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single zone system size?

I am bidding on a job for a good friend. I have enough experience to complete the job with the highest quality. It is a single zone two car garage 450 sq ft. 1/2 in pex in 6in concrete. This system is to be a heat exchange system. Two pumps, natural gas water heater 50 gallon, is 50 gal big enough? I was thinking 2 gpm loop flow a taco 006?. a small heat exchanger, but which one to use and what size? Do I need flow meters on both sides? Can the copper loop be 3/4 in? The rest of the water heater is going to provide hot water to a 3/4 bath shower only.


  • Gordy
    Gordy Member Posts: 9,546
    edited January 2012
    Heat loss

    All these questions you ask can only be properly answered with a heat loss calc.

    The only thing I can tell you is it would be 2- loops at 225' counting leaders.

    You only need flow meters on the return. For what you are doing they are not really necessary if the loop lengths are equal with in 10%.

    3/4" copper will carry 40,000 btus at 4 gpm 20* delta t

    A water heater tank type, or tankless is not a boiler.

    If you use a tank style water heater with a HX the HX should be double wall since you are using the potable side for domestic use.

    Cant tell you if a 50000 btu wh is big enough with out a heat loss.

    For same reason cant tell you what size HX to get. What loop flow rates need to be, pump size, water temps.

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