leak from automatic air vent

[Ralp]

Hello, used this site last year and was a great help, hoped someone could help again. I have a sealed heating sytem using a combi boiler. Up in the loft there are a couple of automatic air vents (bottle air eliminators - I have heard them called) fitted to the top of 15mm vertical pipework - I believe they have a float inside to stop water getting out but will let air out. However one has been leaking quite badly - my question is that the cap is loose, should it be? when i tighten it up the leak stops but I think this is also stopping any air getting out?? - Basically can it be remedied or do i need to change the whole vent bottle. Would it be the float sealer that is broken?? - any help much appreciated ........... oh and sorry for length of message

 

[gavinda]

tightening the cap is how some of my colleagues repair it, but this tends to remove the 'auto' part from automatic air vent do the cap up for now and if you can drain the system yourself its not much to replace them. and take advantage of and empty system to reinhibit it too

 

[Ralp]

thanks for such a speedy reply - Yes I have drained system down before - so I should replace the whole bit? - would you mind explaining what the likely cause of this vent leaking is? - cos i will check the other one while i am at it - also when i change it - the cap should remain loose yes?

 

[gavinda]

ive managed once to clean one out but mostly just change the lot for peice of mind. as for wh there could be some muck in the system. seeing as you can drain the system...stick some restorer in for amonth then drain fill and heat it about 5 times and then reinhibit on the last fill

 

[Ralp]

thanks so much for you help

 

[gavinda]

8)