Floor Drain in a Utility Room

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Solan, Jun 16, 2008.

  1. Solan

    Solan New Member

    Messages:
    9
    I have just solved my nagging pressure / leaking PTV problem and it got me thinking pro-actively about future leak protection. I'd like to install a floor drain in my utility room where my hot water heater is housed and run the PTV into the drain.

    Here are the specs:
    - It's approx 36" X 36".
    - It sits over a crawl space.
    - It's adjacent to the Master Bath (shower, toilet are with in 3' of hot water heater).

    My questions are:
    - How big should the drain line be?
    - Can I tie into the shower drain (possibly share the P trap?)
    - Or should it have it's own trap? (I'm concerned with the trap drying out).

    Thanks,

    -Solan
  2. Gary Swart

    Gary Swart In the Trades

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    Yakima WA
    I think you'd have to have at least an 1-1/2" drain, maybe 2". It has to be trapped, and you're right about the trap drying out if not used. I don't think you can tie into the shower drain, but perhaps you could just run the pipe from the water heater to the shower and let it drain onto the shower floor.
  3. hj

    hj Moderator & Master Plumber Staff Member

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    Location:
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    valve

    If the PTV is the heater's safety valve you cannot run it to the shower at all. If it discharged while someone was in the shower it could back up out of the drain and scald them, and the same thing would happen if it drained onto the floor, except then there would be no question about getting scalded.
  4. Bob NH

    Bob NH In the Trades

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    Consider putting a hole through the floor into the crawl space and running the 3/4" pipe from the valve into the crawl space. Terminate the pipe about a foot above the ground or just below the joists. Put a slip-on plastic cap, or a piece of plastic attached with tape, over the end so wasps and things can't build a nest inside. If the TPV releases water it will blow off or through the plastic into the crawl space.

    Seal the hole around the 3/4" pipe going through the floor.
  5. Solan

    Solan New Member

    Messages:
    9
    Okay if not sharing the shower P trap then would a floor drain (with it's own trap) be the answer? I like the idea of draining into the crawl space but the potential of 50 gallons possibly draining into the crawl doesn't really sit well with me.

    I guess I would need to "prime" the trap every once & a while to keep it from drying out. Would a 2" drain be the correct size? If so does anyone have a make & model in mind that might work?

    Thanks,

    Solan
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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  7. Bob NH

    Bob NH In the Trades

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    3,317
    Location:
    New Hampshire
    You aren't going to ever get 50 gallons in the crawl space. The pressure aspect of the valve is set at 150 psi and the only way you get any significant amount at that pressure is if you have a source pressure of 150 psi.

    The usual way that TP valves open is if you have a regulator on the incoming line and no expansion tank (less than 1 gallon of leakage) or if the thermostat fails (very low leakage).

    If you have a pump and tank system that is a very large expansion tank and it usually has (should have) a relief valve that is usually set at 75 psi.

    You can make it as fancy as you want but it is not necessary.
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