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Thread: Higher temperature water heater overflow valve?

  1. #16
    DIY Senior Member Melissa2007B's Avatar
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    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...
    Melissa
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  2. #17
    DIYer, not in the trades LLigetfa's Avatar
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    Quote Originally Posted by Melissa2007B View Post
    Already explained why we can't do that...
    Then run a recirc to a location more convenient.

  3. #18
    Retired Defense Industry Engineer jadnashua's Avatar
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    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.
    Jim DeBruycker
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  4. #19
    DIY Senior Member Melissa2007B's Avatar
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    Quote Originally Posted by jadnashua View Post
    Most of the retrofit recirc systems do not need a dedicated return line...if you have one, great, but it's not required.
    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.

    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.
    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...
    Melissa
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  5. #20
    Moderator & Master Plumber hj's Avatar
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    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.
    Licensed residential and commercial plumber

  6. #21
    DIY Senior Member Melissa2007B's Avatar
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    We dont have a regulator yet.
    Melissa
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  7. #22
    DIYer, not in the trades LLigetfa's Avatar
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    Quote Originally Posted by jadnashua View Post
    Most of the retrofit recirc systems do not need a dedicated return line....
    Quote Originally Posted by Melissa2007B View Post
    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.
    I do not suggest a retrofit without dedicated return. Those have thermostatic valves that stop the flow once the water at the POU is up to temp. It does not put scalding water into the cold line. It also does nothing to combat stacking. To combat stacking, the recirc needs to be continuous to blend the water in the tank.

  8. #23
    DIY Senior Member Melissa2007B's Avatar
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    I'm not sure what you mean then, or how it can be done.

    It was my understanding that a recirc system needs to create a loop of all the hot water line, going all around the house, then a small pump pumps it. But the bottom of the house is covered in insulation and plastic, so I'm not clear how an insulated recirc loop could be done.
    Melissa
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  9. #24
    DIYer, not in the trades LLigetfa's Avatar
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    If the intent of the recirc is to have ready hot water at all the faucets, then yes, what you describe is true. If all you want to do is use a recirc to prevent temperature stacking, then the recirc does not have to go all the way out the the farthest faucet or to any faucet for that matter. It simply needs to draw off a small continuous supply of hot water from the top of the tank and send it back down to the bottom.

  10. #25
    DIY Senior Member Melissa2007B's Avatar
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    Quote Originally Posted by LLigetfa View Post
    If the intent of the recirc is to have ready hot water at all the faucets, then yes, what you describe is true. If all you want to do is use a recirc to prevent temperature stacking, then the recirc does not have to go all the way out the the farthest faucet or to any faucet for that matter. It simply needs to draw off a small continuous supply of hot water from the top of the tank and send it back down to the bottom.
    Yes, I understand that, but I should try using cold water for the humidifier first, eh?

    As far as circulating around the whole house, I'd love to, but the cost...

    But it's real obvious now, that we gotta get that pressure regulator on the input water supply to the whole house!
    Melissa
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  11. #26
    Retired Defense Industry Engineer jadnashua's Avatar
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    You do not understand the retrofit recirculation systems' operation. Plus, as I said, when you add a PRV, you MUST add an expansion tank. THe PRV will only prevent the supply's pressure from rising, it will do NOTHING about the rise from the WH heating the water except possibly make it worse.

    A retrofit system uses a cross-over at at least one sink. It has a thermostatically controlled valve in it. It is usually set to somewhere around 100-105 degrees. WHen the water there reaches that point, it shuts of. On most, the pump keeps running, but the valve is closed. So, the 'cold' water will never get hotter than the setting of that crossover setting. The only one I know of where this is user adjustable is the RedyTemp unit. Now, depending on the layout of the house, that one may not run long enough to combat the full stratification effect.

    But, while that effect is possible, are you SURE that's what's causing the T&P to discharge? Do you get nearly boiling water out of the hot tap? If not, then it's a pressure issue, and the stratification is not severe enough to create your problem, it's all pressure. A closed system without an expansion tank can easily get to high enough pressure to open a T&P safety valve. It happens all the time. You MUST have somewhere for that expanding water to go, and you seem to be ignoring the fact of an expansion tank. Assuming you have a PRV installed, insist they also add an expansion tank - any good plumber would know this, and, it's required if you get a permit and have it inspected.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  12. #27
    DIY Senior Member Melissa2007B's Avatar
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    Quote Originally Posted by jadnashua View Post
    You do not understand the retrofit recirculation systems' operation. Plus, as I said, when you add a PRV, you MUST add an expansion tank. THe PRV will only prevent the supply's pressure from rising, it will do NOTHING about the rise from the WH heating the water except possibly make it worse.
    Apparently I don't understand. At Home Depot they were showing me a water pressure regulator that they said could be put before the water enters the house and keep the pressure from ever going too high after it enters the house. Are we talking about the same thing??? They didn't mention any tank.


    A retrofit system uses a cross-over at at least one sink. It has a thermostatically controlled valve in it. It is usually set to somewhere around 100-105 degrees. WHen the water there reaches that point, it shuts of. On most, the pump keeps running, but the valve is closed. So, the 'cold' water will never get hotter than the setting of that crossover setting. The only one I know of where this is user adjustable is the RedyTemp unit. Now, depending on the layout of the house, that one may not run long enough to combat the full stratification effect.
    What people here have been suggesting is just a loop around the house, and a pump. Then the temp gets set in the water heater where it gets set now, and stays that way.

    But, while that effect is possible, are you SURE that's what's causing the T&P to discharge? Do you get nearly boiling water out of the hot tap?
    NO, and the pressure appears to be causing it. I said the pressure has been between 80-99 PSI just tonight. I'm convinced it's the pressure.

    If not, then it's a pressure issue, and the stratification is not severe enough to create your problem, it's all pressure.
    YES. I agree.

    A closed system without an expansion tank can easily get to high enough pressure to open a T&P safety valve. It happens all the time. You MUST have somewhere for that expanding water to go, and you seem to be ignoring the fact of an expansion tank.
    YES, because the city water pressure is 80-99 PSI coming INTO the house. What good will an expansion tank do??? It needs to be regulated before it enters the house, which is what Home Depot suggested, pending my measuring the PSI, which I just did.

    Assuming you have a PRV installed, insist they also add an expansion tank - any good plumber would know this, and, it's required if you get a permit and have it inspected.
    NOTHING is installed yet, except the PRV on the water heater, but it's being caused by city water pressure, NOT temp.

    Are we on the same channel?

    http://www.homedepot.com/h_d1/N-5yc1...1#.UQtHVM_jFyI
    Last edited by Melissa2007B; 01-31-2013 at 08:41 PM.
    Melissa
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  13. #28
    Jack of all trades DonL's Avatar
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    You can not compress water.

    When water is heated it expands, and requires more room. If no extra room to expand then pressure goes up.

    Is that hard to understand ?

    It is simple really.
    Theory only works perfect in a vacuum.

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  14. #29
    DIYer, not in the trades LLigetfa's Avatar
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    Quote Originally Posted by DonL View Post
    You can not compress water.

    When water is heated it expands, and requires more room...
    Water does the same thing when it freezes.

  15. #30
    DIY Senior Member BobL43's Avatar
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    Quote Originally Posted by LLigetfa View Post
    Water does the same thing when it freezes.
    Yes it certainly does, about 9% expansion
    I am definitely not a pro plumber, but I am a pro crastinator

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