Anyone use a Watts 80 ballcock thermal expansion valve?

Discussion in 'Toilet Forum discussions' started by imac567, Dec 1, 2012.

  1. imac567

    imac567 New Member

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    As an alternative to an expansion tank the Watts 80 is recommended for pressure relief when connected to a closed system (county or city water). Anyone use one? Do they work and how reliable are they? Thank you.
     
  2. zl700

    zl700 DIY Senior Member

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    They waste water and fail, wasting even more water.
    Best choice to control thermal expansion is a potable water expansion tank pre charged properly at the water heater inlet.
     
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    FWIW, a properly operating expansion tank does not waste water, a pressure relief valve will. An ET helps to maintain a more even pressure, an relief valve only puts a top limit on it, not hold it to a more proper level. A relief valve may be a good backup, but they can fail as can an ET, then you have nothing to prevent overpressure and potential leaks. Personally, I would not use one as my primary closed system solution.
     
  5. Gary Swart

    Gary Swart In the Trades

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    There a very old, shop worn saying, "If is ain't broke, don't fix it". I think that applies very well to this question. A thermal expansion tank works very well, does not waste water, is easily replaces when it fails, and is inexpensive. Why go look for an alternative?
     
  6. imac567

    imac567 New Member

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    I see your points, all of them... I'm looking at an Amtrol ST-5 2 gallon, looks good because I really wanted a lined tank, for corrosion reasons. If anyone knows of a better one, Please let me know. Thank you.:) By the way is there a certain distance it has to be installed from the hot water heater? I'd like it to be in my outside pump room just after the pressure regulator.
     
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    It can be installed anywhere on the cold supply side after the PRV. But, there should be no shutoff valve between the WH and the new expansion tank. This is to ensure it can do its thing when the WH starts to run. They don't last forever, but do last a number of years. Adjust the precharge to your static water pressure before installation.
     
  8. imac567

    imac567 New Member

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    PRV? Pressure Regulating Valve?
     
  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Pressure reduction valve or whatever is causing your system to be a closed system (could be a check valve).
    There should be no valve between the ET and the WH.
     
  10. johnnycragg

    johnnycragg New Member

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    How about, installing a brass wye at hot side of washing machine and with a braided stainless steel washer hose connected to a thermal expansion tank, and connect other hose to washer. now you have hot side of water line with expansion tank and no plumber charges. diy.
     
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Potable water expansion tanks are NOT rated for hot water...only for cold, so do not put it on a hot line. You could do this on the cold water line in that manner.
     
  12. Reach4

    Reach4 Well-Known Member

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    I think that is as good as it gets. http://www.amtrol.com/media/documents/thermxtrol/MC4090_06_15_ThermXtrol_Brochure.pdf While their working temperatures is rated at 200F, you usually install them on the cold water line. As long as the precharge was a few PSI higher than the water pressure (keeping the tank normally empty to not waste hot water), the hot water side would be fine too.
     
  13. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    The instructions specifically say to install it on the cold water line, NOT THE HOT!
    http://amtrol.com/media/documents/thermxtrol/9015087_06_15_TXT_IO.pdf

    An expansion tank designed for hydronic heating (i.e., with a boiler) are not designed for potable water, and can handle higher temperatures. WHile this one is designed for potable water, the life expectancy, if installed on the hot side, will be degraded.
     
  14. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    duplicate
     
  15. Reach4

    Reach4 Well-Known Member

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    It did say to install it on the cold. That is the normal way. It did not say it was only suitable for the cold IMO. It said it was good to 200F working temperature.

    That document LAO said to match the precharge to the water pressure. Yet it does not say or imply that setting the precharge 5 psi higher than that is wrong. I think that would be preferable for a city water system, since the pressure can vary. It is advantageous to have the tank still empty, even if the city water pressure rises some.
     
    Last edited: Oct 24, 2015
  16. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Depending on the temp you run your WH, and where the ET is located, during expansion, some hot water could reach the ET. But, it won't be exposed to extreme temperatures for extended periods of time as if it were on the hot side. Consider that in some applications, a WH could be running at near that temp, and if it failed, the temp would get to over that 200-degree limit before the T&P valve released, hopefully, diluting the tank to prevent it from flashing to steam and blowing up the building. Unless the instructions say it is allowed to be installed on the hot side (it would say cold OR hot supply), it is pretty clear, install on the cold side.

    The neutral point of the bladder is when it is the same pressure as the water pressure applied on the other side of the bladder...otherwise, it is constantly being stretched. If installed because a PRV was installed, as long as that's working properly, the city pressure side is mostly irrelevant.
     
  17. johnnycragg

    johnnycragg New Member

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    The point of install is not on the water heater, so its not hot most of the time, if hot water expansion occurs with cold water shut off at heater, expansion would be absorbed by tank at washing machine, when pressure in tank was initially charged in tank, I think most people don't check after a year, eliminating its purpose.
     
  18. hj

    hj Moderator & Master Plumber Staff Member

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    A ' heating expansion tank" is installed on a "sealed system" which has the oxygen "evacuated" out of it, so rusting is NOT a factor, which is also why the system is installed with black iron piping. A "potable" water expansion tank is internally glass lined to protect the metal against corrosion.
     
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