Glo Worm Swift Flow 75 leaky auto air vent - again

3 May 2007
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United Kingdom
We have the above boiler which was working ok until Xmas last year, when we had to replace the automatic air vent which was crusty and leaking.
The new one started leaking again, :mad: the little plastic cap is looking worn out. It hasn't been touched since the air vent was replaced. The old vent had a brass cap I'm sure.
When we ordered the new one it was 29th December and had to pay a premium (£25) for postage to guarantee delivery. And it's a BH again!
Will we be able to get just a cap, or will we have to get a whole replacement air vent?
What could have caused it to go so quickly?
OH has drained down the system so we are back to boiling kettles and saucepans for washing. :cry:
We bought the valve from keeptheheaton
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rob884 said:
Just twist it so it closes.

Not sure I understand, twist what? The (soft) plastic cap has no thread on it and has sort of splayed at the bottom (It's like the valve cap on a tyre).
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Try firmly 'tapping' it with a wrench to see if it has just got stuck. Could be your ch system water is so dirty that it is fouling the auto air vent :?:
Sorry, but OH is adamant that it is the fact that it is because the plastic cap has come away and won't screw back on that is why the vent is leaking water.
I don't know any different.
Is this why it's leaking or is it because the whole vent isn't screwed home tightly enough.
What is the cap for? It has a little 'air hole' in it (I think)
Is it just a dust cap or something.
OH is a bit peed off that I'm posting as he thinks he knows best.
He was a plumber in another life - about 18 years ago.
I just want hot water again.
I know he's going to get another complete air vent, but to me it seems a waste of time if he hasn't got to! Men!!! (Sorry guys)
I don't want to intefere (I'm a woman for God's sake;))
If it was something I could attempt myself I would, but will not get involved with water - electric I'm fine with.
the cap has nothing to do with it. its there to shut the vent off for whatever reason.

the reason its leaking is because the rubber o-ring inside the vent has been damaged gas4you said its probably dirt or something else in the water eating away at the rubber seal.

get a new AAV fitted and then investigate to see if your system water is manky or if there are other issues to deal with or you will probably keep going through AAV's.
Thank you.
So presumably, the o ring is part and parcel of the unit and cannot be replaced?
So it will be a new unit then.
Thanks again for your advice. :)
moiraf100 said:
Thank you.
So presumably, the o ring is part and parcel of the unit and cannot be replaced?
So it will be a new unit then.
Thanks again for your advice. :)

depends on the AAV in question but in general its a sealed unit so yes its a new one you need.
just screw the cap down, if you have lost the cap take one off a car tyre and put that on and tighten it down
When you get the new one, and the boiler is vented, screw the cap down. Very occasionally, let the OH open it and then close it again if he feels the need to mess.
I see lots of these when servicing oil boilers and for some reason, particularly on combis, they calcify through persistent weeeping and then leak. I leave them shut after service and never get a call back. I can vent at the next service.
+1 once the boiler is filled I close the AAV doesnt matter the make they all leak

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