"Christian McArdle" wrote in message
t...
I've read most of the condensing boiler discussions in this group and as
a
result decided to fit a standard boiler - mainly because of not being
able
to upgrade old radiators to work with the lower return temperature.

Unfortunately, you are misinformed.

Possibly.

Although condensing boilers can take
additional advantage of lower return temperatures, they are still more
efficient than a traditional boiler at high return temperatures too.


But there efficiency drops as the return temperature goes up.
And efficiency alters the time to repay - so with an old installation it
might make a difference.

What if they put the heat exchanger on the return flow?
That would drop the return temperature even if the old radiators didn't.
Am I being too simple minded?

This heat exchanger should be connected between flow and return as normal
via a zone valve.

Thanks for the reply - but why wouldn't it improve the efficiency to put it
in the return.
mikej