bassanclan Posted November 24, 2016 Share Posted November 24, 2016 Any recommendations for an accurate/good radiator sizing website. I've put the details for one room into three different websites and the results range from 8800 to 12000 BTU! Link to comment Share on other sites More sharing options...
PeterW Posted November 24, 2016 Share Posted November 24, 2016 This one and subtract 15% seems to be about right for me most times https://www.traderadiators.com/acatalog/heating-calculator.html Link to comment Share on other sites More sharing options...
bassanclan Posted November 24, 2016 Author Share Posted November 24, 2016 Thank you. It has given me a figure of 9592 BTU - 15% = 8153 BTU I think if I go for 9000BTU I should be right in the middle of all these calculations, the 12000 BTU is an outlier. Link to comment Share on other sites More sharing options...
PeterW Posted November 24, 2016 Share Posted November 24, 2016 Just watch the sizing as they assume a wall of 0.3 on the uValue and not the much better standards you're probably building to. Link to comment Share on other sites More sharing options...
bassanclan Posted November 24, 2016 Author Share Posted November 24, 2016 It's a refurb with a wall of 280mm - insulated cavity of 80mm, so probably worse than the assumptions! Link to comment Share on other sites More sharing options...
JohnW Posted December 7, 2018 Share Posted December 7, 2018 Just trying to resurrect this thread - I can't find an online radiator sizing calculator that accounts for triple glazed windows or really well insulated walls, floors & roof. Does anyone know of a reliable one that does? Link to comment Share on other sites More sharing options...
PeterW Posted December 7, 2018 Share Posted December 7, 2018 None do - they are a long way behind the times. What you need to do is work out your total load, check the room volumes and then size based on this. @JSHarris spreadsheet is a good start for this. Link to comment Share on other sites More sharing options...
JohnW Posted December 7, 2018 Share Posted December 7, 2018 Thanks @PeterW are you suggesting I use the spreadsheet to calculate the whole house heat loss and then if a rooms volume is 10% of the whole house volume then the heat loss for that room will be 10% of the total heat loss? Link to comment Share on other sites More sharing options...
PeterW Posted December 8, 2018 Share Posted December 8, 2018 It will be a reasonable start - you may need to flex it a little based on the external walls etc but if you oversize the rads you can turn them down Link to comment Share on other sites More sharing options...
CC45 Posted December 8, 2018 Share Posted December 8, 2018 I always try to see how the size of rad will look in the room. I increased the size of some of ours so they looked right. It is a very well insulated house so the rads were (and still are) on the small side anyway. If you are in any doubt then bring the pipes up in the centre of the rad and then go left and right - that way you can fit a bigger rad if you want to at a later date. Link to comment Share on other sites More sharing options...
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