Drayton MA-1 valve problem.

[heatservice]

Has your room thermostat got a live feed when you select CH on your programmer? if so does the switched live also become live when you turn the dial to maximum?

 

[stem]

Just reread my last post and it's a bit wordy. So to simplify, here's a sketch explaining what I think could be the problem.

Has your room thermostat got a live feed when you select CH on your programmer? if so does the switched live also become live when you turn the dial to maximum?

If the live from the programmer / thermostat was missing, the valve wouldn't move over from the 'Mid' to the 'CH' position.

 

[skywatch99]

@stem -

Yes, the white wire DOES NOT connect to the motor live connector when the microswitch is 'at rest' (powered off). When the switch is depressed it DOES then connect the Grey wire to the motor live.

The motor has 2 orange wires for power (L&N) so that is what I was referring to when I said orange wires (not the orange wire that goes off to the boiler). Sorry for any confusion!

So it seems that this switch is at fault and the one on the old board is exactly the same, so I can't even scavange that! I do have a close match with just slightly larger terminals and can make this work if I can get the pcb out without damage.

Thanks - you helped a lot!

 

[skywatch99]

Your sketch matches my conclusion exactly.

 

[stem]

Unfortunately, I have never changed a microswitch, only motors. At this point I usually change the valve / valve head. You could try someone like RS Components, I used to use them, or Maplin for electrical components but Maplin have ceased trading now now.

Pity you don't know anyone with a broken valve you could cannibalise. It's not that common for the microswitches to fail.

 

[skywatch99]

Well I seem to have 2 with the same switch problem.....

I have a switch that will do the job, I just need to get the pcb out without damaging anything (hate to pay £55-75 when a £1.00 switch will fix it).

Something seems to be holding the pcb in position, I can lift both ends but always something in the middle is holding it down and I can't see what it is - I will keep trying though.

 

[Hot&Cold]

might aswell purchase a new actuator & valve if the new actuator goes on fire you can claim against the seller.If a diy self repaired actuator goes on fire your homeless .

sounds shytte but its true and there is case history.

There are a few component re manufactures around,most work to internationally recognised standards.

 

[heatservice]

BES do a Honeywell clone (Pt No:17391)for under £30 inc think Plumb Ctr & City Plumbing do them also.

 

[heatservice]

Looks like the drinks are on me, my money was on the motor

 

[skywatch99]

I have the pcb out now - on with the repair!

 

[stem]

Well I seem to have 2 with the same switch problem.....

In that case, why didn't you spot the fault immediately, as you have already come across it before?

Maybe it's just a Drayton issue, my comment about the microswitches failing referred to motorised valves of all denominations. Personally I prefer Honeywell, I know they are a bit more expensive, but I think they are worth it. My mothers bungalow still has an original 2 Port Honeywell valve in operation that was installed when it was built in 1981...... doesn't have a microswitch in it though.

Although, I suppose because valve motors are exchanged now, so extending the valves life, failures of microswitches will also become more common as they will be in service for longer.

 

[heatservice]

In that case, why didn't you spot the fault immediately, as you have already come across it before?

Maybe it's just a Drayton issue, my comment about the microswitches failing referred to motorised valves of all denominations. Personally I prefer Honeywell, I know they are a bit more expensive, but I think they are worth it. My mothers bungalow still has an original 2 Port Honeywell valve in operation that was installed when it was built in 1981...... doesn't have a microswitch in it though.

Although, I suppose because valve motors are exchanged now, so extending the valves life, failures of microswitches will also become more common as they will be in service for longer.

So so right Stem, as I said earlier in this post "Planned Obsolesance" the older they are the better,some others no longer have any vents to let the heat escape, Honeywell's cover being metal dissipates the heat somewhat. while Danfoss just cook their motors in an almost airtight box.

 

[skywatch99]

@stem - The old one was not a switch problem as I remember other than leaking water and tripping the breaker - could have been bad.

@heatservice - I wonder about that too - maybe drill some small vent holes one day .....

As for today - all done and finished.

Working as expected.

I had to use a new microswitch from my parts bin that had a lever and roller on it (a pair of pliers got those off in seconds) - Then tested it and it was the right size, shape, and rating to do the job - only problem was it has 'lugs' and not 'pins' to go throught the pcb. 30 Minutes later the holes were filed to accept the new switch. Everything got a good clean, new switch soldered in and so far working as advertised!

Not a job for the faint-hearted, but with the right experience and qualifications it was straightforward. At least it has bought me some time to think about replacing the head if I get another problem with it.

Thanks to all for the help on this, it will be warm here tonight I hope