Help me not be a butt(crack) of a DIY plumber...
May 5, 2012 2:59 PM   Subscribe

PLUMBING: Is it easily possible to replace what seems to be a leaky drain valve (slowly dripping) in a hot water heater tank? Is that what's pictured in my link? Is it even worth it when the top of the tank is corroded (although it seems to be coming from the pipe and not eating thru' the metal at all) like this? This thread says don't mess with it. And right, you know: T'anks for the help.

Bonus question worth one No Prize: Why is it that there seems to be no pressure relief valve on the H2O pipe that feeds the tank, nowhere to divert the water to a hose or a drain? Is that replaced by the lower valve I'm talking about?
posted by Shane to Home & Garden (10 answers total)
That thing sticking out on from the side in your picture #4, to the right of the whirlpool logo, should be the pressure relief valve.

Still, my first reaction to your water heater is that I would want it RIGHT THE FUCK OUT OF MY HOUSE YESTERDAY.
posted by ROU_Xenophobe at 3:11 PM on May 5, 2012

Time to replace the water heater, I'm afraid. That thing looks like a Mythbusters experiment waiting to happen.
posted by Thorzdad at 3:13 PM on May 5, 2012

Bonus answer: The TP valve is on the side of the hot water heater (you can see it on the right in your linked picture).

Main answer: is the drain valve leaking from inside (i.e., it keeps dripping out from the normal valve exit no matter how you've tightened it) or from around the valve? If it's leaking from within, just buy another inexpensive modern valve and screw it onto the end of the normal drain valve (with the usual thread sealant / plumber's tape).

Re: the corrosion, have you checked the sacrificial anode that screws into the top of the tank? (Shut off the water pressure, unscrew and inspect.) I'm willing to bet it has absolutely nothing left.
posted by introp at 3:43 PM on May 5, 2012

A valve on the pipe above would be a shutoff valve, not a pressure relief valve. Since there's no shutoff valve specifically for the tank, you'd need to shut off water for the whole house. Then you'd drain the tank by opening the valve that's leaking, after which I assume you could replace the valve washer and/or packing. I've never rebuilt a water heater drain valve, but it looks pretty basic.

I would not recommend simply screwing on another valve as introp just suggested; the threads on the existing valve are hose threads, not pipe threads.
posted by jon1270 at 3:54 PM on May 5, 2012

introp and ROU, you're right, and I feel stupid now but -- haha! [*groan*] -- plenty of things to distract me from the TP valve. Btw, there's 4'+ of copper pipe running from the release valve, and I'll be stripping that and any other copper off the tank before they pick it up, LOL. Of course I won't tell them that. That's what little good advice I can add to this discussion.

Thanks, introp, I'll do both of those things -- but I assumed, as with most valves, that overtightening would just do damage? ROU and Thorz -- thanks for the LOL.
posted by Shane at 3:55 PM on May 5, 2012

Thanks, jon1270... That's what I thought (replace valve/washer), but hate to do. Maybe I'll investigate the corrosion first (as said introp) so I don't fix a valve on something that's headed for looking like the remains of the Titanic.
posted by Shane at 4:25 PM on May 5, 2012

When you replace the heater, the T&P valve will likely be in the same place, so they'll be able to re-use the threaded fitting and 3/4" pipe connected to the current one. The money you'd make scrapping the current T&P pipe is far less than you'll spend if they have to make up a new one.
posted by notsnot at 4:26 PM on May 5, 2012 [1 favorite]

Definitely don't over-tighten; my comment on "no matter how" (notice I don't follow with "hard") is that sometimes an old drain valve leaking (not leaking from the stem) can be made to seal if you open it up, let some water flow out, then normally re-close. (Also, jon1270 is right in that they'll be hose threads, but you can buy valves for HT just as easily as for PT.)

Also, since this sounds like your first gas hot water heater experience: the sacrificial anode that's in the top is designed to be replaced regularly. So it having been eaten away isn't automatically Super Bad, it just means that the thing has been operating without one for some non-zero time, which just means it might be Super Bad.
posted by introp at 4:34 PM on May 5, 2012

I learned one thing worth adding to this thread: The next time you're going to throw out an old garden hose, save at least 10 or 12' of it with the female end attached. It works wonders when you have a leaky valve like this and you don't want continually to empty a bucket, or when you need to drain something entirely.
posted by Shane at 5:31 PM on May 6, 2012

Thanks, all. .
posted by Shane at 1:16 PM on May 13, 2012

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