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Heating with hot water for potable use !!!!!!

heatguyheatguy Posts: 102Member
I am currently working at a site where they are using the hot water to heat with.This is a large high end condo.there are air handlers and  diverting valves in each unit.The common water is supplied at 180* with a mixing valve to temper the water for potable use.My concerns  are when you are not using the heat the water sits stagnant in heating coil in air handler until you turn it on again,then that whatever temp stagnant water is mixed in with the rest ,so  are  they   brewing legionnaire's in these coils ? i called the state and was told if its existing and i service it i accept no liability , being a licenced plumber i am still concerned  what do you think ?


  • bob eckbob eck Posts: 863Member
    hot water for heating

    if you want to be safe use a plate heat exchanger. run water heater 180* water through one side and run water in the duct coils in the other side.

    the two different waters will never touch.
  • Jamie HallJamie Hall Posts: 10,548Member
    I'll go with Bob

    and use a heat exchanger to separate the two circuits.

    And I'll add that, while I don't recall the Code exactly (something about time...), I do recall that in another life, somewhere back there, when I was a plumbing etc. inspector, I'd never have permitted mixing heating and domestic water without using a heat exchanger -- and an RPZ backflow valve or air gap for filling the heating circuit.

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • Open System

    I don't like open systems; not because they are dangerous since I've never heard of a case of Legionnaire's from this and as long as the piping is approved for potable use, I don't believe there's anything in the code to disallow it.  I don't like it because it's usually the low bid.
    Often wrong, never in doubt.

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  • Mark EathertonMark Eatherton Posts: 5,843Member
    The reason you don't hear about it....

    is because, per the CDC, "It is THE most misdiagnosed disease in the world..." Usually misdiagnosed as "common bacterial pneumonia."

    It happens everyday. All coper systems are less susceptible than PEX systems, but it is still present.

    Every person reading this has been exposed to the bacteria at one point in time or another. It is a matter of concentration of the bacteria, and exposing yourself while your immune system is depressed.

    This has been beat up here ad nauseum by myself and professor Yates,

    Do a site search for legionella pneumophila and se what comes up.

    If I had my way, it would be illegal to do this type of system, and as soon as the lawyers get ahold of it, it will be...

    Just a matter of time.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Charlie from wmassCharlie from wmass Posts: 4,068Member
    Its illegal in Massachusetts

    Funny how it must only be us that have the bacteria that cause disease. It is legal in Connecticut, New York. New Hampshire, and Vermont. Even if it is legal I would not do it.
    Cost is what you spend , value is what you get.

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