problem with mid position valve? ?

Thanks for the helpful post. I followed this and found dirty contacts on one of the microswitches. I first tested the microswitch with the meter and found no continuity when the switch was closed. I was able to open the microswitch with a knife and clean the contacts with some wet and dry.

M Smith
April 2014

Just in case anyone else wants to know what my problem turned out to be this is what I did.

I replaced the valve motor with one from screw fix and had the exact same problem. So I took the circuit board out to see if anything had burned out. And discovered that both micro switches where faulty.

They both had very dirty contacts and one of them had a bent contact causing it to arc when energised. I cleaned them both up resoldered them to the circuit board plugged it all back together and its all working again.

For anyone with an acl-drayton 679H340-30LO valve, ie the old type without the removable actuator, it IS possible to completely disassemble it as follows;

TURN OFF ALL POWER TO THE CENTRAL HEATING IF YOUR NOT SURE HOW TO DO THIS YOU SHOULD NOT READ ANY FURTHER. CONTINUE AT YOUR OWN RISK.

1. Undo the screw and take off the cover.

2. to remove the motor there are two screws, ones probably hiding behind the orange wires. remove the screws and pull the motor away from the body with the earth plate and heatsink/cover then carefully unplug the connectors from the circuit board. If you need to replace the motor just plug and screw in your new one.

3. to remove the circuit board, slide off the white cover, and undo the two small screws that go through the micro switches. You can now remove the circuit board. (If you havent already you'll also need to remove the cable clip).

4. if you want to go any further, (I didnt), you can remove the actuator bits and springs and there are two screws to remove the actuator body from the valve body. And thats pretty much it.

Neale
November 2008