In an earlier contribution to this discussion,
Stephen wrote:

On Sun, 10 Aug 2008 19:13:37 +0100, "Roger Mills"
wrote:

Adding up the ratings of the radiators is putting the cart before
the horse. You need to start by working out the heat losses for each
room, and *then* choose suitable radiators for each room. The boiler
needs to have sufficient capacity to meet the total heat loss, plus
some for pipe losses, plus some for transient conditions (getting
the house up to temperature from cold, fairly quickly) plus some for
hot water.

Sorry, perhaps I should have made myself clearer. I used one of the
online calculators which asks for room size, whether it's north
facing, if it is double glazed, etc. and told me the radiator size
that room requires. It was those figures I have added up. Whether the
radiators that are in the rooms match those figures is another matter!
They were here when I moved in.

I'll check out the web sites you suggested. Thank you.

The on-line calculators I've seen are pretty crude, and only give ball-park
figures. You need one of the programs which you can download and run on your
own computer. These take proper account of wall construction, glass areas,
floor and ceiling losses, temperature in adjoining rooms, etc., air changes,
etc. - and give a much more accurate heat-loss figure.

You can download the Barlo program from
http://www.heatweb.com/programs/heatloss.html

The link which I have for the Myson program appears to be broken but, if you
ask nicely, Andy Hall will probably email a copy to you.
--
Cheers,
Roger
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