One radiator always needs bleeding

[Tezbedz]

We have one radiator, downstairs in the hall which always needs bleeding. I fitted a new drain valve to it a few months ago.

Would there be a fault with it? There is nothing leaking out, I have laid paper towel on floor along length of radiator and no evidence of leak.

Does this mean it is sucking air in?

Valves were wrapped with PTFE before fitting. How can I remedy this?

Thanks for your help

 

[petertheplumber12]

It is because the air is not being vented out of the system properly.

 

[Tezbedz]

Thanks and will that only affect one radiator?

The end of the vent pipe into the tank in the airing cupboard is underwater and occasionly I have heard it gurgling.

 

[petertheplumber12]

The pipe that vents air into F&E tank is teed off the 22mm flow pipe from boiler. The ideal situation is that the vent pipe tee's off by going vertically straight up from tee, and the pipe to pump then goes horizontally to pump, the cold feed can be teed into the vent or be teed into the flow pipe within 150mm of the vent pipe. Then most of the air produced by the boiler heating the water will be vented out before it goes into the system.
The air always goes to the radiator that is first to get hot or nearest the pump in the plumbing, to prove it's air vent let the rad fill up with air then the air will go to next rad in the circuit.javascript:emoticon('')

 

[45yearsagasman]

Is it air or hydrogen I ask myself?

 

[Nige F]

I`ve lit a virtual match and it`s hydrogen