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

[mjb1975]

Hi all

Still ongoing (but the weather means it's not a high priority!).

On Saturday, I decided to take the motor off the valve again (I'd fitted a new one) and have a play about with the manual lever - wasn't sure where to place it before fitting motor, etc. When I did that, I just left it as I assume nothing had changed.

However, when I put the heating on, the boiler came on! It hadn't been doing that. The valve was pointing to the right 'H' setting. I asked my girlfriend to use the programmer while I watched the valve. She put the HW on (as well as leaving the CH on) and, yes, the valve moved to the mid-position. I asked her to turn the CH off and, again, it moved to the correct HW-only positon.

I thought, great, it looks ok now. However, on Sunday, I was back to square one - the HW was fine but the valve wasn't moving when I put the CH on.

Given that it seemingly works but then doesn't, is there anything else it's pointing towards now? Clearly, it appears the motor does actually work fine, albeit intermittently.

Wiring? Blockage, etc??

Any help appreciated so I can avoid a professionals charge for something that might be quite straightforward.

 

[seco services]

does it work if you remove the actuator and operate it ?

 

[mjb1975]

If you mean the CH/HW functions work if I manually move the lever - yes, they all work fine.

On the basis that the original motor had gone, I've replaced it but no different really. Confused me that it worked normally (briefly!) on Saturday though!

 

[seco services]

no remove the actuator seperate it from the brass valve and try ch/hw

 

[mjb1975]

Ah, right. So I'd turn the leccy back on without the motor attached and then put the CH/HW on and move the manual lever to the appropriate positions?

If so, I can try that tonight.

 

[seco services]

no leave the lever just seperate the whole of the plastic actuator from the brass valve. and try ch/hw from your programmer and see where the pointer moves to.
sounds like the brass valve is faulty and holding it from moving fully.

theres a black button on the back of the actuator that will seperate the two parts.

 

[mjb1975]

Ok. I was operating on the basis that my valve was one of those older ones where the white box part doesn't detach from the valve but I'll check for a black button tonight.

 

[mjb1975]

Well, deffo no black button on the back of the actuator. There is a label that says 'warranty expires 12/99' so that might give an indication of age!!

This is what it looks like with the motor off - not sure what to do next though.

Untitled

• mjb1975
• 20 Apr 2009
• 1

 

[seco services]

if you push the black lever over to manual it takes the valve to M mid position.
then if you hold lever in manual then push the metal cog section it will go over further to H position.
you will feel it go fully over cause it will activate the microswitchs.
check if its free and moves all the way.

 

[mjb1975]

Yep, all checked out. The lever moves to the middle fine and then the cog bit moves the rest of way with some light finger pressure. Can hear the microswitches click on/off too. All looks good there.

 

[seco services]

that proves the paddle in the brass valve is free etc
do it a few times to make sure then refit motor and try

 

[mjb1975]

Ok, cool. Wiggled back and forth quite a number of times and then locked it in manual/mid and refitted motor.

Put CH - nothing. Boiler lights when I put HW on though (as before). Valve not moved and, in fact, manual lever very tight (expected maybe if the HW is on?). When I put both on, it doesn't move. When I put just the CH on, it doesn't move.

However, if I turn everything off, I can manually move the lever to the mid position (with some resistance and I can hear the motor whirring (under my pressure though)). It then moves to the CH position under it's own power and, naturally, when I put the CH at the programmer, the boiler fires normally.

I then tried putting both on and, yes, the valve moves back to mid. I then turned the CH off (so HW only on) and it moved down to the HW position. But it doesn't move back the other way if I put the CH back on or just the CH.

It's as if it gets stuck in HW position or something.

 

[seco services]

don't fit motor with lever in locked position. thats to far over.
take lever out of locked position and let it fall to its relaxed position fit motor.

 

[mjb1975]

Ok - done. Took motor off, unlocked lever, jiggled back/forth for good measure and then let it sit in the HW postion. Refitted motor and turned CH on.

Nothing from the boiler and the valve doesn't move. Lever stuck pretty firm.

(thanks for all your help on this!).

 

[Z4Roadsterman]

Just found your post while looking around - I have exactly the same problem. Looking at the motor control components in the valve it looks like one of the resistors has con open circuit. You photo shows tha same discolouration to the same resistor.

Did you fix it or change the whole valve?