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Size of Boiler

sammin2290 Member Posts: 1
I am looking to convert from oil to gas and we have had multiple plumbing companies come and give us estimates on gas boilers. We have had a pretty significant difference in the size of the conventional boilers that we were quoted for. One recommended a boiler that was a 132,500 standard BTUs (Buderus) while another recommended a 105,000 standard BTUs (Burnham). 
Our home is 1470 square feet (however, that is not including the basement, which is heated and another 700 sq ft) and has 3 zones. We want to make sure that we are not getting a boiler that is oversized, lowering its efficiency. 


    HVACNUT Member Posts: 5,481
    edited July 2020
    Download the free Slant/Fin heat loss calculation app. You'll find the boiler you need will be closer to 105. Probably much less. Base it on 2170 sq ft. The full heated living space. 
    Going by the existing boiler doesn't work unless it was sized correctly and there were no upgrades done in insulation, windows, etc. Measuring the output of the radiation only tells you whether or not there's enough of it.
  • Ironman
    Ironman Member Posts: 7,225
    See my answer to your post on HVAC-talk.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.