Hi

I've been having problems with the central heating where the rads are
coming on when the boiler is intended to be only heating the water. I
immediately assumed there was something wrong with the mid-position
valve.

It is a drayton MA1, where the actuator push-fits onto the valve
assemble.

Examination of the actuator revealed rattling parts inside and opening
it up I have discovered that the plastic nodule holding one of the
return springs has broken, so clearly there was not enough force for
the mid-position valve to be brought back to the HW only position.

Ordered a new actuator which arrived at the weekend.

I pushed it into place a wired exactly as it was before, but this
doesnt seem to be working at all - always seems stuck in mid-position.

Does anyone know anything about these MA1 actuators? There is a black
button at the end of the assembly which sticks out on the old (broken)
actuator, but is pushed in on the new one. Does this have to be
released in order for the actuator to run freely between its three
positions? I gently tried to turn the actuator by using a screwdriver
in the valve hole, but it is stuck.

thanks
Nigel