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gpm on tank water heaters

Snowmelt Member Posts: 1,288
is there a chart or can anyone tell me instead of sizing water heaters to the gpm of whats needed is there a chart that can give an estimate of how much water comes out of lets say 2 - 75 gallon water heaters and 1 65 gallon storage tank. that way I can say with 2 - 75 gallon i can give you 250 gallons of water in an hour and with a stage tank i can give you ex amount of water.


    EBEBRATT-Ed Member Posts: 10,213
    Look at the manufacturers instructions. There are many variables:

    Inlet domestic water temp
    Outlet domestic water temp
    DHW temp is usually figured at a 100 deg rise

    Then you have to look at the boiler side:
    variables are boiler water temperature
    TD on boiler water temp
    GPM flow

  • Larry Weingarten
    Larry Weingarten Member Posts: 2,278
    Hello, Tank type heaters should have a "first hour rating". It combines the stored hot water with what the unit can produce in an hour. That's your answer. ;)

    Yours, Larry