Underfloor Heating: one zone not heating

[homeCP62]

hello,

My flat has a combination of underfloor heating (4 zones, 3 thermostats) plus some radiators in some rooms.

Regarding the underfloor heating, one zone heats up fine, 2 other (same large space) heat up slow, and 1 does not heat at all. I identified the pipe on the manifold and it stays cold.

I've been looking on several forums, found that one issue might be the zone actuator with stuck pin.

Problem 1: I do not know how to reset this pin, as none of the advice found seems applicable. The actuator are from Giacomini. I do not seem to be able to remove them easily to access the pin.
Question: where could I find some info on how to check / unstuck the pin on this kind of old actuator ?

Problem 2: what seems to be the flow valves look dirty (see photo)
Question: is my assessment right ?

Many thanks in advance for any info or pointer

Cheers

 

[Madrab]

Is this your property? Obviously, some of the actuators are broken. other may be sticking. The test would be to take them all off and check the pins below are moving a few mm up and down and then check the loops get flow/heat up.

Certainly time to look at the actuators and get them changed I would say.

 

[Agile]

Looks like the heads are held on by the screwed clamps underneath. With two broken and replaced with zip ties.

Jubilee clips would probably be a suitable solution if you needed to remove those.

 

[homeCP62]

Thank you both.

I rent the property so I will need to escalate to the owner.

Re: actuator, I was hoping to be able to unstuck the pin myself for the circuit that remains cold but it looks too risky (and the zip tie does not inspire confidence). 3 out of 4 seem to be working ok so unlikely that the owner would change all of them.

Re: Flow valves: is the color normal? I cannot find similar devices in my research.

One think I forgot to mention: now that heating is on, the pressure drops from 1 bar to 0.2 bar over 2 weeks (bottom right of Global vire picture), putting the boiler at fault. I need to re-inject water in the loop to increase back to 1 bar and reset the boiler.

 

[homeCP62]

Some more info: see attached an infrared picture of one actuator / flow valve working (to the left) and the one not working (to the right).
It looks like the transparent flow valve is blocking the flow (warm water on top, cold water at the bottom).

Is that possible? What would need to be done?
Does anyone know the reference / have some documentation about those transparent pipes ? (which I call flow valve)