Higher temperature water heater overflow valve?

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by Melissa2007B, Jan 30, 2013.

  1. Melissa2007B

    Melissa2007B New Member

    Messages:
    102
    Location:
    Denver, CO
    We're in the Denver burbs at about 5800 feet, which contributes to this. ( water boils at around 203 degrees here )

    This is the second time in 2 years I need to replace this valve and I'm tired of it. Why?

    We have a Aprilaire whole house humidifier that requires a 1/4" line of regulated temp 140 degree water from the top of the water heater. When it runs, it causes "stacking", where the trickle of hot water from the top causes a trickle of cold coming in the bottom, and the gas flame to come on to heat it, overheating the top.

    I just replaced this overflow valve, 2 years ago if I recall. I think they said it turns on at around 170 degrees?

    Right now it's dripping in the pan, and someone who was in the crawl space just told me there's a puddle down there now.

    We can't afford extravagant heroic solutions to this, like a circulating loop for the hot water, or all that. We're barely paying the bills here.
    ( This is a modular house and we'd love to do the loop thing, but there's insulation and plastic over the whole bottom down there. )

    So do they make valves like this that are a higher temperature? Like maybe 190 degrees?
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,809
    Location:
    New England
    A humidifier will work with using the cold water as the input. It might work better with warm water, but from the problems you're having, I'd just switch it to the cold side and forget about it. FWIW, my AprilAire unit has been using cold water as the feed for years, and works fine.

    There are higher trip T&P valves, but they wouldn't be a good idea at your altitude, even if it would fit (they're larger in diameter). They would also void the CSA certification, I think, and if you had problems with the tank, (it could blow up!) your insurance may not pay up, if you were still around to try to collect. http://media.wattswater.com/F-SF.pdf
  3. Melissa2007B

    Melissa2007B New Member

    Messages:
    102
    Location:
    Denver, CO
    I asked Aprilaire and they recommend only 140 degree regulated. Maybe it has to run much longer on cold. Remember, our cold is very cold here in winter.
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,809
    Location:
    New England
    My wintertime cold water can approach freezing, and yours can't be colder than that or it would freeze up. I've measured 33-degrees after a cold spell. Most T&P valves are rated to open at 210-degrees...because of your altitude, they may specify a lower-temp one. Keep in mind, the 'normal' 210-degree one would allow the water to flash to steam, should it ever be triggered for temperature and this is VERY unsafe.

    Running your WH at 140-degrees would also require a tempering valve per national code for the rest of the house.

    Are you sure that it isn't tripping because of pressure? If you have a closed water supply system and don't have an expansion tank, it could easily be opening because of pressure rather than temperature. Pick up a water pressure gauge with a second, tattle-tale hand, leave it connected to say the drain valve of the WH or your washing machine supply, and see what it says about pressure peak after 24-hours. It is very easy to get pressures to exceed the 150# of the T&P valve, and have it open because of that.
  5. Melissa2007B

    Melissa2007B New Member

    Messages:
    102
    Location:
    Denver, CO
    Not sure. Our outside hose water here has been known to go up to 90 or so PSI.
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,809
    Location:
    New England
    Code requires a PRV and an expansion tank when the supply water pressure exceeds 80psi...I'm thinking your problem may be more pressure than temperature. A PRV and an expansion tank may solve your problem, but first test the pressure. Remember, the T&P valve has TWO ways it can open.
  7. Melissa2007B

    Melissa2007B New Member

    Messages:
    102
    Location:
    Denver, CO
    Last edited: Jan 30, 2013
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,253
    Location:
    Cave Creek, Arizona
    T&P valves open at 200 degrees, not 170, and therefore, NO ONE, makes "higher temperature" version, since that could create an unsafe condition in the water heater. Your diagnosis of the problem, and thus its cure, may be faulty.
  9. Melissa2007B

    Melissa2007B New Member

    Messages:
    102
    Location:
    Denver, CO
    Last edited: Jan 31, 2013
  10. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,236
    Location:
    Land of Cheese
    I too have an Aprilaire humidifier tapped off the cold water supply. Been working fine for over 10 years.
  11. DonL

    DonL Jack of all trades

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    3,812
    Location:
    Houston, TX
    Last edited: Jan 31, 2013
  12. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,809
    Location:
    New England
    If your static pressure is over 80#, or it peaks higher, you need two things: a prv AND an expansion tank. Your existing plumbing may already be closed (i.e., a check valve from the water company, or maybe installed during construction), and without a working expansion tank (you might have one, but it has failed), the act of heating water WILL raise the pressure high enough to cause the T&P to release water unless some other weak point is bleeding off the pressure. The pipes are essentially rigid, and can't blow up like a balloon...something will give when the pressure rises. That's the purpose of the expansion tank. The two (prv + expansion tank) work together to keep the house pressure stable.
  13. Melissa2007B

    Melissa2007B New Member

    Messages:
    102
    Location:
    Denver, CO
    I just got the gauge from Home Depot and hooked it to the cold water line at the washing machine. It started out at 80 PSI about 40 minutes ago, and a check just now shows the red needle sitting at 92. But that red needle is very loose, a transient spike could kick it way up.

    The plumbing lady in Home Depot showed me some 3/4" and 1" regulators that she said can be put on the main line coming into the house, can withstand up to 300 PSI and only allow 50-70 PSI into the house.

    Update: Less than 2 hours and the red needle is up at about 98 PSI.
    Last edited: Jan 31, 2013
  14. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,236
    Location:
    Land of Cheese
    50 psi in a house is more than enough. I would speculate that most homes range from 30-50 psi.
  15. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,826
    Location:
    NW Ontario, Canada
    Put in a recirc pump and line. It will stop the stacking and give you hot water right away from a distant faucet.
  16. Melissa2007B

    Melissa2007B New Member

    Messages:
    102
    Location:
    Denver, CO
    Already explained why we can't do that. The house is UBC modular, put on a foundation, but has insulation and plastic under it. No idea what it would cost...
  17. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,826
    Location:
    NW Ontario, Canada
    Then run a recirc to a location more convenient.
  18. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,809
    Location:
    New England
    Most of the retrofit recirc systems do not need a dedicated return line...if you have one, great, but it's not required.

    Anyway, the tattle-tale hand is doing what it's supposed to...recording the maximum value. If you leave it overnight, and particularly, after a big hot water usage which would cause lots of water to have to be reheated, you'll probably notice it peaking much higher. This is specifically what an expansion tank is designed to prevent. It would still leave you with the static pressure at whatever the street is providing, but it would prevent the peaks and may solve the weeping T&P valve issue.
  19. Melissa2007B

    Melissa2007B New Member

    Messages:
    102
    Location:
    Denver, CO
    I checked into that, and the way they do it is to use the cold water line at certain times of day, which can put scalding water in the cold water line.

    Why not just have the regulator installed at the input to the house? The most expensive one ( 1" ) is under $100 plus the plumber. ( knowing plumbers, it could be $500 for them? ) Or maybe a handyman can do it...
  20. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,253
    Location:
    Cave Creek, Arizona
    I set my regulators at 75 psi. Open a faucet to drain off the pressure and restore it to the normal level. DO NOT use any hot water and see if it rises again. If so, your regulator is bad, and 92 psi is the pressure in the city mains.
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