Drayton MA1 not returning under spring pressure, but...

[Johnmdc]

Is the boiler in a garage? Do you have a frost thermostat? Maybe it was cold enough last night for that to fire your boiler up.

 

[Chris_c81]

Is the boiler in a garage? Do you have a frost thermostat? Maybe it was cold enough last night for that to fire your boiler up.

It is in the garage, I did think this, but it wasn't particularly cold, just wet.

 

[BarneyTheBear]

I have a similar problem any thoughts please? Everything runs fine as described previously in this thread; however, when the timer runs out and the controller is then off (set to both CH and HW) often, a fault occurs, I believe in the MA1 valve, of course still in A position, where because the grey wire still has ‘HW Off’ signal at 240v, I get an internal feed of 194v on orange wire, which is enough to maintain the boiler and pump running (with no command from the controller or effect by changing the room stat), also I get an internal feed of 121v back on white wire. The boiler will be running until I isolate the system at the main supply, on reinstating the supply all works ok, and of course MA1 goes back by spring to B. So, when this occurs, I’ve found that rather than isolate (because I have to reprogram the old controller), if I just disconnect the ‘HW Off’ to the grey wire, MA1 goes back to B, reconnect and I’m good to go. I’m assuming that the fault is due to troublesome micro switches in the MA1, so will most likely change, any thoughts from those with experience of this failure mode would be much appreciated. Note: all electrical testing carried out in accordance with best safety practices as I’m an electrical engineer.