Nigel Frost wrote:
Thanks for all your help - very useful indeed.
It seems that a separate zone, with it's own controller, is the way to
go.
I'm a bit wary of the systems with only a thermostat on the return
path, as the water entering the UFH pipe will be hot!
Other systems I've seen advertised on the web have a CW blending valve,
room thermostat, and a pump. I'm curious as to why the UFH needs its
own pump, when the boiler has a perfectly good one.

Thats because of the temp reduction thing. You want to be still pumping
hot water around even when the boiler has cut off...and the blending
valve may have more or less isolated you from the CH main circuit.

Also the CH pump will not work efficiently when the blending valve has
almost shut off the flow and is in 'recirculate' mode.

The ideal for UFH is moderately warm water flowing fairly fast through
so that there is little temp differential between flow and return,
otherwise you get uneven floor heating and possible cracking.

Whereas normal CH is piping hot flow, and cold return.

I can't see the point of a a thermo on the return path either. Its the
forward path that needs to be prevented from getting to hot,and a
packaged pump/manifold/blending valve/motorised valve like wot polyplumb
do is a really good way to go.

It made installation for mine a complete snap. And the little flow
meters on the manifold are a boon when setting up and balancing.


Nigel Frost