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BTU's Needed?

DonK Member Posts: 1
Great site.

I am converting to gas heat from oil. Two story stone house, outside Philadelphia PA, is 85 years old, 1,600 square feet.

Two estimates s far, both through the flu venting. One is for a 96,000 BTU Burnham gas boiler. The second is for 132,000 Buderus boiler.

Why the large disparity in recommended BTUs?

Thanks in advance for your help.


  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    Why the large disparity in recommended BTUs?

    Because at most one of those contractors did a heat loss calculation?
  • Alan (California Radiant) Forbes
    Jean-David is right.

    But it's not unusual for bids to come in without heatloss calculations. The questions is, who do you choose to do the work.

    If I were you, I would call a reliable contractor and pay to have him do the heatloss calculations for your home. If you click on "Find a Contractor" above, there seems to be many in your area and I recognize a few of them who are quite active and knowledgeable here on The Wall. With these calculations in hand, you can give copies of them to other contractors that you ask to bid on your boiler replacement. That way, everyone is bidding on at least the same calc's.

    The contractor that does the calc's. may even give you a bid and offer to credit back the charge for the calc's. if he does the work.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • icesailor
    icesailor Member Posts: 7,265
    A lot of guys:

    A lot of guys (or a few) would have done a complete heat loss for the building. Which means room by room. Measured installed radiation and done a comparison to what is there as to what is needed. Compared it to the boiler that is there, and on the quote, made some measure of letting you know that the calculations were done, and because it was done, your boiler was either OK or XX oversized so you could use a smaller or less expensive boiler and any other important things you can suggest.

    Some are only interested in price. The rest are  interested in price and quality. But I would never give my worksheets to a potential customer. Maybe once I have the job or started, but never so they could pass it around for others to say "No matter what the price is, I'll do it for $100.00 below that".