On 15/02/2011 10:15, Skipweasel wrote:
I currently have a Y plan heating layout.

I'd like to connect the conservatory UFH to it. The UHF has a
thermostatic valve in the return circuit and is situated some distance
(in terms of pipework at least) from the boiler.

Is there any obvious alternative to converting from Y plan to S-plus
plan (including a bypass for the boiler)? It's worth mentioning that the
UHF and heating are never expected to be on simultaneously, though the
system should be able to withstand it without damaging itself.


I can think of a way which *might* work - but you'd end up with a highly
*******ised system which future generations (or even the present one!)
might not be able to understand!

How about if you split the CH output from the 3-port valve into 2
circuits, with a 2-port zone valve in each - one for the radiators and
one for the UFH. Control these valves a bit like in an S-Plan system,
with the radiator one being controlled by the CH room stat and the UFH
one being controlled by a new? roomstat[1] in the conservatory.
Now the clever bit. . (I think!) Parallel the auxilliary contacts in
the 2-port valves, and connect them into the circuit where the Y-Plan's
roomstat used to be.

That should give you independent control of the radiator-based and UFH
parts of the heating system, still with boiler interlock. However, you
still might need a bypass if the boiler needs pump over-run because
there would no longer be a guaranteed flow path.

[1] I assume that the UFH's thermostatic valve is mechanical rather than
electrical, otherwise you might be able to use that instead of an
additional room stat. If it *isn't* being used - either by my 'solution'
or if you go the full S+ Plan route, it's probably best got rid of.

--
Cheers,
Roger
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