Routing pressure relief valve line

Discussion in 'Water Heater Forum, Tanks' started by dabiz7, Mar 3, 2009.

  1. dabiz7

    dabiz7 New Member

    Feb 27, 2008
    I am wondering about the best method to route the drain line attached to the temp&press relief valve in my water heater. My current heater is in the middle of the house, in a laundry closet that has no floor drain. house is on a slab. Current water heater has a 3/4 copper tube soldered to the valve and running down the side of the heater. With this setup, if the valve blows, water all over the wood floor and I am screwed.

    I am considering the feasibility of running the the relief tubing into the PVC washer drain in the closet. My concern is, will the PVC drain pipe withstand the high temp of the water that would be discharged from the relief valve if it tripped? I didn't think PVC drain pipe would stand that high of temp (210 F ?) I really don't have any other solution. Any other ideas??

    thanks !!!
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    This is what I think I'd do (it'd be much easier done while installing the tank, though):

    I'd install the tank in a pan. You'd need to basically plug the outlet so it can hold some water. I'd also install a WAGS valve The valve will shut the water off if it detects 1/2" of standing water. If it is a gas WH, it can also be set to disable the gas valve. If installed by a certified installer, comes with a big warranty against leak damage. Made by a well-known manufacturer.

    I think I saw a pseudo pan that you can install afterwards that glues to the floor to contain the water instead of setting the WH into it. Probably doesn't work as well, but might work for you if you're not willing to do the work to insert a pan underneath.
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  4. jimbo

    jimbo Plumber

    Aug 31, 2004
    San Diego, CA
    I have seen a lot of water heaters with TP discharged to laundry standpipe. I don't know if they accept that anymore, as it would still pose a potential safety hazard if you were near it. The PVC would not melt at that temp.

    Around here, the common method for your setup is to put a Watts 210 temperature activated gas shut off in the TP hole on the tank. Then you have to put a 3/4" 150 PSI pressure relief valve on the main water supply, on the house side of any PRV or shutoff valve.
  5. Master Plumber Mark

    Master Plumber Mark Master Plumber

    Feb 6, 2005
    Sensitivity trainer.. plumber of mens souls
    indianapolis indiana - land of the free, home of
    do as jimbo says

    when you have no other recourse ,

    pipeing the t+p valve to the washing machine box

    is acceptable in my book.... I do it all the time
  6. james.mcewan

    james.mcewan New Member

    Mar 4, 2009
    DUX airoheat

    how do DUX airoheat hot water units work?
  7. hidden 1

    hidden 1 New Member

    Mar 13, 2009
    Hi ,i didnt have a drain in floor either and had the choice of a adjustable pressure relief valve before the heater on cold line(temp adjusted just below the one on water heater)- then emptied out in washer drain.Or to run off that existing prv to the same drain.sealed mess!
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