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Calculating Flow to Radiators

Jesse_3 Member Posts: 3
I was wondering about adding or moving radiators within a hot water heating system. If you were remodeling and wanted to do this, I was wondering if there is a formula for calculating if your boiler has enough capacity to supply the new boilers or account for the change of location of a boiler.


  • ALH_4
    ALH_4 Member Posts: 1,790

    In a hot water system, It's less an issue of whether the boiler can heat the radiators than it is an issue of whether the boiler can heat any additional area you may be adding. The maximum output of the boiler needs to match the heat loss of the structure it is heating at design load.

    You need a heat loss calculation done on the entire house including the addition in order to compare it to the output of your existing boiler. Are you usign TRV's?

  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928

    I'd really suggest that you enlist a hydronic heating pro as early in the remodeling process as possible. While they'll try to meet your wishes, there might be instances where changes (dare I say concessions?) will result in significant cost savings.

    Boilers are very frequently oversized and can deal with heating additinal area. Only a well-conducted heat loss will tell for sure. Depending on the type and nature of your system moving radiators can vary quite easy to very difficult.

    If you're planning on extensive renovations, you may well want to consider devoting a reasonable portion of your budget to a thorough updating of your system--including the boiler. If you have standing iron radiators and an older boiler, the addition of thermostatic radiator valves (TRVs) and a modern condensing/modulating boiler. Your comfort and versatility will be exceptional while your fuel bills plummet.

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