What's this? Air vent valve?

[Robin66]

Hi. I'm having some issues with air in my system and I believe this should be an air release valve but I'm not sure how to operate it. It doesn't seem to push down or twist. Can anyone confirm what this is? I've attached 2 pics. This hot water tank is on the first floor, the boiler is beneath it on the ground floor, so this is a relatively high point in the system.

Many thanks in advance, Robin

 

[Mottie]

I've got two of those at the highest point of my system - next to the boiler in the loft. One on the flow and one on the return. I thought they were just bleed points for when you fill the system. They just unscrew with finger pressure. Mind you, they've only just been fitted when the system was updated so not had time to seize up yet. Get a pair of pliers on them.

 

[Robin66]

Ok will do. I didn't want to force twist it with pliers only to find it was "push to vent".

Thanks a lot.

 

[ianmcd]

They are manual air vents, you open till water comes out then close as all the air has been removed

 

[FiremanT]

Best to try when the system is cold.