potterton mpe 222 motorised valve

[ssb1973]

Hi,

I think we may have a problem with our motorised valve (Potterton MPE222) for the central heating. Could someone please confirm if I'm correct.

The symptoms are, that our CH comes on even when the timer is switched off, and when the CH is even set to the OFF position on the timer, it still comes on. Whether the thermostat (Honeywell) is turned all the way up, or all the way down, the CH still stays on. The only way to turn the CH off, is to turn the temperature setting down on the Vaillant Thermocompact System boiler.

All our rads have TRVs except the one in the hallway where the stat is located, this rad seems to be on most of the time.

I've removed the Potterton MPE222 from the plate and pipe in the airing cupboard (electrics still connected), and tested the stat in the hallway.

When the stat is turned up and clicks, the MPE 222 spindle turns very slowly for a about 10 seconds and then goes off, when I turn the stat all the way down the motorised valve spindle spins very fast for a few seconds then stops. Is this normal behaviour, or do I need a new Potterton MPE 222 (or equivalent)?

Even with the MPE 222 motorised valve device now detached from the pipe the problem still exists, the heat still comes on even when the timer is switched off, and stat is on 0 degrees. Is this conclusively due to the faulty motorised valve.

If I were to turn the valve on the CH pipe in the airing cupboard manually with pliers to the close position, would this be a temporary workaround?

 

[twgas]

sounds like your heating valve, but needs testing.

1) turn off power
2) disconnect CH valve orange wire (in wiring centre) and make safe.
3) reinstate power.

if heating stops problem proved.

 

[D_Hailsham]

sounds like your heating valve, but needs testing.

2) disconnect CH valve orange wire (in wiring centre) and make safe.

Doing it that way leaves the orange wire live. It might be safer to disconnect the grey wire. Assuming the installer has connected the grey and orange wires the right way

 

[ChrisR]

Doesn't sound like the valve to me.

If the switch were faulty, the valve would still be closed so the heating wouldn't come on, though the boiler would cycle.
If the valve were sticking, the heating would never go off. Removing the head and seeing it move (correctly, by the way) shows the head isn't sticking. I think we can guess that the poster has tried turning the shaft on the valve body, and hasn't commented that it was stiff.

So unless the valve has multiple faults, it ain't that.

SOmething is opening the valve.

The room stat would normally get its power from the programmer, so they would BOTH have to be faulty.

Is there a frost stat?

I would though look at the connections to the valve as a start. WHen the heating's on but shouldn't be, what are the voltages on the blue, brown, grey and orange wires?

 

[twgas]

sounds like your heating valve, but needs testing.

2) disconnect CH valve orange wire (in wiring centre) and make safe.

Doing it that way leaves the orange wire live. It might be safer to disconnect the grey wire. Assuming the installer has connected the grey and orange wires the right way

of course you're right D_H, but in my defence I did say make it safe (see above, in bold)

 

[ssb1973]

Thanks for the input everyone, I've got a bit further with this.

If I turn the metal valve on the pipe manually with pliers to the horizonatal off position the burner on the Vaillant thermocompact system boiler goes off, and the status shows:

s 07 - water pump over run for a few minutes, then status changes to
s 00 no heating required, which is what I would expect in normal conditions.

If I turn the valve manually to the vertical on position with pliers the heating comes on as it should.

After investigating further, I took at look at the plastic part of the MPE 222 motorised valve where the metal valve goes in and spins. I observed it while turning the thermostat to on and off positions - when I turn the stat to on (~20 degrees C or more), the plastic bit in the MPE 222 valve spins, and ends in a vertical position. However, when I turn the stat off (below 20 degrees C. The valve motor spins, and the plastic bit returns to the vertical positions (on).

I think this is probably the essence of the problem. Is there any way of re-calibrating the plastic bit, (I have tried turning it with a screwdriver, and it doesn't turn), back to a horizontal position when the off signal is sent to it from the thermostat, or do I need a new motorised valve?(Potterton MPE 222).

Many thanks in advance.

 

[D_Hailsham]

Sounds like you need a new actuator.

http://www.heatingcontrolsonline.co.uk/potterton-myson-act222-actuator-mpe222-msv222-p-121.html

 

[ssb1973]

Many thanks,

Yes, it does look like I need to get a new actuator/MPE 222 (or maybe even a replacement motor?). How easy is it to replace the actuator by myself, with no experience of plumbing.

The Corgi man said it would cost, £100 for parts and labour inc. VAT.

What do you reckon.

 

[ChrisR]

If I turn the valve manually to the vertical on position with pliers the heating comes on as it should.

Er, worried, but OK...

when I turn the stat to on (~20 degrees C or more), the plastic bit in the MPE 222 valve spins, and ends in a vertical position.

That sounds right, then??

We've all asked...

WHen the heating's on but shouldn't be, what are the voltages on the blue, brown, grey and orange wires?

 

[ssb1973]

ChrisR.

I don't have the necessary tools to test the voltages on the wires.

The only thing I can use to troubleshoot at the moment is my eyes

Yes you're correct, when based on my observation I said that the plastic spindle in the motor spins slowly and the valve slot goes vertical when the stat is turned up - this is expected, as the valve is two way (vertical on, and horizontal off.)

When the stat is turned down, the motor spins fast and doesn't go to an off position (horizonatal slot). This I believe is the problem.

When I turn the valve on the pipe manually to on or off it works as expected i.e. radiators work perfectly, stat works properly, timers working, radiators turn on or off as they should..

If the motor and/or MPE 222 was working correctly, then when I turn the stat down, it should spin the motor to a horizontal position to close the valve, as demonstrated earlier when I turned the valve with pliers manually. But instead it's spinning it to a vertical position instead (leaving the valve open, hence the heat continues to stay on).

Therefore, is it easy to replace the motorised MPE 222, or the motor within? (Assuming based on other peoples opinion on the forum, that the issue lies conclusively with the MPE 222).

 

[D_Hailsham]

Therefore, is it easy to replace the motorised MPE 222, or the motor within?

When you remove the actuator - that's the box on the top - you can turn the valve shaft easily from open to closed?

If so, then all you need to replace is the actuator box, which costs about £35 and is a DIY job.

The actuator part no is ACT222

 

[ssb1973]

Yes, I can easily turn the valve using my fingers to on or off positions. The reason I used pliers earlier was because the valve was too hot.

So all I need to change is the actuator, ACT 222. If I buy a new one, then open the old one - disconnect the wires from the old one, and reconnect them to the new one respectively, and then put it back in the plate. Job done?

 

[D_Hailsham]

So all I need to change is the actuator, ACT 222. If I buy a new one, then open the old one - disconnect the wires from the old one, and reconnect them to the new one respectively, and then put it back in the plate. Job done?

There is no need to open the new actuator; it will come with four leads attached - brown, blue, grey and orange. Just disconnect one lead at a time of the old actuator at the other end and connect the same coloured lead from the new actuator to the same terminal.

 

[ssb1973]

Thanks for your help everyone, I bought an act222 actuator for around £34, and fitted it myself, all is working now normally.

 

[kieran5405]

Hi,

Just a quick question...I am in the same position of replacing this actuator. I am a total newbie but i have read the instructions for the actuator etc...

My question is in relation to replacing the wires one at a time. To do this what did you turn off...I presume the electricity in some area of the house must be turned off. But not sure where...is there something specific you shut down.

Thanks...