Invensys Actuator TA/M4 seems stuck

[Rincewindwiz]

Hi All
My central heating controls do not work because, I think the actuator does not work
I can manually move the 3 position 'tap' (normally driven by the actuator) to get hot water or central heating but the electronic actuator seems stuck so the thermostat has no effect making controlling the heating impossible!
If I remove the actuator from the valve, I can feel it vibrating ( presumably as the motor turns) but the spindle that engages with the the 3 way valve doesn't move. I cant even move it by hand. Is there a way of freeing up the spindle?
Or any other suggestions as to how I might fix this thing?
Thanks for any (reasonable -) suggestions

 

[Harry Bloomfield]

I cant even move it by hand. Is there a way of freeing up the spindle?

If you are saying the actuator, even when removed from the water valve, is failing to turn, but is just juddering - that suggests the actuator is completely worn out. You need to fit a replacement actuator, because they are not usually repairable. You can buy and replace the motor, but the fact that it is trying to move, juddering - suggests that the motor is OK.

It's also worth checking the actual water valve spindle is free to turn - it should be almost possible to turn it with your bare fingers/ easy with a pair of pliers.

I had lots of problems with my spring return 3-port actuator over the years, the least reliable part of my heating system. Spring return, means that the actuator motor is powered the entire time the heating is in use, and frequently on the move. I have since swapped it for a MOMO type valve and actuator, which has proven to be 100% reliable since I installed it. It seems a much better idea, they power to position, then power off, the motor is not constantly fighting a against the tension of a spring. They sit unpowered, until a change is needed in the valve position.

 

[Rincewindwiz]

It doesn't judder - rather I can feel the vibration of a motor turning; same feeling you get when a pump is running but it has to be in the actuator as the only outside connection are the wires.
But I am surprised that if I grip the spindle with pliers I cant turn it at all.
Trouble is there appears to be no direct replacement for the Invensys TA/M4 actuator

 

[Harry Bloomfield]

Trouble is there appears to be no direct replacement for the Invensys TA/M4 actuator

https://www.wolseley.co.uk/product/drayton-ta-m4-actuator-only-3-position/ £269 = OUCH!

 

[Rincewindwiz]

Indeed but they dont have any - not AFAICS does anyone else
The only one I have found is this comedian https://www.ebay.co.uk/itm/304786667328

 

[Harry Bloomfield]

Indeed but they dont have any - not AFAICS does anyone else
The only one I have found is this comedian https://www.ebay.co.uk/itm/304786667328

Are you able to swap both the water valve, and the actuator, for a completely different 3-port model?

Is it used in a Y-plan, S-plan, T-plan or what?

 

[Rincewindwiz]

Well that is probably the only solution but that would be pushing my limited plumbing skills too far. Im happy to replace stuff but re-engineering is a step too far. Anyway, I will give up and call a plumber and see what they say.

 

[Harry Bloomfield]

Well that is probably the only solution but that would be pushing my limited plumbing skills too far. Im happy to replace stuff but re-engineering is a step too far. Anyway, I will give up and call a plumber and see what they say.

If the water valve is Like a T shape pipe layout, with the spindle poking straight up from the top of the T, then the plumbing might be as simple as drain down, remove the old valve and fit the replacement. Some of the experts on here, should be able to advise on what system type you have, and be able to advise on rewiring to suit the new actuator head.

Post some photos of your pipework, around the valve, cylinder, boiler, time controls and thermostats..