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How do you know what size boiler you need?

  • 06-08-2022 8:19pm
    Registered Users Posts: 8,863 ✭✭✭


    We are getting 60 square metres, two story extension

    Builder is saying we could try use existing boiler but he highly recommends not to as the size of house is increasing too much.

    Is there a mathematical thing I can do to check this:

    e.g. for so many square metres, rad's you need X boiler and for another set you need Y boiler?

    Post edited by DOCARCH on


  • Moderators, Home & Garden Moderators Posts: 10,123 Mod ✭✭✭✭BryanF

    It tends to be a bit more complicated than this ..

    has the engineer or builder offered this calc?

    normally you’d decide this early on

  • Moderators, Business & Finance Moderators, Motoring & Transport Moderators, Society & Culture Moderators Posts: 64,268 Mod ✭✭✭✭L1011

    Floor area and number of radiators are the main factors. The boiler model and size are critical in any calculation

    It is possible that an existing boiler can have its output changed in software to increase it; but this is not that common and could reduce the service life of the boiler.

  • Moderators, Home & Garden Moderators, Science, Health & Environment Moderators Posts: 17,110 Mod ✭✭✭✭DOCARCH

    Mod Note: @Tim Robbins I can move this thread to Plumbing & Heating if you wish? May be more suitable there?

  • Registered Users Posts: 8,863 ✭✭✭Tim Robbins