Andy Hall wrote:
On Mon, 07 Mar 2005 19:57:26 GMT, Bedouin
wrote:


Christian McArdle wrote:

A house needing 22kW suggests to me that it's either large or has poor
insulation because it's older and you can't put insulation in enough
places to make a big difference. If that's the situation, then it's
more important to look at heat loss because you will have little to
address the variations during a day. The temperature will change
quite quickly with the outside temperature. If you have a situation
where the insulation is better, there will be less intra-day
temperature change and so you don't have as much sensitivity to sudden
weather changes.

That's certainly true - it has comparatively large surface area - being
L shaped, and as a solid walled 1920 construction there is no easy way
to improve the insulation further without major work. The low power of
the boiler, and the comparatively high thermal mass of the house, means
that it is very slow to warm up in cold weather - hence the desire for
considerable more power.

There's no magic way, unfortunately. If you are concerned, and the
house is not well insulated, then I would go for higher power. This
will cost more, but not as much as getting it wrong and having to
replace the boiler with a larger one......

That's my feeling too - but the range of boilers in the 35-40kW size is
obviously lower than in the more common 28kW area.