Faulty Mid-Position Valve??

Okay, after browsing the forums I think my mid-postion valve is faulty, but I wanted to check before deciding what to do next. The symptoms are...

- CH comes on when only HW is selected (i.e. I cannot turn my hot water on without the rads getting hot). HW also comes on when CH is on, but I think that is normal, and how it's always worked.
- Thermostat is not working, so the rads just get hot, but the heating doesn't switch off when it reaches the required temperature (I'm a bit worried this may cost me a fortune in gas bills)

This has been the case since I returned from holiday a few weeks ago.

I've tried waggling the metal tag on the underside of the valve to no effect. The black switch on the right hand side of the valve feels fairly loose, although if I push it upwards there is some resistance (and a tiny whirring noise). I'm not sure what position this switch should be in, but I've tried having it at the top and bottom and the CH still doesn't work properly. I've also tried switching the CH/HW on and off while watching the switch and it doesn't appear to move.

Do I need to replace the whole valve? If so, how easy is it, and can it be done "dry" or do I need to drain the system?

Any help would be appreciated. I've attached a pic of the valve to assist...

Not certain if the head is available for this, maybe the drayton head is the same.

You will need to drain the heating system or bung the cold feed and open vent to change the entire valve.

Thanks for replying.

So do you think the mid-way valve is definitely at fault then? How much would I be looking at to get a plumber in (South Cheshire area), as I don't think I'd be comfortable draining the system myself?

Sounds from your description that the valve body is stuck mid position.

gas4you said:

Sounds from your description that the valve body is stuck mid position.

Click to expand...

Is it possible to manually move it until I get it fixed properly??

And back to my last question, how much should I expect to pay to get it fixed (or should I try to fix it myself)??

you cant tell from that pic if the head is removeable type or not.

id bet it isnt.

there isnt much on these to go wrong, why dont you turn off the power and strip it down? if its jammed id wager the spindle will need oiling up.

Sorry if I sound like a dunce

Is that the circular metal thing in the centre? I did try taking it apart but didn't look closely at that bit. Does it just pop apart?

EDIT...There's a little spnning cog at the back of it, which has grease on it. Is that what we're talking about it. Do I just spray some WD40 (or similar) directly onto it, or do I need to open the metal casing somehow?

no ignore the motor that you have removed.

the spindle is at the end of the arm that the little cog moves. if it all moves freely then its not a mechanical problem and you need to think about the electrical side of things.

okay, well it was reasonably loose I think, but I've oiled it up a bit, and then put it back together. when i switched it back I pulled the black lever on the side up, and it sounded like some water got release or redirected somewhere.

I think the CH and HW are now working independently, although I can't tell yet if the thermostat is operating properly. I'll keep an eye on it over the next day or two and see if it's back to normal or not.

I'll post an update, but thanks for your help in the meantime.

gas4u and nickso.

thanks for your help, my CH appears to be working again now after I followed your instructions. you probably saved me a fortune! cheers