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SIMA Member Posts: 4
I have 35 x 45 sq. ft. residential building with four apartments ( 2 floors) and basement. Three contractors came and each of them gave 3 different size of boiler. These are the sizes they gave; 210k btu/hr, 220k btu/hr and 150 btu/hr.
The building has two floors and a basement. With the bldg size 35 x 45 so approx we have 4,725 sq.ft. What is the right size of boiler i shld choose?

I appreciate your help.



  • Jamie Hall
    Jamie Hall Member Posts: 22,196
    Not enough information. To do the job properly, you need to do a heat loss analysis on the building. Then you start to have enough information.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • kcopp
    kcopp Member Posts: 4,306
    really not enough info....how ever my gut tells me that the 210 and 220 are way too big.
    nicholas bonham-carter
  • SIMA
    SIMA Member Posts: 4
    Hi Hatterasguy,

    Thank you for taking time to give an idea.
    I live in Montreal Canada and we get upto -45 with the windchill factor.
    Basement has a bachelor size apt. so, we need to heat it same as the other apartments.

    Kcopp and Jamie Hall,

    Sorry, but I do no know how to get a heat loss analysis.
    Can the contractor do this analysis for me?
    Thank you.

  • kcopp
    kcopp Member Posts: 4,306
    The contractor who is doing the install SHOULD/ Must do this for you.
    Did they tell you...did you ask how they arrived at those numbers?
    Otherwise they are just guessing.
    More info....
    What type of radiation?
    How much?
    What is in there for a boiler now?
    How big?
  • RobG
    RobG Member Posts: 1,850
    I haven't re-read the post so if this has been mentioned I apologize. The first thing and the best bang for the buck is to air-seal the home and do as many insulation and window upgrades as possible. Those simple things will lower the heatloss of the home in turn allowing you to have a smaller boiler and smaller utility bills. Then have the heatloss done.
  • SIMA
    SIMA Member Posts: 4
    Guys thank you very much for your insights.

    This is our first house and our first winter in a house. We lived in a condo and had electric baseboard heaters so never had problems.

    The house was built in 1976 and had the same furnace since. With regards to its insulation and kind of windows this house has... I don't know.

    So your inputs is very much appreciated, especially if you have experience using boiler/furnace. We have hot water radiators.

    This are the only information I got at this time, and if anyone can give us a good advice according to your experience, we are grateful. It is much pain in the pocket that we spent almost 10K for the whole winter heating the whole house.

    So I will we waiting for any useful idea.
    Again, thank you.
  • SIMA
    SIMA Member Posts: 4
    This is not a single house but rather a fourplex. sizes are the following: 2 x 3 bedrooms ( 5 1/2 size apartment); 2 bedroom (4 1/2 size apt.); 1 bedroom (3 1/2 size apt) and 1 bedroom apt in the basement(3 1/2 size).