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Gravity conversion boiler sizing

so doors, windows, etc. need to be measured. Measuring the radiators will tell a contractor what temperature the system will operate at.....giving you a good idea of the potential effiency of a condensing type boiler. Condensing boilers are a match made in heaven for almost all hot water radiator systems.

No.3 appears to know what how to size boilers.


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  • Paul_87
    Paul_87 Member Posts: 37
    Gravity conversion boiler sizing

    When sizing a replacement boielr for a gravity system, should you measure the radiators or the size of the rooms. I have had 3 contractors come out. Two of them measured the radiators and one of them measured all of the rooms, windows and door sizes and said the size of the radiators doesn't matter. I don't know who to believe.
  • MIke_Jonas
    MIke_Jonas Member Posts: 209
    One out of three ain't bad

    Measure the radiators for steam. Measure the heat loss of the building for hot water. Sounds like the last guy knows his stuff.

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  • Brad White_203
    Brad White_203 Member Posts: 506
    I agree, go with Number Three

    I would still ask him (or her?) to go over the heat loss numbers with you, what they mean and how that relates to the boiler selected.

    I would also add that if the new boiler is a conventional non-condensing type, that the person install a bypass around the boiler to prevent too much boiler flow and to keep the boiler running above dewpoint. I suspect that person knows this but with true gravity systems being converted to pump operation for the first time, this sometimes is not done.
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