Drayton 3 Port motorised Valve MA1 Actuator only.

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Very frustrating and don't know what else to do with the damn things other than to have a different make and model installed. I don't do it myself. I get a professional to do it - thank god I have an all-singing-all-dancing central heating insurance cover to deal with it. If the boiler doesn't run when there is *only* a CH demand, it indicates either that the valve hasn't moved all the way to the CH position or that the microswitch isn't working.

The problem I am having though is even after the temperature set by thermostat has been reached, and after the scheduled CH OFF, my pump continues to operate, my radiators continue to heat and the temperature continues to increase. I was ready to go buy a new actuator as I believed this was the problem, however it appears to operate as described in the above discussion. The system has been working perfectly for 14 years until yesterday when the domestic hot water was cold. That is, there is a shared (flow) valve which has to open to allow any water to flow, then a second 3 way valve which decides which way the water will flow.

I do know they have a circuit board and very flimsy, but normally reliable, micro-switches but why would I want to go replacing the whole actuator, as you suggested in the first place, or even the circuit board as you now suggest, when the excellent descriptions of correct operation given by both 'Jonhmdc' and 'flameport' show that my actuator was working correctly all along and the only thing at fault was my understanding of its correct operation.

From what you say, does the actuator stay in the H position when the demand is satisfied when the timer is still on (as well as when the timer shuts off) and if so, what is keeping it 'actuated' there and thus stopping the spring pressure from returning it to the W position? That was why I came here and my misunderstanding has now been corrected thanks to John and flameport! When there is a CH demand but no HW demand (tank stat satisfied or HW off at programmer) the valve moves to the CH position. A microswitch in the valve actuator switches a live supply to the orange wire - which then powers the boiler and pump. Last night my partner heard a very strange buzzing whiring noise coming from what i now know is the "mid position actuator" .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.

The manual lever only moves the valve to the mid position, and is useful when filling or bleeding the system to make sure that all water paths are open. It will flop around when the valve is powered to the mid position or beyond - this is normal.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.

Anyway having diagnosed this far I'm going to leave it with the central heating and the water heating on full time to see if I can get the temperature in the bungalow up to the expected level.For some reason later in the day, with the hot water off and the heating on, twiddling the thermostat does not cause the boiler to fire and the pump to run; I assume causing the pump to run is the critical test because the boiler usually fires a bit after the pump runs. I have a really weird problem with a Drayton MA1 mid-position valve and I can't find any reference to this specific problem. With the head unit removed from the valve body, turning on the system and demanding Heating causes the actuator to move to the H position. Turning down the room stat satisfies the demand and the system shuts down the boiler and the pump but the actuator remains in the H position. Cycling the demand fires the boiler and pump but satisfying the demand with the room-stat has no effect on the actuator which stubbornly remains in H. Given that, if the flow valve is permanently open and the 3 way switch is in the middle then water should always flow around the central heating. The MPV actuator is a BGMVSP-23. The control and thermostat is a Hive system. Boiler is a Worcester Greenstar Ri. System is gravity fed open vented system, tanks in the loft and HW cylinder in airing cupboard.