Code for water heater T&P drain in a basement

Discussion in 'Plumbing Code Questions' started by ginahoy, Apr 21, 2018.

  1. ginahoy

    ginahoy Building Systems Engineer

    Joined:
    Dec 23, 2006
    Location:
    Sierra Vista, AZ
    I'm preparing to break ground on a my new home, which has a fully below-grade basement. A storage type water heater will be centrally located in the basement. There will be two interior sumps -- one with a sewage ejector pump for the bathroom fixtures and the other for the footer drain. I'm considering specifying a drain tile in the slab beside the water heater with a 'side arm' T&P drain pipe such that any release would flow directly into the drain tile and end up in the footer drain sump. Is this acceptable?

    Basements are a rarity around here (SE Arizona) so it wasn't surprising that the first plumbing contractor I met with expressed concern about my design. First, he said he didn't think water heaters are allowed in basements. Say what?! That seems like nonsense! Next, he said the T&P drain must be routed to the outside so any activation would be noticed. I think my design accomplishes that. My takeaway is that this guy had never seen a basement before. Time to move on to another contractor.

    Before I interview another plumbing sub, I want to find out if my T&P design could be a code violation. On the other hand, couldn't I simply route the T&P drain up through the floor trusses to the outside, thus saving the cost of installing a drain tile? No need for a pump since any release, by definition, would be under pressure, right?

    The building site is in a rural area. The county allows owner-builders to opt out of plan review and inspections, which I have done. Still, I'm supposed to follow code, and in any case, I don't want to ask a licensed contractor to do something that would be a code violation. Clearly I need to hire a quality plumber who understands basements. If I can find one.
     
    Last edited: Apr 21, 2018
  2. hj

    hj Master Plumber

    Joined:
    Aug 31, 2004
    Occupation:
    Plumber
    Location:
    Cave Creek, Arizona
    You CANNOT run the discharge line upwards. It HAS to drain to a lower elevation, even though it is under pressure. On to the floor or into a pump sump are about the only options if you want the heater in the basement.
     
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  4. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    "Drain tile"??? I hope you don't plan to use terra cotta drain tiles in your floor or for anything functional. Use pvc or abs according to what is common locally.

    How about calling it a floor drain? WH T+P runs to 6 inches above the floor. Floor drain below receives the water. The T+P drain is the only good use for galvanized pipe in a home IMO. Copper works too everywhere. CPVC would be allowed some places and not others.
     
  5. ginahoy

    ginahoy Building Systems Engineer

    Joined:
    Dec 23, 2006
    Location:
    Sierra Vista, AZ
    Sorry, by drain tile I was referring to a floor drain made of plastic with a 'strainer' plate. I never stopped to think about the origin of the term. Good to know there's no issue with my design. Thanks.
     
  6. crush62

    crush62 Journey Level Plumber/State Certified Plmbg Instr

    Joined:
    Jun 16, 2020
    Occupation:
    Journey Level Plumber/State Certified Plmbg Instr
    Location:
    Lynnwood, Wa.
    You may also put a secondary T & P on the water system,(where you can access it should it fail) and install it where you can get that drain to gravity. It would be rated at 125psi/210deg. Should you experience high temp/over pressure the 125psi would discharge first. Running the T & P into a condensate pump is out of the question,too much volume should the T & P discharge..
     
  7. Jeff H Young

    Jeff H Young In the Trades

    Joined:
    Feb 27, 2020
    Location:
    92346
    when we cant gravity drain the Tand P we put a pressure relief valve where it can gravity drain out in the piping above grade. and on the water heater in place of the tand p we install a watts 210 automatic gas shut off valve. of cource if you got a floor sink or drain dont need it
     
  8. hj

    hj Master Plumber

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    Aug 31, 2004
    Occupation:
    Plumber
    Location:
    Cave Creek, Arizona
    A TEMPERATURE relief valve remote from the heater would be completely USELESS.
     
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  9. Terry

    Terry Administrator Staff Member

    Joined:
    Aug 17, 2004
    Occupation:
    Plumber
    Location:
    Bothell, Washington
    Not completely useless. The spring load is set for 125 PSI which will dump water if the pressure builds too high. I did a lot of plumbing in a city that wanted those 125 PSI reliefs installed.

    Years later with a new inspector, things changed back to what we consider normal.
     
  10. Jeff H Young

    Jeff H Young In the Trades

    Joined:
    Feb 27, 2020
    Location:
    92346
    Pressure relief valve remote from water heater is a good thing in conjunction with a watts 210 automatic gas shut off valve at water heater. Or you need a t and p drain to an approved location.
     
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