Drayton 3 port valve - confirmation of fault?

[alanl]

Called out to newly installed boiler, using the old Drayton MA1 3 port valve.
When HW is on, CH is also on.
Checked all connections/wiring, all seemed connected correctly.
But, getting voltage at the white cable (HW on) at the valve.
Clearly something wrong there, as there should be no voltage unless CH is calling.

So, long story short, 'HW on' cable was not live when disconnected from valve.
But white wire was live, clearly getting a back-feed from somewhere.

Before I go and order a new actuator, I'd like confirmation that it is likely to be a faulty microswitch on the valve causing this fault, or have I missed something?

Thanks
Alan.

 

[jaydee81]

Are u sure it's wired correctly as heating on should be white hot water off is grey and hot water on is orange

 

[alanl]

Yes, that is my point, white is live, when it is not connected to anything.

Checked the feed to white, (disconnected from white) and it is live when calling, dead when not.
So that is correct.
Voltage is getting to white from inside the valve, I suspect a faulty microswitch, or faulty circuit board.

 

[alanl]

As a follow up, yes, it was a faulty actuator.
I havent had time to take the old one apart yet, but I suspect a faulty microswitch inside it.

 

[Doomed]

Don't forget that if the valve is in the 'manual' position mid position) you will get feed back through the switch if hot water is called for and heating is not.

 

[alanl]

I've since took it apart, and found the micro switch was jammed down, meaning the CH would always be on when there was power to the valve.