Can I fix my Mid Position Actuator Valve?

MrsBish · 27 Jul 2009

Hi,

I have managed to ascertain from this fab forum that we have a problem with our actuator valve.

In short, our heating comes on when we only want the hot water to come on. Have had a look at the valve and it seems to be stuck in the middle on 'M' and happily moves over to 'H' when I put the heating on, but it doesn't want to go to 'W' which I presume is where it should be if I just want the hot water on?

Is there much I can do to fix this. I know next to nothing about electrics and plumbing - although I have learnt lots while trying to diagnose this problem!! Do I just need to get an engineer in to fix/replace it?

Many thanks in advance

mickyg · 27 Jul 2009

Sounds like its the body thats sticking. What make of valve is it?

MrsBish · 27 Jul 2009

Can't see a make on it, it just says

Mid Position Actuator Code
BGMVSP-23
Followed by a load of technical data

Have tried to push the lever over to 'W', but it doesn't seem to want to move and I don't want to brake it.

mickyg · 27 Jul 2009

sounds like an BG branded ACL/drayton valve , assuming its blue.
Just to be sure its the valve, turn the power off to the whole system, the valve should spring back to hw, if it doesn't its definately stuck. If you feel confident you can remove the plastic cover(1 screw) and then remove the motor inside(2 screws), then check the lever now and see if it springs back to hw. If it does, you just need a new motor, if not the body needs replacing in which case you may aswell buy a whole new valve, as alot of the earlier acl ones you can't seperate the head/body.

MrsBish · 27 Jul 2009

sorry to be dim - but how do i turn the power off? it seems to be wired into a junction box which goes into something else? or can i just turn it off at the control panel in the kitchen - am not sure that that will cut power to the valve though.

D_Hailsham · 27 Jul 2009

MrsBish said:
it seems to be wired into a junction box which goes into something else? or can i just turn it off at the control panel in the kitchen - am not sure that that will cut power to the valve though.

What do you mean by the "control panel"? Are you talking about the programmer/timeswitch? If so that's not what you need to turn off.

There should be either a fused spur which supplied power to the complete heating system or it may be fed from a plug and socket on the wall. Unplug or remove the fuse from the spur. The valve will then reset and the indicator go to W.

Move the lever on the end of the valve to the other end of the slot. You should feel some resistance (opening against a spring). When you let go the lever should move back. If no resistance - lever loose, the valve is stuck in HW or mid position. You may be able to remove the actuator(box on top) and free the valve spindle with a small amount of WD40 or 3-in-1.

MrsBish · 28 Jul 2009

I think I'm going to have to get someone in to look at it.

The power cable goes into a Motherwell box on the wall, which states that the power should be isolated before removing the cover.

Have called a couple of engineers.

Do you have a idea how much a replacement valve should cost, so that I can guage if the costs given by the engineers are reasonable?

Many thanks for all your help.

D_Hailsham · 28 Jul 2009

Valve prices vary considerably. You can buy the Honeywell V4073A for anything between £45 and £75 online. The actuator, if only that has to be replaced, can cost as much as £55!.

If it's just the actuator which needs replacing, that's a simple one hour job - incuding diagnosing the cause of the problem. But if the complete valve has to be replaced, then the system will have to be drained down. The system will then need to be refilled with fresh corrosion inhibitor. The whole job could take at least half a day.

With some older valves, you have to replace the complete valve, even if it's just the actuator which is faulty. On modern vaves you can replace the actuator on its own.

RobbieR · 13 Dec 2014

Too late to help the original enquirer but should anyone else have difficulties with this valve maybe the following will assist. I experienced exactly the same issues and have spent a frustrating 48 hours trying to resolve the issue, hot water OK but heating only available when the hot water is in demand. Basic tests soon isolated the problem to the Mid-Valve, initially it was suspected the cable had suffered a stress fracture which made operation intermittent. This was replaced but the problem remained. Reading this column gave me confidence to remove the motor [after totally isolating the mains power] without ending up with a hand full of cogs and springs. I could now observe the operation of the mechanism and noted that the button on the auxilliary microswitch was not making due to play in the location of the pcb, when the pcb was pushed forward the microswitch would make. I replaced the motor and wedged the pcb forward with an off cut of eraser rubber - being careful to avoid the connectors carrying mains voltage. Problem solved - no thanks to Drayton and their poor quality product.

MelZuwider · 30 Dec 2014

Thanks Guys this was a great help and saved another DIY'r hours and many pounds today when it would have been hard to get someone out to look at it at all!

23 Degrees In and -4 Out....

ss2021 · 23 Nov 2022

get miniature 240v relay from CEF stock code 2625-5620.
put in the heating wiring across the pump feed relay connections a1-a2 across the pump L-N, the contacts in the 11-14 between the HW satisfied line from cylinder stat,time clock and the MPV grey wire.
this will cause the MPV to return to the HW position once the pump stops as it kills the HW satisfied too the MPV and prevents the valve from getting jammed in the HT position.
it does work as i did on my system years ago and i have not had any more problems with the MPV since

Alec_t · 23 Nov 2022

@ss2021 The thread you are posting in is 8 years old !
Welcome to DIYnot.

Harry Bloomfield · 23 Nov 2022

Happy thread resurrection!

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Can I fix my Mid Position Actuator Valve?

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