Issue with Central Heating Manifold

[kofi2003uk]

Hi everyone,
i had a garae converted and plumber installed 3 additional rads about 6 months ago. the rads in the garage conversion are connected via a manifold.
been working fine until about a week ago. one of the rads doesn't get enough hot water suddenly even though no change has been made on the manifold.

the lock shield and TRV on radiator are all fine.

the problem circuit is marked with green arrow(inlet)-seems the circuit for that radiator isn't opening as much as it used to for some reason. its set for the flow gauge to drop half way down automatically.
however when the heating comes on in the morning, it open a tiny bit. if i turn the the circuit off and on again at the red arrow, then the circuit immediately opens/flow gauge drops to where its supposed to be and rad starts working ok for the day

however the same issue repeats the next morning when the heating comes on and can be fixed the same way explained above.

any ideas on what might be causing this please? picture below

many thanks

 

[oldbutnotdead]

That's a very posh manifold- considering you've got lockshields and TRVs on the radiators I wonder if it isn't a bit overkill and possibly designed for a different purpose.

Its possible there's an air bubble trapped in the internals somewhere - any way of bleeding that bottom manifold? Or the top one for that matter

 

[muggles]

That's a very posh manifold- considering you've got lockshields and TRVs on the radiators I wonder if it isn't a bit overkill and possibly designed for a different purpose.

Its possible there's an air bubble trapped in the internals somewhere - any way of bleeding that bottom manifold? Or the top one for that matter

It's an underfloor heating manifold. You're right that it doesn't really belong on radiators, although if it works then all good. I agree this sounds like an airlock somewhere

 

[oldbutnotdead]

It's an underfloor heating manifold. You're right that it doesn't really belong on radiators, although if it works then all good. I agree this sounds like an airlock somewhere

Wondered about that but i thought UFH setups all used weird tube sizes. And tbh I like gauges and things to look at anyway

 

[kofi2003uk]

thanks Chaps. i will bleed the manifold and see what happens. will update
many thanks and i appreciater your resposnses

 

[kofi2003uk]

update ... well no joy. bleeding did not resolve it. glass gauge still drops only one level and stays there. strange thing is as soon as i turn that circuit off and then immediately on again, gauge drops halfway down as its supposed to and radiator starts working fine.

i hope someone has some idea what is causing this. as mentioned earlier, system has worked perfectly for the past 6-7 months until now.

many thanks