Central heating timer...

[geoff]

In message , Matthew Ames writes

I'll look on monday

[Roger Mills]

Except that it's a pumped HW circuit with a separate pump from that used for the CH - so there may or may not be gravity circulation when the pump's not running.

What's pretty certain is that there's no boiler interlock - so the boiler will be cycling on its own stat whenever the timer is on even if all demands are satisfied. Presumably the boiler doesn't mind not having any flow through it - which will be the case when the HW pump is off and the CH valves closed.

[Matthew Ames]

Thanks Geoff

[Ed Sirett]

Yes the controls could be implemented that way on an old cast iron (high water content) boiler. I'd be interested to know if such an arrangement was ever acceptable to the manufacturers.