Flamco Flexvent

[brighton68]

Why do I have a Flamco Flexvent in place of a bleed valve on one of my radiators?
The radiator in question needs bleeding ie its warm at the bottom and cold at the top, but clearly there is no way to bleed it...

 

[gas4you]

These are usually an automatic air vent. Can you turn th black knob on the top? If not it may have scaled up.

This is probably a radiator that need constant bleeding for some reason.

 

[brighton68]

This one has a screw on metal cap - I guess it might be quite old. Sounds like it should maybe be replaced.
Is it as simple as turning off both valves, unscrewing it and screwing a new one in?

 

[gas4you]

Yes, but if it is a sealed/combi system then you will need to de-pressurise the rad/system first.

Be prepared for some water loss when undoing it.

 

[brighton68]

I think it's a sealed system (there is a red expansion chamber next to the boiler)
I isolated all the other rads in the house except the one with the aav (in a dormer bedroom) ran the system for an hour and the top half still stays cold)
Does this mean the top of the rad is just full of air? - and the aav is jammed.
If the rad is full of air, if I undo the aav after switching off the valves where will water come from?
How do I de-pressurise the rad/system?
Would it be better to get a plumber or heating engineer?

 

[gas4you]

Yes sounds as thought he aav is jammed. You could just try slightly undoing the aav on its thread until you hear some air come out. When water appears do it up again.

Somewhere near the boiler or exp vessel you will have a filling loop, usually a silver flexible pipe with an isolator on either end. Open both of these until the presuure reaches just over 1 Bar, then shut both of them.

 

[brighton68]

I replaced the aav with a new one but this has not resolved the problem of the upper half of the rad remaining cold.
Any suggestions as to what to try next?

 

[brighton68]

Problem solved!

I have now refitted the aav with an elbow so its sits vertically and hey presto, the system operates fine.

I was wrongly advised in the plumbing merchants that "this one just screws straight into the rad"

Thanks for your posts, Dave(gas4you).

 

[gas4you]

Sorry I assumed it was fitted vertically Problem with not seeing the problem on here