Water Heater Relief Discharge

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Plumbcatastrophe, Feb 17, 2006.

  1. Plumbcatastrophe

    Plumbcatastrophe New Member

    Jan 22, 2006
    Am I okay if my water heater relief discharge goes into a drip pan that can overflow, if needed, to the dirt crawlspace?
  2. prashster

    prashster New Member

    Dec 7, 2005
    novice's opinion

    (not a pro): I think the 'overflow' tube is actually a pressure relief tube. So, if the valve on the top pops, you'll get steam out of there and minimal actual liquid water. Discharging into an overflow pan won't do anything in that case.

    If your water heater develops a leak, it won't be from that tube. I saw someone put their whole water heater into an overflow pan with a moisture-activated alarm and a valve that shut off the cold h2o supply to the heater in the event of a leak. If he hears hear the alarm, he might be able to drain the residual water through the drain valve (at the bottom) b4 the overflow pan is filled. If he doesn't hear the alarm, then at worst he'll get only a tank's worth of water damage.

    Another note: some people say it's good to 'pop' the valve every year to test that it works. Others say not to, because it's a pain to get closed again. Check with someone who knows for sure b4 'testing' it. I haven't havd the guts to try it yet.
    Last edited: Feb 17, 2006
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  4. Gary Swart

    Gary Swart In the Trades

    Sep 1, 2004
    Yakima WA
    I'd say it depends on the soil in the crawl space. I install a water heater for my daughter awhile back and set it in a pan. Then while exploring how to best run the drain for the pan, I realized that her house is build on old river bed. So, I just ran the drain into the crawl space because you couldn't saturate that ground if you ran water in it for a month. Unless you have that type of soil, I'd suggest you run the pan overflow to the outside. When a PRV pops, it's just a small stream of water anyway, and if the tank goes south, they will leak but not suddenly fall apart. I suppose a moisture alarm in the pan wouldn't hurt, but I would lose sleep over not have one. Now, if the tank is over finished living space, you certainly will want the overflow to either go outside or into a drain.
  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
    its OK

    the idea is to keep the water from the pressure valve from
    flooding out your home........

    you will probably NOTICE the water in the pan in either a few minutes or days....

    on average people will notice the water pretty quickly if it is in
    the living area or laundry room....

    you will probably HEAR the water dripping into the pan

    Its a pretty good set up the way it is and
    its far better than the alternative.....of a major flood

    and you really SHOULD NOT just pipe that pop off pipe
    directly into the crawl space the you could really flood the crawl

    I have seen the damage form this.....
    and I was almost on the hook for the water damages it caused

    the hot water from the heater can literally create a STEAM JUNGLE
    affect in the crawl space if it goes on for a few weeks....... and this will
    actually warp your ply-wood floors and the joists .......

    you cant immagine anyone letting this pop off
    for any length of time but it happens... quite often

    if they cant see it happenning
    right before their eyes, or hear the water running
    its usually ignored

    out of sight , out of mind...
    Last edited: Feb 18, 2006
  6. Gary Swart

    Gary Swart In the Trades

    Sep 1, 2004
    Yakima WA
    My suggestion was not intended to imply that one should allow water to run indefinitely into the crawl space. The overflow from the PRV or leaky tank should be noticed and dealt with within a reasonably short time.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona

    The safety valve is supposed to open at 200 degrees, long before it reaches the steam temperature, so it will be all water.
  8. jimbo

    jimbo Plumber

    Aug 31, 2004
    San Diego, CA
    Your local code will answer the question. Some areas would not accept the overflow discharging into the drain pan. Some would.
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