On Thu, 14 Aug 2003 17:12:44 +0100, "Christian McArdle"
wrote:

When designing an installation, with radiators sized for a flow temperature
of 70oC with a return differential of 20oC, you may permit the use of
smaller pipe diameters for the heating circuits.

In any case 22mm will be quite enough. There won't be any saving to had
downsizing to 15mm and I'm happy with 22mm rather than 28mm as it will fit a
pipe bender. I haven't calculated the radiator powers yet, so don't know if
70/50 will be doable in reality. They look to be on the small side to my
eye.

Christian.


Christian

The one to watch out for is not to drop from 22mm to 15mm too early,
in the sense of having too many radiators (actually too much capacity)
on 15mm runs.

If you are going to derate for 70/50 operation vs. 82/70, in general
it means dividing the required power level for the room by 0.6 rather
than 0.89 for most radiators, and then referring to the main table in
the manufacturer's data sheet to choose the radiators.

I found that when I refurbished my system, in some cases the radiators
were way oversized anyway so nothing to do, in some cases I moved
radiators from one room to another and in some cases I fitted new
radiators. However, there was only one case where I had to use a
radiator that had a larger footprint of wall space (if you follow my
meaning). For the others, it was possible to use a double panel or a
finned radiator where a lesser one had previously been.




..andy

To email, substitute .nospam with .gl