it would if all the pipes were perfectly rigid. 

Also it looks like there are lots of good 'ibles in the "Related" panel on the right there. --------->
Including a YouTube channel that looks promising.