Possibly faulty mid position valve - have I done a temp fix?

[mjb1975]

Hi all

First post - and very new to reading up on CH systems/problems!

About a month ago, I noticed that my boiler wasn't burning (although the pilot was on) when I put the hot water/heating on. It's a Glow-worm back boiler, installed behind a gas fire. After reading the manual, I checked the boiler and noticed that the main switch (with off, pilot/ignite, and burn) had moved somehow back to pilot/ignite. Once I moved it round to burn, everything seemed to go back to normal.

A week or so ago though, I noticed the boiler wasn't burning again, with the controls on. This time, the switch was on the burn setting so nothing I could do there. I even tried turning it off and then re-igniting. Still no burn.

I then read up on a few things here and shifted my focus to the pump (a Grundfos model) by my hot water tank upstairs. I unscrewed the big screw on the front and tried turning the spindle inside - all seemed ok. Did it all back up and nothing had changed.

I then turned to the mid-position valve (ACL Lifestyle model) and noticed that the indicator on the side was seemingly stuck on 'W'. It did allow movement towards the middle but it bounced right back to 'W'. We do have hot water so that makes sense but the radiators are always cold. The boiler burns if we need hot water but not with just the heating on (and the indicator stays on 'W').

I tried taking the front case of the valve off and checking the motor. The spindle turns ok although I wasn't sure if it was as easy as it should be. I sprayed a little WD40 on it and put it all back together again. No real difference.

However, I also pressed the larger black lever on the top of the valve. This seemed to click into a fixed position (down) and then the indicator on the side moved to 'M' (again, quite fixed in position. It moves slightly towards 'H' but bounces back to 'M' and doesn't move towards 'W' at all).

The main result here is that both the hot water and the radiators work normally now - both on at the same time. However, I'm not sure I've done anything permanent and may have just 'bodged' a fix. What does the bigger lever on the valve do? Just need a bit of advice before calling my boiler guy out (for possibly no reason but I would like him to check the system over).

Any input would be much appreciated.

 

[seco services]

sounds like the motor has failed in the valve actuator.

the lever on the end thats on a spring can be moved into the m position and will give heating/hw when hw called for.

the lever is a means of putting the valve in mid position when filling the system or draining the system.

 

[buck51]

Do you have a room stat??? IS it turned down??? I only ask as you have not mentiond it
A few people seam to be having problems with this type/ make of valve my self included //www.diynot.com/forums/viewtopic.php?t=169872
try this link but it would appear we had the opposite problem

 

[mjb1975]

Thanks for the quick replies.

I do have a room stat and I've tried turning it right up and down but no real change. It does make a quiet click at about 18 degrees - I assume the temp it's sensing and thus trying to turn on/off as required but the boiler doesn't burn.

I did have the motor pictured out and the little spindle on the rear of it (the opposite side from that shown above) does move round, and you can hear the whirring as you do that, so I assume it's ok, but I have no frame of reference.

However, I'm slightly more concerned about the larger black switch on the valve box now. It's pressed right in and won't now budge. The smaller indicator lever on the side is on the 'M' position and doesn't move regardless of whether I have the HW on the control panel (by the stat) or just heating, or both.

Just not sure if the switch is meant to be in the down position (I assume not) and whether I should do something about it in the short term. I don't think I have the knowledge to change the valve completely (I think/assume it's the older type which needs complete change) but would attempt to replace the motor.

I have a feeling it's the mechanism behind the motor though - that seems to be what the larger switch connects to. I've tried Googling for further information but am a bit stuck now.

 

[seco services]

push the lever on the end in and push it over then pull it out it will free itself from the clip.

you say the motor was whirring round.
is that by you turning it or by the live to the motor powering it ?

 

[mjb1975]

Righty - I've flicked the big switch back and I seem to be back to square one (which isn't necessarily a bad thing) - that is, the stat is ok (22 degress or something) and with the heating and the hot water on, the vale is pointing to 'W'.

The radiators are cold. When nothing is on, I put the heating on and the boiler doesn't burn. When nothing is on and I put the hot water on, the boiler burns.

Am I on the right lines focusing on the valve? I was gonna pick up a motor and see if replacing that makes any difference. Worth it for £12-15 compared with a call out charge and repairs from a pro.

With regards to the motor, yes, it turns/whirred using my fingers (the leccy was switched off before I took it apart, I assume correctly?).

Any other advice guys - it's much appreciated!

 

[seco services]

with the heating and the hot water on, the vale is pointing to 'W'.

if both heating & hw are calling for heat it should be in the M position.

The radiators are cold. When nothing is on, I put the heating on and the boiler doesn't burn. When nothing is on and I put the hot water on, the boiler burns.

heating on its own. the valve is not being moved across to the H position.

 

[mjb1975]

Cool (like it is in my house ).

Does that make it most likely to be the motor then? Must admit, using the manual switch on the top, it does seem to move quite freely between the different positions so assume the mechanical part of it is ok...

 

[seco services]

either the motor has failed or your stat is not sending a live to the valve.

to check this with a multi meter turn heating on, wall stat up and then check for live at the white wire to the valve.
if thats live the motor has failed if it dead then then problem is further back.
9/10 times it'll be the motor.

 

[mjb1975]

Hi all

Been a while since I did anything on this but problem continues. Since my last post, I've replaced the motor in the valve with a new one but I don't think anything has changed. The 'H, M, W' indicator needle still doesn't move to 'H' when I put just the heating on although, perhaps strangely, if it's already in the M position, I can push the manual lever over a small amount and the motor then seems to kick in and move it all the rest of the way to H.

If I have just the CH on, it seems to lock in the 'W' position - the manual lever then doesn't move at all.

Maybe I didn't fit the motor right? I wasn't 100% on where the manual lever is meant to be when fitting the new motor. The motor packaging said move it over 'to the left', fit the motor, then check for manual movement by moving it over to the right and releasing. That's what I've done but something's still not right.

Any ideas? Have a feeling it's now in the new valve territory - in which case I'll get my plumber out...

Untitled

• mjb1975
• 14 Apr 2009
• 1

 

[seco services]

so long now i can't remember.
have you remove the complete head and tried it in heating etc ?

 

[Ryanmac]

The large black lever moves the moter to manual/auto. Putting it into manual will give you both heating & hot water at the same time. Not very efficient. It shounds like the motor has stiffened up (i've changed a few of these recently due to the same problem) I would change the valve, job sorted. Check the colour or the water and inside the valve itself when removed. (If it's jet black the chances are you will need to flush the system out as this is what will have more than likely caused the problem. If it is dirty water and you don't flush then you pay for another valve that will knacker up again in no time at all.)

Ryan

 

[mjb1975]

Hmm, was wondering about sludge (although didn't think that would affect the valve working correctly or not). When I used the bleed valves on a couple of radiators (to check for air) I did notice the water was quite dark, even black, quite briefly before running clear-ish.

Might be some sludge but I'm not sure that would be a cause. Certainly a good idea to flush out if I do get the valve changed.

Changing the whole valve would be a job for the pros for me. I won't do that myself.

Will try taking the motor/switch apart, use some WD and see if anything changes.

 

[seco services]

is that your pic or is the valve upside down ?

 

[mjb1975]

Sorry - that's my pic. If you turn that pic 90 degrees clockwise, it'll be like it is in reality. The narrow pointy part of the motor is pointing up.