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We are in the process of installing a staple up radiant floor system. The load calls for a 60,000 BTU input boiler following heat loss calculations performed by manf. rep. We would like to install a Burnham indirect hot water heater which would require us to increase the input to 140,000 BTU'S . Is it worth it to increase the size of boiler just to satisfy hot water needs or should we just go with a standard storage type water heater and use the smaller in put boiler for heating only.  


  • SWEI
    SWEI Member Posts: 7,356
    none of the above

    Unless you have huge DHW demands (like a giant spa tub with 3/4" or 1" supplies) you can probably get by just fine with a smaller boiler.  You'll get better turndown and far less cycling during shoulder seasons that way.

    Is your heat loss calc expressed as building loss or boiler input or both?  Did they assume the same boiler efficiency as the model you're considering?
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