Good afternoon all,

for a particular application I am looking for a combined central heating
digital timer-controller/thermostat unit (wall-mounted), preferably
mains-powered although I would consider one of those handy roving
battery-powered ones if necessary...

My question relates to the wiring of the output switch. Traditionally a
central heating controller has a SPDT switch providing both a "CH on"
and "CH off" signal, and the pole of the switch is usually wired to
live, to provide the mains supply to the zone valve, and so on.

However, I need to find a unit specifically in which the pole of the
switch (and it must be SPDT, SPST) is not hard-wired to Live, such that
I can wire it to something else.

Does anyone who has fitted such a unit recently know if it is usual for
the manufacturers to hard-wire the switch pole to Live? Obviously for
the battery-powered ones this isn't an issue but for the mains-powered
controllers there is the possibility that the live power for the unit
and the switch pole are connected internally, which scuppers my plans.

thanks,

Michael