Re: Manifold/TRV actuators - 24V or 240V?

["simon_haslam" <simon_haslam@xxxxxxxxxxx>]

Thanks for all your replies to this question - here's a summary for anyone
else pondering the same question.

I've decided to go with 24V 4-wire actuators although the decision was very
finely balanced and I'm sure either would have done fine. The
considerations from your various comments were:
* reducing the amount of 240V connections where possible makes sense
* 24V on the continent.. probably suggests it will become more prevalent
over here over time
* 24V transformer power loss - there will probably be more efficient PSUs
in a few years (though really we're talking negligible amounts of energy
really when compared to the boiler). Depending on how it is ultimately
wired up I could always switch off the transformer when the boiler was not
in use, though I suspect with a full HA set-up you'll get a chicken and egg
situation (i.e. need zone valves to open, to supply demand to boiler and
switch power on to zone valves... doh!)

My current thinking is to have 7 of the relays switching in the 24V
actuators, and using the aux switches on the actuators to drive the 240V
demand line on the boiler (as this is how my regular CH programmer works).
The wires from the actuators will be terminated in a separate box (i.e.
240V) and then only the 24V feeds for them will loop down to the I/O box.
If I can find out from Viessmann how to switch on the boiler at low voltage
(emulate one of their controls) I'll do that instead.



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