Vokera Excell 80SP - Auto Air Vent Failure

[Antony2008]

Last night my faithful ? ? old boiler stopped delivering dhw. On first inspection there was very low pressure and a wet cellar head floor. I recharged the boiler to 1bar and traced the leak to the auto air vent, which was dribbling out from the aperture in the small black cap (water still flows regardless of it's tightness).
A couple of hours before I found the problem, as the ch turned on I heard the upstairs radiator gurgling as if there were air inside (which is possible as I part emptied the system a couple of weeks ago when re-fitting a towel rad').

A couple of points:

What causes water to flow out of the auto air vent?

Is the auto air vent servicable or do I just need to replace the auto air vent?

Once fitted/serviced, should the auto air vent's small black cap be finger tight?, tightened then backed off ¼ turn? ??

Are there any other measures that I need to take, such as check out another component that may have caused the problem, or any preventative maintainance that needs to be done.


I'd appreciate anyone's input; many thanks in advance.

Antony

 

[Agile]

The cap should be gently tightened until you JUST start to feel more resistance. That will let air out but restrict the flow of water a little bit if it starts leaking.

They are better replaced.

They can sometimes be cleaned, boiling in citric acid is good.

Its not a very common problem on your model.

Tony

 

[superdupergasman]

You are just aswell to replace the AAV as its only 7 or 8 quid for a new one, just unscrews out the pump housing.

Srew new one in with a little PTFE tape and jobs a goon un'

I would diagree with tony and say leave the cap open a 1/4 turn as this allows the thing to do its job, getting rid of air out of pump if it gathers.

 

[Agile]

Yes, I worded that badly but I knew what I meant!

I have edited it so that others will know as well.

Tony

 

[Antony2008]

Thanks for your sound advice agile & superdupergasman. I sourced the AAV from the internet (£8.46 inc vat/postage, tho' took 2 days to arrive).
A couple of wraps of PTFE and we're now able to shower at home !

Thanks again.

Antony