3 port V4037A mid position honeywell valve

[ant101]

Hi

Is this a fault ?

white and orange wire from valve still show 240 v when CH is satisfied or turned off. The only way to stop this is to turn off at the mains or turn HW on.

I ve got a brief idea what is happening inside the valve but cannot grasp where the 240v is coming from. All I can think of is that it is coming from the grey wire (HW OFF) from microswitch in valve. But should this not be about 100V to orange only ?

Thanks in advance

 

[stem]

It sounds wrong to me. The white wire should only be live when the central heating programmer and room thermostat are calling for heat.

Caution is needed with the orange wire, because as well as becoming live when the valve winds fully across (central heating only position) it will also get a live on it, that is fed back from the cylinder thermostat when that's calling for heat.

There's a great animated diagram click here showing how the 'Y' plan works and which wires should be live when.