(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 6 of 6

Thread: water line issues between shower and hot water tank drain P-trap

  1. #1
    DIY Junior Member ns's Avatar
    Join Date
    Feb 2011
    Location
    Vancouver, BC
    Posts
    2

    Default water line issues between shower and hot water tank drain P-trap

    I have a hot water tank in a 'closet' next to the bathroom (all on the second floor). I had a leak fixed from the hot water tank drain pan where it attaches into the floor drain (water was leaking through to the ceiling on the first floor). There are two pipes discharging into the tank's floor pan drain: the tank's overflow pipe and a small copper water supply line coming from the wall. The plumber told me that little copper line is supposed to drip a little water into the floor drain/p-trap, but the problem is it gushes water whenever I turn the shower lever on. It doesn't happen when just the tub water is running.

    The plumber securing the little copper line so its pulled further down into the drain to prevent the water from splashing upwards into the drain pan. Will all that pressure of the water eventually cause leaking of the plastic/pvc(?) pipes down the line? Should I get the problem investigated and fixed (which would require opening up a few different walls including my bathtub surround) or can I leave it be?
    Last edited by ns; 03-01-2011 at 03:03 AM.

  2. #2
    In the Trades Gary Swart's Avatar
    Join Date
    Sep 2004
    Location
    Yakima WA
    Posts
    7,244

    Default

    What it sounds like to me is you have what we call a "closed" system and your Temperature/Pressure valve on the water heater is tripping due to water expansion created when the water heat is activated. A closed system is created when there is a check valve in the water supply line that prevents the expanded water from being absorbed by the water main. The check frequently is a Pressure Regulator Valve, but can be in the water meter itself. When water heats, it expands and if this expansion is not dealt with, the pressure in the water heat will rise rapidly and trip the T/P valve which is a safety device to prevent the heater from exploding. When the heating stops, the pressure returns to normal and the T/P closes. The cure for the problem is to install a thermal expansion tank in the cold water supply line between the PRV and water heater. This is an air-charged tank usually about 2 gallon size and this provides a place for the expanded water to reside until the pressure lowers. I think what you refer to a "the little copper line" is the pipe from the T/P valve. It does not, or at least is absolutely should not, connect solidly to the drain, so it does not pressurize the drain, and it should it never drip a water. By the way you describe your problem, it appears you are unfamiliar with plumbing basics, so I would urge you to hire a professional plumber to deal with this problem. It should not require opening walls, and if my diagnosis is correct, installing an expansion tank is quite simple. (It does have to be done correctly however)

  3. #3
    DIY Junior Member ns's Avatar
    Join Date
    Feb 2011
    Location
    Vancouver, BC
    Posts
    2

    Default

    Thanks for the reply! I've edited my post to hopefully be a little clearer.

    The plumber was already in and was the one who told me I'd end up having to open up walls to figure out the source of the problem. He'd already installed an expansion tank when trying to troubleshoot the source of the leak. I have both the tank's overflow pipe and that little copper water supply line discharging (not solidly fixed) into the drain pan floor drain.

  4. #4
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Location
    Cave Creek, Arizona
    Posts
    25,602

    Default

    The little pipe is from a "trap primer". It is a device to maintain the trap seal in the floor drain since you would not normally run any water into it. It IS designed to discharge water when a faucet is used. There are different models, some dribble a few drops of water when any faucet is used, some do it when a specific faucet is turned on, but still others, and yours may be one of those run a stream as long as the faucet is turned on. Whether there is even anything wrong with it is not apparent without knowing which kind you have. Normally, they are only defective when they run water continually. But, having said that, whoever piped the heater's safety valve into that pan did NOT do you any favors, because if it EVER operates the pan may overflow in a matter of seconds and flood the area.

  5. #5
    In the Trades Jerome2877's Avatar
    Join Date
    Aug 2009
    Location
    BC
    Posts
    384

    Default

    Pulling the pipe into the drain is not allowed as you are creating a cross contamination between the water supply and the sewer.

  6. #6
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    Location
    New England
    Posts
    21,374

    Default

    You could put a valve on that line and 'throttle' it back a bit, especially if the shower gets used frequently. A trap doesn't lose much water, and if you use the shower daily, a bit each time is all that is needed to keep the trap full. If a trap dries out, it provides an open connection to the sewer and you can get sewer gasses, files, etc. into the space. Keeping it full of water prevents that for the most part, so, that's why it has a trap primer there.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

Similar Threads

  1. New Water Tank Pressure Issues - looking for best and brightest.
    By jcdephi in forum Pumps and Tanks Well Forum & Blog
    Replies: 3
    Last Post: 08-29-2010, 06:16 PM
  2. Water Feed Line For Fish Tank.
    By nfored in forum Plumbing Forum, Professional & DIY Advice, Tips & Tricks
    Replies: 11
    Last Post: 12-01-2009, 06:41 AM
  3. Shower Drain Waste Line P-Trap Question
    By wescotthouse in forum Shower & bathtub Forum & Blog
    Replies: 2
    Last Post: 07-12-2009, 11:52 AM
  4. Tank water heater- dielectric union? heat trap?
    By edwardh3 in forum Plumbing Forum, Professional & DIY Advice, Tips & Tricks
    Replies: 2
    Last Post: 11-24-2008, 12:59 AM
  5. Removing water from P trap/drain
    By moobiker in forum Plumbing Forum, Professional & DIY Advice, Tips & Tricks
    Replies: 5
    Last Post: 08-14-2006, 05:16 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •