Replaced toilet, shower head - TPR leaking

Discussion in 'Water Heater Forum, Tanks' started by TomInNH, Jan 10, 2010.

  1. TomInNH

    TomInNH New Member

    Messages:
    4
    Location:
    NH
    Hi all - first post.

    I'm an IT guy, but can do some no-brainer type activities - changing toilet, shower heads, replacing faucets etc - nothing that requires touching gas or sweating any pipe.

    I removed an old toilet & shower head (doing some bathroom tiling & green board in my shower). It took me a few days to get the toilet in and in that time my TPR on my gas hot water heater started leaking. I have a bowl under it just in case, but it was filling it up in a 24-hour time span.
    The TPR valve was replaced in July 09, and had been fine until the toilet removal.

    I put the toilet in, but not the shower head & then read something, somewhere about 'if you haven't done any plumbing or renovation work, it's probably a bad TPR.' I temporarily put the shower head back in, ran hot water out of all my outlets - and it seems as if the dripping has lessened. Coincidence? Think it'll stop all together?

    Any thoughts would be appreciated! Thanks!
  2. SteveW

    SteveW DIY Senior Member

    Messages:
    1,052
    Location:
    Omaha, NE
    Could be thermal expansion

    Go and buy a $10 pressure gauge from a hardware store, and hook it up to your washing machine hose bib.

    Then see what your house water pressure is.

    Next, turn on your bathtub faucet to full hot for a couple minutes, to partially drain your water heater. Shut off the tub faucet, make sure no one in the house runs any water for a while, then immediately go and watch the pressure gauge. If it starts to rise under these circumstances, you have "thermal expansion" and need an expansion tank.

    I am guessing that your old toilet may have allowed this excess pressure to vent off from time to time so the TPR valve didn't leak - until you replaced the toilet.
  3. TomInNH

    TomInNH New Member

    Messages:
    4
    Location:
    NH
    Steve -
    Thanks for this, very helpful. Home Cheapo, here I come!
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,816
    Location:
    New England
    Water will leak at the weakest point. A toilet fill valve sometimes is that weakest point. If it gets high enough to trip the T&P valve, assuming it is working, you've exceeded 150#. Sounds like you need an expansion tank.
  5. Runs with bison

    Runs with bison New Member

    Messages:
    891
    Location:
    Midwest
    As has been mentioned, the old toilet fill valve was acting as relief. Mine did the same thing! When I replaced the last of the three toilets with new Totos my T&P valve started leaking. I had already been using a test gauge and knew that I had not exceeded 120 psig in previous spikes (this was also the main's supply pressure. So I put the gauge back on the hose bib to confirm. The T&P was popping as it should at about 150-155 psig indicated.

    It was just a trickle, but I didn't want to rely on it resealing so I installed a thermal expansion tank (not required by code here.) I was also concerned about the spikes being hard on the new fill valves and other devices, as well as the potential for a burst/leak if there were any weak lines/connections.
  6. TomInNH

    TomInNH New Member

    Messages:
    4
    Location:
    NH
    Thanks for the feedback!

    Now I have another question. Could I attach the pressure gauge to my outside water connection & turn it on, as if a hose was attached? It's literally 2 feet above the washing machine connection.
  7. Runs with bison

    Runs with bison New Member

    Messages:
    891
    Location:
    Midwest
    I hooked mine up outside like that...of course it wasn't subzero or even freezing at the time. Don't leave this hooked up during a freeze or you will burst something.
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,816
    Location:
    New England
    You can hook it up to the drain valve on the water heater or a washing machine hose connection, too. Or, buy adapters and attach it to nearly anything.
  9. TomInNH

    TomInNH New Member

    Messages:
    4
    Location:
    NH
    I contacted a plumber in the area & explained the situation.

    He said "you absolutely need a new hot water heater" and "the expansion tank will not help with the pressure, or issue causing the TPR to leak" and "for an extra $60 I'll add an expansion tank with a new hot water heater."

    He said that Murphy's law caused the leaking after the toilet was replaced.

    Thoughts? My hot water heater is getting older - is he correct about the expansion tank not being able to cut it? :confused:

    Thanks again guys.
  10. SteveW

    SteveW DIY Senior Member

    Messages:
    1,052
    Location:
    Omaha, NE
    Start with the basics.

    What is the baseline water pressure, and what does the pressure go up to when the water heater is heating that slug of water (after you draw off 5+ gallons at your tub as described above)?
  11. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,270
    Location:
    Cave Creek, Arizona
    heater

    AND WHAT will a new water heater do that the old one does not. When I hear fo plumbers like that my first recommendation is to find a better plumber. One that is more concerned about what your problem is, than how to make this month's truck payment, although most of the plumbers like that do not have trucks new enough to need payments.
  12. Runs with bison

    Runs with bison New Member

    Messages:
    891
    Location:
    Midwest
    Tom,

    It's not Murphy's law, it is removal of the weakest link (the toilet fill valve that leaked at some high threshold pressure...but below the T&P valve setting). Before I experienced the same thing I was puzzling over why I didn't seem to need a thermal expansion tank. I had no indication of leaks anywhere and I recognized the volume change in the water had to be taken up somewhere in the system. When I changed out the toilets the mystery of that "somewhere" was convincingly solved. :eek: Remember, unlike your case I had instrumented with a test gauge before and after the change so I knew what the pressure was doing before hand. In doing troubleshooting analysis the most important part is determining what changed and how it might effect the observed problem.

    I don't know whether the plumber is just trying to sell you a tank, is trying to be overly cautious, or just hasn't thought this through. Now, if you put a test gauge on it and show the T&P is relieving at a much lower pressure than it is set at things are different. But even in that case the first thing you would try is replacing that relief valve.

    If he hasn't put a gauge on it (and assuming you haven't and therefore haven't reported pressures to him yet) then there is no way he should be confident in calling the tank the problem.
  13. SteveW

    SteveW DIY Senior Member

    Messages:
    1,052
    Location:
    Omaha, NE


    So, Tom, any updates?
  14. Redwood

    Redwood Master Plumber

    Messages:
    7,453
    Location:
    Connecticut
    Yea, what does the new plumber say?
    I hope you took that advice
  15. Terry

    Terry Administrator Staff Member

    Messages:
    14,780
    Location:
    Bothell, Washington
    If replacing an old toilet caused the T&P to start leaking,
    you could assume that the old fill valve was leaking and letting off pressure.
    Fixing the leak, then you have a worn T&P leaking when the pressure rises.

    A simple pressure check with a gauge would let you know how much pressure you are dealing with.
    A T&P is set to release at 150 PSI
    The home should not have pressure higher then 80 PSI
    If the pressure is higher, you would be looking at a pressure reducer.
    If the T&P release water after the pressure has been set down to 80 or less, then you might be thinking worn T&P
    If pressure starts to build up higher and the T&P release water, then you have expansion issues.
    And expansion tank would help in that case.
  16. SteveW

    SteveW DIY Senior Member

    Messages:
    1,052
    Location:
    Omaha, NE
    Looks like we are all saying the same thing in slightly different ways.

    Now it would be nice for the original poster to come back and let us know if we are right!
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