Drayton Mid Position Actuator MA1

David · 2018-12-24T23:45:16+00:00

Merry Christmas one and all.Staying in another house and there is an ancient and dodgy central heating system.The valve is a Drayton Mid Position Actuator MA1.It seems to have two functions; an open/close switch and a three position switch for Heat Mid and Water. I assume that the logic is roughly;If heating or water is called for the main valve opens and the 3 position valve moves to Heat or Water. If both are called for then the Mid position is selected which allows water to circulate to both.Digging so far indicates that if the controller calls for heating (with thermostat set above ambient temperature) nothing happens.If water is called for the main valve sometimes opens and the pump runs.There are manual overrides for both functions - valve and 3 way selector.I can (just about) get the cheap plastic piece of shit manual override on the main valve to stay open. The 3 way manual override plastic lever seems to be sticking out of the back of the valve housing - I can see the other end when I waggle it - so I can't move that valve around to see what happens.At the moment I am assuming that the valve is in the mid way position (otherwise we wouldn't be getting hot water from the tank and some heat from the radiators) and the strange behaviour of the heating is because it only works when the programmer for the hot water is on.Venting here to see if my conclusions seem reasonable.One side of the house, the radiators do get hot, Some of the other radiators don't, or at least take a long time (I've only recently put the hot water on constant). Pump is on flat out setting. This suggests that the radiators may not be balanced.Now some heat is getting to the cold radiators. The new (compared to the others) double radiator is doing something I haven't encountered before. The rear part is heating up but the front part is staying cold. It doesn't have air in because I have bled it (amazingly after a long search I found a bleed screw) and it was full of water.I assume if the 3...

Dec 24, 2018 Last reply: 7 years ago 21 Replies

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The Natural Philosopher 7 years ago

In generally if the motor moves them at all it moives all the way.

The hand lever IME will NOT open the valve enough to move the microswitch.

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John Rumm 7 years ago

I was referring to the specific case of dealing with failed microswitches.

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