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Can you use a condensing boiler with a water heater

CBRob Member Posts: 273
So I have just installed a triangle tube condensing boiler for a snow melt system. We left some stubs on the primary loop for heating DHW sometime in the future.
There are currently a couple of 8 year old 75 gas water heaters that supply the dhw to the house.
When they are removed we will put in a new indirect water heater, but in the mean time.
Is there anything to be gained by trying to heat dhw in those tanks by way of a heat exchanger and circ pump?

I know its a long shot... it just got me wondering.


  • Zman
    Zman Member Posts: 7,572
    Any idea why you have 2 tanks now? That is a lot of storage. If you add a couple of circulators, a heat exchanger, and some misc piping and parts you could do what you describe. It would probably be ~25% more efficient than what you have now assuming you disconnect the gas to your heaters and block the vent so you stop losing the heat up the vent.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • CBRob
    CBRob Member Posts: 273
    Its a 2nd home that I caretake at a ski area in Colorado.

    The two 75 gallon heaters must be overkill, only a 4 bath home.
    The hot b vent going though the small attic adds to an ice dam problem too.
  • mattmia2
    mattmia2 Member Posts: 9,734
    Are there a lot of large tubs in these baths they are trying to fill?
  • CBRob
    CBRob Member Posts: 273
    edited November 2019
    Yes, there are 2 jacuzzi tubs...
    But I doubt they get used much.

    There is an outdoor hot tub too, I bet it's just kids taking baths.

    I'll have to talk with the owners about their needs