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Advice on heating unit

tpowls84 Member Posts: 7
Separating the utilities on a 2 family home. Currently have a steam boiler working both floor with the thermostat on the first floor. I want to run a loop of baseboard on the second floor. And separate the hot water. It's a small area. After a heat loss calculation, I'm getting a heat loss of about 20k buts. I'm interested in a combi boiler but can't seem to find one to fit such a low btu output. Any advice would be appreicated.


  • Steve Whitbeck
    Steve Whitbeck Member Posts: 669
    seperate systems

    I would not recommend any combi water heaters. They will be more trouble and cost more in maintenance.

    I would go with a small boiler and separate water heater.

    Water heaters are cheap to replace and being a commercial job the indirect would not have a good warranty. Since You will not be paying the gas bill I would go with a small cast iron boiler and a standard water heater. LOW initial cost and LOW cost of maintenance.
  • tpowls84
    tpowls84 Member Posts: 7
    Limited space

    I can barely fit a water heater in the utility room. That's the reason I considered a combi.
  • JStar
    JStar Member Posts: 2,752


    The lowest Cadet boiler is 40,000 input, or 37,000 output. For such a low heating load, you would not have enough power to supply any reasonable domestic water load, unless you installed a buffer/indirect tank with a bigger boiler, which is not the greatest for fuel efficiency. Better off going with separate heat and dhw units.
  • SWEI
    SWEI Member Posts: 7,356
    edited March 2013
    20k space heating load

    Would lead to a direct-vent gas like the RInnai Energy Saver, since there's almost nothing else that's really sized right.  I'd probably be looking at a mini-split heat pump or perhaps even an electric resistance boiler with ODR control like an  Electro or a Thermolec.  Pretty sure the Slant/Fin doesn't come that small.
  • Steve Whitbeck
    Steve Whitbeck Member Posts: 669
    cieling height

    How much ceiling height do you have?

    You could always put a 40 gallon superstor on the floor.

    And build a stand to put the boiler above it.
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