Andy Hall wrote:
On Thu, 30 Dec 2004 23:20:20 +0000, Dave
wrote:

.... snipped

Are you going for a condensing boiler? If so, you can design the
radiator provision around a 70 degree flow and 50 return. This will
keep the boiler at the efficient end of the scale and also give you
plenty of head room for very cold weather. It does imply larger
radiators of course. Don't forget the correction factors from the
manufacturer data tables. These are normally 0.89 for 82/70 degree
operation and 0.6 for 70/50.


I can size the rads for a 70 flow but can't see how to achieve a 50
return. If the house is heating from cold (and all TRVs are open) the
return will presumably be much cooler than when the house is up to
temperature and all/most TRVs shut; is it really possible to design for
a specific return temperature?

--
Dave S
(The return email address is a dummy)