On Tue, 16 Dec 2003 17:32:02 -0000, "Christian McArdle"
wrote:

True, although a simple switch near the boiler connecting the
switched outputs from the room programmers would achieve the
same thing.

Better to supply the feed to the programmable room stats, rather than the
switched returns. Then you only need a SP switch for the lot, instead of a
pole per zone.

Christian.



No because they all come together at a common point at the boiler
anyway, to form the switched live to fire it up.

If you have two (or more) room programmers, you could bring their
demand signals and connect them together, then go through the switch,
bring in the HW demand and then into the boiler.

This is an "or" function of the room programmers followed by an "and"
created by the switch followed by an "or" with the HW.

Boiler = ((Prog1 OR Prog2 OR ...... ProgN) AND Switch) OR DHW



..andy

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