Atwood HWH question

[marjoa]

1) Is there usually any problem removing a high pressure relief valve on a Atwood HWH?
2) To reinstall a high pressure relief valve, do you normally apply any pipe dope, teflon tape or anything like that to the threads?

[jelag]

I would never use teflon for the fear of a piece getting into the fluid system and lodging someplace you wouldn't want it....

I've used never seize, pipe dope, liquid teflon, to ease the threading of pipe threads.... if its a true pipe thread than it needs the lubrication to allow the ease of the threads to come together and hold... remember they are an interference fit...

[dons2346]

I used teflon tape. I start the tape one thread in from the end and put 2-3 turns on. Never had a leak

[Old-Biscuit]

Atwood uses a 3/4" NPT short probe T&P Relief Valve

Can be stubborn to remove old........best to remove exhaust shield to left of valve for easier access with wrench (better grip and working room)

Teflon tape, anti-seize, pipe dope...all acceptable. Just use sparingly....no need to go hog wild.

And sometimes it helps to 'tighten' a little bit BEFORE loosening ....helps break any scaling/corrosion on threads

[POPPASMURF]

As a 40 year plumber yes you "properly" apply thread sealant to the threads. You leave the first two threads untouched and apply thread sealant from there to likely depth of thread penetration. With those water heaters, I hope also to reduce electrolysis with the dis-similar metals (brass TP valve to Al tank)

[Gary RVRoamer]

Remember, though, the Atwood is an aluminum wall tank, so be very careful & gentle with that PT valve, both old and new. It's quite possible to distort the tank sidewall or mess up the threads.

[tim.kyfl]

My Atwood was a 1/2" thread, short hootie whatsis thing. Don't ask me how I know.

[marjoa]

Originally Posted by Old-Biscuit

Atwood uses a 3/4" NPT short probe T&P Relief Valve

Can be stubborn to remove old........best to remove exhaust shield to left of valve for easier access with wrench (better grip and working room)

Teflon tape, anti-seize, pipe dope...all acceptable. Just use sparingly....no need to go hog wild.

And sometimes it helps to 'tighten' a little bit BEFORE loosening ....helps break any scaling/corrosion on threads

Thanks for the advice on removing the exhaust shield. Today, I totally serviced the HWH today with 3.5gal. of white vinegar & the rest water, and cycled it 4 times. I chose to remove to the pressure relief valve to put the vinegar in and also serviced the valve by soaking it in vinegar, brushing it and then blowing it out with compressed air while I was at it. With the exhaust shield removed, I could get a pipe wrench on it and it came right out. I applied a little pipe sealant on both the valve and the nylon plug when I reattached. All set now for another year. Thank again everyone for your tips.

[Old-Biscuit]

Originally Posted by tim.kyfl

My Atwood was a 1/2" thread, short hootie whatsis thing. Don't ask me how I know.

Yours is a 1/2" NPT with short probe because that is what Atwood used thru 2003.

2004 model years and newer now use 3/4" NPT T&P Relief

Same thing with drain plug.....changed head size (drain is still 1/2" NPT)
Old was a 7/8"
New is 15/16"