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Thread: Stuck Water Heater Drain Valve

  1. #1

    Default Stuck Water Heater Drain Valve

    Crawling under the house to deal with the well pump has led me to take a look at the water heater. I was going to drain it because I doubt the previous owners of the house ever did. However, the plastic valve is stuck closed! I'm afraid to wail on it for fear of breaking it. Would spraying inside the spigot with WD40 help or would that just eat away the plastic? Any suggestions? Note that the valve is probably stuck closed by iron and mineral deposits--in fact I can see that dreaded orange tinge on the ball valve inside the spigot.

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    New England


    It'll probably break. WD-40 probably won't help. I'd think about shutting the WH off, letting it cool, and then just try to unscrew the whole valve and replace with a decent one. While you have it off, if it doesn't drain (may not much sort of like a straw with your finger over the top (assuming you close the inlet supply), you could take something and poke through the crud to help loosen it and let it drain. Depending on how old it is, it might either help, or speed its life or death.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3


    Quote Originally Posted by jadnashua View Post
    Depending on how old it is, it might either help, or speed its life or death.
    Ah yes, the old "don't fix it if it ain't broke". That's precisely what I was thinking too. Perhaps it's best that all the sludge stays where it is rather than flowing to things like my new $600 washing machine! Water heaters are cheaper....

  4. #4

    Default If it Ain't Broke

    Saw episode of This Old House where new owners had plumber drain 10 year old heater that had probably never been drained. Lots of crude (mineral deposits) came out. Two months later it started leaking from crack and had to be replaced. Funny thing was plumber said that typically his experience was that every time he drained/flushed an old heater that hadn't been periodically drained, the unit would usually fail within a few months.

    Wonder if getting all that crude out exposes area of liner that has been compromised by being buried in crude.

    Curious if you pros have had similar experiences??????

  5. #5
    Master Plumber Redwood's Avatar
    Join Date
    Dec 2007


    I would consider a water heater that old not to be worthy of being worked on in the beginning.

  6. #6


    Quote Originally Posted by Redwood View Post
    I would consider a water heater that old not to be worthy of being worked on in the beginning.
    Agreed (or rather, I'd agree to anything which keeps me from having to crawl under the house again).

    However, when I bought my previous house, the inspector guesstimated the water heater was about 8 years old. Never had a bit of problem with it in the SIXTEEN more years that I lived there with it. Never tried to drain it either. It was an A. O. Smith brand, if that makes any difference.

  7. #7
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Cave Creek, Arizona

    Default heaters

    Any reputable plumber or inspector could tell you EXACTLY how old the heater was to the month it was construted. A plastic drain valve will almost definitely snap off, but then replacing it is usually a simple job.

  8. #8
    Master plumber Jay Mpls's Avatar
    Join Date
    Sep 2008


    they never snap off when I'm in a position where it doesn't matter!
    A crawl space?! *snap* just by gazing at it.


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