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EDR for given room size

Anyone with a link to a calculator or chart I can fill out to let me know the approx. EDR required for a room? I have an existing radiator that leaks and needs to come out (so I can repair the rotted floor beneath) at the same time I want to bump the size up a bit. The room was renovated (made bigger) years ago and the existing radiator was not upgraded. Hopefully the boiler can keep up but it shouldn't need to be much bigger...

Got a link / chart / method for relating radiator EDR to room size/windows etc?




  • KC_Jones
    KC_Jones Member Posts: 5,081
    You need to do a heatloss calculation on the room. Get the BTU number and divide by 240 and that will give you EDR. The heatloss is the only way to do it correctly. Slantfin has on on their website you can use on a tablet or smartphone.

    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
  • srmaietta
    srmaietta Member Posts: 33
    Thank you gentlemen.

    I'll get an estimate for the room heat loss and see how the current radiator stacks up.

    Also, Ill compare the heat loss calcs of some of the other rooms to their radiators and see what the average works out to be. May shed a bit of light on the overall balance of the house..