honeywell V4043 MV microswitch replacement

[Dicko1]

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?

 

[D_Hailsham]

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.

The orange will only get live if the timer is ON and the room thermostat is calling for heat.

Have you tried all options on the timer, e.g constant, once timed etc.?

Have you tested or bypassed the room thermostat?

Can you hear the motor working when CH is called?

If NO, the motor may be burnt out.

Is the lever hard to move when CH is OFF and loose when CH is ON?

If always hard to move, the motor is burnt out or the gears have sheared

If always loose, the valve is sticking.

Does anybody know whether replacement switches can be sourced?

You could try Maplin. You will have to remove the existing switch and take it along to get a match. Otherwise you will need a replacement actuator (assuming the existing one has a small bump on the top) or a complete new valve.