Leaks only when hot water tank is on - fatigued joint?

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by dougonbay, Jun 9, 2011.

  1. dougonbay

    dougonbay New Member

    Messages:
    7
    Location:
    Saratoga Springs, NY
    Was wondering if anyone has seen this before. Just opened the cabin for summer - we blow out all the water lines when winterizing. Primed the pump, opened all faucets and slowly opened the main feed. The hot water tanked filled and all air was released from the lines. Everything was fine and there were no leaks.

    Then I turned on power to the hot water tank and there was a leak in a pipe underneath the floor. Just to be sure what was happening I shut the main water supply and power to the hot water tank and let the water tank cool for a day. I repeated the process (without power to the water tank) and all cold and hot lines worked fine with no leaks. Then I applied power to the hot water tank and sure enough the leak started again.

    My thinking is that there is a weak point somewhere that expands when the hot water hits it. Seems odd though. This weekend I have to remove the shower stall and cut the floor boards to get to the problem. Any insight would be helpful and ways we can prevent this from happening again. Thanks!

    Doug
  2. johnjh2o1

    johnjh2o1 Plumbing Contractor for 49 years

    Messages:
    1,143
    Location:
    South*East
    Are you sure it's not the T&P valve opening do to the tank over heating?

    John
  3. dougonbay

    dougonbay New Member

    Messages:
    7
    Location:
    Saratoga Springs, NY
    John, I'm not sure. This happens within 10-20 minutes after power is applied.
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,948
    Location:
    New England
    Most well/pump situations won't be affected by this, but it's possible that as the water expands when being heated, the pressure would rise. Again, this normally isn't an issue with a well/pump because the storage tank's bladder absorbs any expansion, but if there was a valve closed, or some weird configuration, it could be from expansion. It could also be that the tank is on its last days, and is leaking when it gets heated. Or, all that well water that could be quite cold has caused condensation, and it takes a bit of time for it to accumulate as it runs down pipes before you notice it and may have nothing directly related to do with the WH at all.
  5. dougonbay

    dougonbay New Member

    Messages:
    7
    Location:
    Saratoga Springs, NY
    Thanks for the feedback. I'm picking up a new T&P in the morning and head up to see if that's the problem. Shame on me for not doing that before posting!!!!

    Doug
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,948
    Location:
    New England
    A T&P valve is only supposed to release water under three conditions: you open it manually, the water temp exceeds the setting, or the pressure exceeds the setting. If it is defective or worn, or messed up in any other way, they often leak if you open it manually from then on as the mineral deposits, or seals, just can't handle the now messed up, pitted, or full of mineral deposits, and won't reseal completely.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,537
    Location:
    Cave Creek, Arizona
    The question is "How do you know there is a leak?" Can you feel it, see it, or hear it, and is the floor a concrete slab or wood over a crawl space. A "relief valve" line would not normally terminate "under the floor" unless it was into a crawl space and someone ran it the "quick and dirty" way.
  8. dougonbay

    dougonbay New Member

    Messages:
    7
    Location:
    Saratoga Springs, NY
    Success!! Replaced the T&P valve and all is well - it was leaking after 9 minutes with the old valve and with the new valve no leaks after 5 hours. Thank you so much for all of your input and advice!

    Regards,
    Doug
Similar Threads: Leaks water
Forum Title Date
Plumbing Forum, Professional & DIY Advice, Tips & Newbie Installing Water Filter -- Small Leaks Driving Me Crazy! Jul 9, 2013
Plumbing Forum, Professional & DIY Advice, Tips & repipe hous and now hot water heater leaks Nov 15, 2011
Plumbing Forum, Professional & DIY Advice, Tips & Dryer Vent pipe leaks water on the floor. Oct 14, 2010
Plumbing Forum, Professional & DIY Advice, Tips & Hot Water Dispenser Leaks Mar 15, 2010
Plumbing Forum, Professional & DIY Advice, Tips & Tank leaks at water connection only when flushed Dec 4, 2009

Share This Page