"IMM" wrote in message
...

"John Aston" wrote in message
.. .

If anyone else is reading this thread and wants some background
information,
I came across Warmrite's "Manual Of Modern Hydronics" at
http://www.heatinghelp.com/pdfs/156.pdf

It gives loads of examples of different boiler/heating arrangements.

I had a look. The document is specific to UFH and the USA/Canada
variantions
and heavily leans towards the makers solutions. Look at figs. 2.1,
regular
boiler & 2.2, condensing boiler. Condensing biolers should not mix return
water that woudl raise its temperature. That is why a thermal store/heat
bank is the best alternative when using a condesning boiler, which is what
I
have been trying to get you to understand.


Sorry if I've missed the point about a heat store.

I've spoken to technical engineers at Keston, Viessman, MAN Heiztechnik and
Geminox, and they have all recommended that a low loss header should be used
for my application. It's difficult to argue against that weight of opinion.;