How to replace mid position actuator?

[j1mm1nycr1cket]

Hello,
My mid position actuator bgmvsp-23 is stuck somewhere between CH and HW as the rads heat up a little when only the HW side is on.
It seems to me that the actuator can be removed WITHOUT doing any plumbing - is that right? It looks like the actuator mechanically turns a valve so presumably I can pull it away from the 3 port valve without fear of any water escaping? It seems to be sort of clipped on with a couple of catches, do I release those and carefully pull it off? (After isolating the power of course).
I followed the advice on this forum and have ordered a replacement Drayton MA1 but need some tips on how to swap them over.
As the valve is stuck between two positions, do I need to move it back to one position before putting the new actuator on and how do I know which way to move it?

Thanks very much in advance

 

[seco services]

It seems to me that the actuator can be removed WITHOUT doing any plumbing - is that right?

Yes look on the oppersite site of the W M H indicator and their is a black button push it in and lift the actuator off.

It looks like the actuator mechanically turns a valve so presumably I can pull it away from the 3 port valve without fear of any water escaping?

Yes no water will escape.

It seems to be sort of clipped on with a couple of catches, do I release those and carefully pull it off? (After isolating the power of course).

As above but don't need elecy off just to remove actuator.

As the valve is stuck between two positions, do I need to move it back to one position before putting the new actuator on and how do I know which way to move it?

Before going down the actuator route i'd remove actuator and see if the spindle on the valve moves freely.
If so then it maybe the port is just full of crud not allowing the port to fully close or the paddle in the valve is faulty.

More a valve fault than the actuator.

 

[j1mm1nycr1cket]

Ace. Thanks for the reply.

...it maybe the port is just full of crud not allowing the port to fully close

It could well be full of crud as the water in the system looks pretty grubby, judging by the colour of the bled water from the rads
If the port is crudded up, is it possible/easy to clear it..?

If it does turn out to be the actuator, what position should I turn the spindle to before fitting the new actuator? I don't know how to figure out which position relates to W, M or H..?

Thanks a lot

 

[seco services]

If the port is crudded up, is it possible/easy to clear it..?

Depending on the condition of the system water you can run a chemical cleaner through it.
Check the condition of the f/e tank (small one) in loft for sludge etc in the bottom.
As for cleaning the port of hard crud the valve can be removed and the ports cleaned and paddle inspected.

If it does turn out to be the actuator, what position should I turn the spindle to before fitting the new actuator?

Don't matter the spindle only turns a slight distance place the actuator on the spindle and you can turn the actuator slightly till it slides fully down into position it'll line itself up.

But very much doubt the actuator
Go through the programmer settings and watch the W M H indicator move to each position.
You can actually do this with the actuator off the valve.

I don't know how to figure out which position relates to W, M or H..?

W - is hot water calling only.
M - is hot water/heating both calling.
H - is heating calling only.