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Posted 20 hours ago

Drayton 3 Port motorised Valve MA1 Actuator only.

£9.9£99Clearance
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ZTS2023
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At this point, demanding Hot Water causes the actuator to move to the W position and if the demand for Heating is still there, the actuator moves to the mid-position. (This is counter-intuitive to the problem of no hot water in the morning as when I test the system the actuator moves with hot-water demand even though it had not done so yesterday morning!) I have a really weird problem with a Drayton MA1 mid-position valve and I can't find any reference to this specific problem. As I said, when I turn the water on, the actuator does move to either the mid or W position depending on whether there is demand for Heating as well. In that respect it all works perfectly. I turned off the power to the system and immediately the actuator returned to the relaxed, Water, position under spring pressure. As my MPV position indicator is 'hidden' from view, I had never realised that the MPV stayed in the last position demanded by the system and concluded, wrongly, that I had found the cause of the cold shower; assuming that the MPV had not moved when demanded. I had always thought that the MPV only moved to the H position when heating was demanded.

Last night my partner heard a very strange buzzing whiring noise coming from what i now know is the "mid position actuator" . That was why I came here and my misunderstanding has now been corrected thanks to John and flameport! If the valve was previously at Heating only, the result is the valve being held in that position, so finding the valve at H with no demand after using the heating is normal operation and exactly what you would expect.Boosted HW MPV stays in W. Boosted CH and MPV moves to H. Turn the boosts off and MPV remains in H and after a short time pump stops.

With power applied to the white wire only, it will move to the mid position for hot water and heating. formatting link When there is a HW demand but not a CH demand, the valve is un-powered and sits in the HW position. The boiler and pump are powered directly from the cylinder stat. 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. So, it seems as though everything is working normally until there is a demand for Heating only, when, once it is satisfied, the actuator remains in H. This is repeatable! 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.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. The best advice I got was that my system was working as it should and I am glad to say it is. From those who knew, I learned what it is that holds the MPV in the H position even when there is no demand for heating, the HW-OFF feed from the programmer. 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. However, turning off the system power causes the actuator to return immediately to the W, relaxed, position under spring pressure. Turn on the system power and everything works as it should, until the Heating-only demand is satisfied when the actuator remains in H.

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. 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. 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. The system is a conventional gravity-fed system with gas condensing boiler, Lifestyle LP522 programmer, Drayton RTS1 room-stat, Honeywell tank-stat, Drayton MA1 MPV and ACL Lifestyle Wiring Centre.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. The problem with the cold shower remains a mystery, appears to be a one-off and it has not happened again. Edit: I've just done some more investigating this morning. The problem of the pump continuing to run last night, doesn't appear to occur when I try it now. I unplugged the MPV and it caused the pump to switch off and the valve return to its default W.

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