Pressure relief valve removal

[motozen]

Our pressure relief valve needs replacing as it is encrusted with deposits. Snapping the valve open and closed does not clear the seal, so it's leaking.
The problem is that it appears that the threads where the valve screws in to the tank have deposits making removal difficult. I can get a long stem plumbing wrench (aka: knuckle saver) on the valve, but I am unable to get the valve to turn. I'm a bit paranoid about really torquing on it and damaging the heater.

Thoughts, advice???

[Tuco]

Use a heat gun to heat the fitting around the valve then try and remove it.

[motozen]

Thanks, I'll give it a try.

[Kevin245]

If the fitting is made of aluminum I'd advise against using an open flame heat source. Aluminum does not react well when heated with a soldering torch or similar tools. The slightest overheating and the material will literally melt away before you can blink an eye.

[alantbird]

triflow lubricant for a few days should do the trick

[motozen]

Thanks for all your ideas. WD, 10 minutes and a honking wrench did it. Destroyed the old one, but the heater is just fine.

Any ideas on what to do to prevent the buildup of calcium? And considering how the valve was encrusted, would running vinegar into the plumbing and letting it sit for a day help to remove any buildup in the lines and faucets?

[motozen]

I took the recently removed pressure relief valve from the H2O heater, which was completely encrusted in calcium, and soaked it for 24 hours in vinegar. I was amazed at how it dissolved almost 100% of the calcium. I tried to post pix, but it would not upload them, even after I shrunk them to the required file size?!?

Considering how it cleaned off almost all of the calcium buildup, I'm wondering if: 1) all of the water lines and valves have calcium buildup, and 2) if filling the system with vinegar and letting it sit for a day would clean it all up, or cause harm?

Thoughts/advice?

[Kent M]

1. Vinegar works.
2. Leaving it overnight (or for a full 24 hours) will harm nothing. Vinegar is acetic acid, which is only mild.

It works in home water heaters, as well.