dodgy actuator? Tower mp3-22c

[papadelta]

Hi, wondered if anyone could help with Tower mp3-22c problem. For the past 3 days, in the morning, when both hw and htg come on, the actuator moves into position, but then gets caught in a continuous cycle where it slips back a little and then re-engages and returns to where it was. The problem only seems to occur when hw is on (htg alone is fine).
We've mainly noticed this in the morning, even though in the evening we have hw and htg on simultaneously.

I believe the actuator was replaced 1 yr ago.

Any help much appreciated.

 

[Agile]

it sounds as if it may have a slipping cog!

Tony

 

[Slugbabydotcom]

It seems as though the head may have been replaced last time when the valve was stiff to turn and the complete valve should have been renewed.

If the valve is stiff then that means the actuator head has more work to do and will wear quicker

 

[papadelta]

Thanks for the responses guys - I've just been having a good look at it again - the actuator/cog/ratchet look as though they're working fine - no slippage. The problem is with the mid-position - it can get to it's end points OK. It seems that there's some kind of feedback to the controller which is misreading somehow.

Shining a torch inside the actuator, I can see two strips of metal - I'm guessing the position of the actuator against these feeds back to indicate the valve position. Not sure if these strips can somehow warp over time and cause it to continuously cycle around the mid point?