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How many BTUs do I need?

Harry_5
Harry_5 Member Posts: 1
in THE MAIN WALL
We are thinking of replacing our boiler because it is 27 years old, and the latest estimate for service was around $500.

We have obtained estimates from two separate contractors. One quoted a Weil-McLain 115 KBTU boiler, the other a Weil-McLain 145 KBTU boiler. Our current boiler is 140K BTUs. Our house is 2100 square ft. Is there a formula I can apply to figure out how many BTUs I need?

Thanks,

Comments

  • Robert O'Connor_7
    Robert O'Connor_7 Member Posts: 688
    How Big??

    First question. Is this steam or forced hot water. Second Question. Did the contractors measure every room and window in your house (hot water heat loss calc.)or measure the radiators (EDR) (steam). Third Question (which might answer Q.#1)What exact boiler model # is it. If neither contractor did (#2) go find a contractor that will. Where are you? What state?...Robert O'Connor/NJ
  • Plumbob
    Plumbob Member Posts: 183
    another way

    Heat loss calculations are the standard way to find your answer (if anyone measures your radiators, and you have hot water and not steam heat, show them the door).

    Another way, which requires some technical knowledge and confidence, is as follows. Look in your January/February gas bill and see if it lists the number of degree-days in the billing period. Calculate the number of BTUs you have used per degree-day. Multiply by 65 if your design temperature is zero, 75 if it is -10, 55 if it is +10, and so forth. Divide by 24 to get BTU/hour used on a design day. Your new boiler will use less than that, but using this number gives you some margin. You will probably find that your current boiler is WAY too big.
  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,610
    Click on

    Free Heat Loss Calcs on the navigation bar and get the free CD-ROM from our friends at Slant/Fin. It's easy to use and you'll know for sure.
    Retired and loving it.
  • ScottMP
    ScottMP Member Posts: 5,883
    Walk across

    the street and hold up one hand then ....

    Ah I am only kidding. There is No simple way to size your boiler. You have to do a heat loss and as Dan has said it is pretty quick and painless.

    Scott

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