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Andrew Smith
Andrew Smith, Plumber
Category: Plumbing
Satisfied Customers: 3633
Experience:  City and Guilds qualified plumber
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I'm trying to work out the BTU requirements of my home in order

Resolved Question:

I'm trying to work out the BTU requirements of my home in order to replace current radiators. The online calculators give different results? plus i'm unsure of how to work out what BTU difference is for example between a room with a heated room above and below or a room on the ground floor that has a suspended un insulated wooden floor below and a heated room above. And will it make a difference if this void is insulated or not?
Submitted: 2 years ago.
Category: Plumbing
Expert:  Andrew Smith replied 2 years ago.
***** ***** : Best to work out the kW rating for each room with no heat gain from above or below, this will give worst case scenario
***** ***** : Bigger rads means you can run your boiler at a lower temperature save money and still heat the room
***** ***** : The bigger the better and then just use a thermostatic radiator valve to shut off the heat once the room reaches temperature
Customer:

ok... the problem is that the btu output of our new boiler is around 80,000 but but when we calculate the btu of the rooms (total) choosing the next rads up from the btu calcs online this exceeds the boiler output. The boiler is capable of heating our home ok since it does so now with the old radiators. essentially I want to make sure that if necessary the boiler and rads can work at max without damaging the boiler or being underpowered. if the btu of the rad is higher than that needed for the room then we can set a lower temp on the trv to compensate. however don't want to oversize the rad too much incase we need them all working a max and the boiler can't cope

***** ***** : You can fit whatever rads you need to heat your house
***** ***** : If the heat output exceeds the heat output of the rads then you will find the boiler take longer to heat to temperature
***** ***** : and may not reach full temperature until some other radiators start shutting down once the temperature is reached
***** ***** : If you have a standard boiler (with cylinder) then you should allow 20,000 Btu for hot water heating also
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