On 9 Nov 2003 11:06:34 -0800, (bodger) wrote:

Hi. Our old Rayburn multifuel cooker/boiler just died, and I need to
replace it with something else. The rayburn used to run a central
heating system of 13 radiators with a total area of approx 12 square
yds; 9.6 square metres.

Can anyone tell me what Btu output figure the replacement stove should
have to run the existing radiators comfortably? Or where on the web I
could find the formula to work it out for myself?!

Many thanks.


The first thing is to dump the idea of Btus. They are a deprecated
unit and make calculation harder. Working in metric units and watts
is very much easier.

Take a look at the web sites of the radiator manufacturers such as
Myson, Stelrad and Barlo and find radiators of similar type and size
to those that you have. Take care to look at whether they are double
or single panel and with or without fins. This makes a big
difference to output. Once you have the sizes and types, look up
the output in Watts from the data sheet. For a standard convention
al boiler operating with 82 degree flow temperature, multiply the
figure in the table by 0.9 because the output and heat requirement
will be lower than the test temperature.

Add these and add about 20% for margin. If you are replacing with
another Rayburn, then you can find the specifications on Aga Rayburn's
web site. If you are considering a wall or floor mount boiler then
a condensing model is a good plan because of increased efficiency.
Many of these types as well as conventional boilers modulate the
burner and so will match output to the requirement, so getting the
sizin g perfect becomes less of an issue anyway



..andy

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