Doctor Evil wrote:

90% plus of systems are designed to have radiators run with an 80C flow
and 70C return. You can design the system to have 60-40C. Obviously the
rads will be larger. But the lower temperature operation ensures high
efficiency from a condensing boiler. Condensing boilers are more
efficient the lower the return temperature. They can operate at a 20C
flow/return temperaure differential, as opposed to 10C on a
non-condensing boiler.

The manufacturers have tables to work out the rad size on 70-50, 60-40.

Thanks Doctor Evil.
I'll check it out.


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