Under Floor Heating - one of the valves sticking?

[AlunRoss]

Hi - I'm not sure what these things in the picture are called, but water flows to each room when the "float" moves down, but one is stuck.

Last year a heating engineer came and unstuck the valve by tapping on it with his screwdriver head.

I've tried that, but no luck - three of the floats move down but one doesn't. I've tried screwing them to different heights, but no effect.

He said that they can easily be replaced - but I have no idea how - or even what they are called.

Any help or suggestions would be gratefully received.

 

[Timmy D]

They’re flow meters and do not regulate the flow through the zone, only measure it.

2 potentials here. If it is indeed stuck, once the system has been balanced, it really serves no purpose. So ignore it.

If it’s not moving because it’s working and is showing no flow through the zone, this lack of flow needs to be resolved.

Each FM is paired with an actuator (typically directly below/above it on the other section of manifold).

Feel the flow/return pipe for this particular zone (so below the FM and below the corresponding actuator head).
Is it hot?
If yes, it’s getting flow, so the actuator is working and the FM is jammed and I’d ignore it.
If no, then the actuator is broken or the pin is jammed closed.
When the stat connected to this zone calls for heat, does the actuator head respond (blue indicator rises) the same as the others?
If yes, then it’s the pin.
If no, then you need a new head and there is still the possibility of a stuck pin.

Then remove the head, check the pin underneath for movement. Can you press it down and does it pop back up when released?
If yes, pin working ok.
If no, it’s stuck. Try and free it up pulling pulling it up with pliers. Once up, push/pull the pin up and down to free it up.
It should now start to work normally (can seize over summer due to no use).
If it still gets stuck, need a new valve body.

 

[AlunRoss]

They’re flow meters and do not regulate the flow through the zone, only measure it.

2 potentials here. If it is indeed stuck, once the system has been balanced, it really serves no purpose. So ignore it.

If it’s not moving because it’s working and is showing no flow through the zone, this lack of flow needs to be resolved.

Each FM is paired with an actuator (typically directly below/above it on the other section of manifold).

Feel the flow/return pipe for this particular zone (so below the FM and below the corresponding actuator head).
Is it hot?
If yes, it’s getting flow, so the actuator is working and the FM is jammed and I’d ignore it.
If no, then the actuator is broken or the pin is jammed closed.
When the stat connected to this zone calls for heat, does the actuator head respond (blue indicator rises) the same as the others?
If yes, then it’s the pin.
If no, then you need a new head and there is still the possibility of a stuck pin.

Then remove the head, check the pin underneath for movement. Can you press it down and does it pop back up when released?
If yes, pin working ok.
If no, it’s stuck. Try and free it up pulling pulling it up with pliers. Once up, push/pull the pin up and down to free it up.
It should now start to work normally (can seize over summer due to no use).
If it still gets stuck, need a new valve body.

Thanks for the prompt and detailed response.

From your description I'm pretty sure the pin is stuck, but I'm not sure how to remove the head.

In the picture below I've lifted the red collar to reveal a nut - should I unscrew this nut to get access to the pin (it seems quite tightly screwed ...)

 

[Ben-gee]

No.
The red nut is on the flow meter, leave this alone.
The pin you are interested in is on the corresponding valve below the actuator head, on the other rail of the manifold - directly below the dodgy flow meter.

 

[AlunRoss]

Hopefully, last question.

Here's a picture of the whole thing - so I unscrew the (white) actuator head to gain access to the pin?

 

[Timmy D]

Hopefully, last question.

Here's a picture of the whole thing - so I unscrew the (white) actuator head to gain access to the pin?

Yes, either unscrew or push a little button to pop the head off, underneath will be a pin.

I changed my valves the other day due to sticking/leaking.

Here’s a couple of pics to help.

 

[AlunRoss]

Excellent! Thanks very much for your help - it's much appreciated.