On 5 Oct, 23:13, Dicko1 wrote:
I've got an intermittent problem with a Honeywell V4043 motorised
valve. The grey wire into the unit is always live but the orange wire
never gets live when the timer unit switches on. Net result is that
the heating zone doesn't work unless on manual.

On the basis of the above, I'm assuming that the internal switch has
gone rather than there being any problem with the synchro motor.

Does anybody know whether replacement switches can be sourced?

Or is my diagnosis potentially wrong?

Does the valve motor operate when the timer switches on? There could
be a motor failure, a thermostat failure or simply a break in the
connecting wiring somewhere along the route.