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Almost every Grant I attend has a leaking AAV, this one is on a Firebird. Changing them doesn't fix it, what do you do?

ImageUploadedByTapatalk1377677917.496321.jpg
 
If its a sealed system Usually to do with expansion vessel
Needs re charging or undersized
 
Normally mucky system. Recommend system is flushed.

If you disassemble Aav once removed normally find that muck trapped between top of float and lid of chamber or guide for float is mucky, thus when air has left system Aav isn't reseating properly. Think most Aav are tested to. 10 bar so prv should kick in before it fails?
 
Funnily enough, i posted the op while at work, the very next job was one of those 'services' where actually its a leak, kitchen roll soaking in base of boiler cab -

Custard: "can you fix while servicing?" -
Me: "No, lets fix the leak then see if there is time to service it..."
which there wasnt so they'll have to pay the call out.

Grant, another AAV - immediately after posting the above, how timely! Fortunately a gravity on a bungalow with idyllic loft access etc.
 
Heat seems to ruin them & cause them to leak.
If they are on a colder part of system they tend to last & last.
Sadly can't do much when they are screwed straight into top of boilers, - unless somebody knows of better types.
 
Vent air from system and then screw black plastic cap in. It wont leak then
 
Fit Spirotops the water level is well below the valve so tends not to suffer so much with dirty systems.
 
I agree, I try to leave them open when commissioning, then after I'm happy there's no air, I tend to shut them.

And being directly above the main heat exchanger can't help on the grants.

You can get better quality aavs, like the solar ones. Never really worth it though as things like this gives us work ;)
 
I always have a load of AAVs in the van and if I come across one on a service that looks dodgy I replace it as part of the service.
 
Used to use Winns AAVs, built like battleships and lasted for millennia! Cost a packet tho'! Now use Spirotop and have virtually no problems. (touch wood!)
 
I've seen recently that new Grant boilers now don't have AAV's! they have brass air "pips" like on radiators.
What I was wondering is; would it be worth keeping a few in my van so I can fit these instead of changing the AAV's for another one that is just going to leak again??
 
i remember seeing the mr combi dvd whilst in collage, and remember him pointing out buggerd auto vents and always blaming it on undersized expansion vessels (or obviously undercharged ones) , his advice was to isolate. completly drain the boiler, leave the drain off open then fill the boiler so that clean water would flow thru it and out the drainoff to flush it. then pour a jar of x200 inside it and recharge or fit a bigger expansion vessel , before fitting a new aav!!!
 
I've seen recently that new Grant boilers now don't have AAV's! they have brass air "pips" like on radiators.
What I was wondering is; would it be worth keeping a few in my van so I can fit these instead of changing the AAV's for another one that is just going to leak again??
The new grant combi has 2 aavs and the ordinary boiler has a radiator type manual one on the return.
 
I put this to Honeywell when on course and they said "AAV's are solely made to help with filling the system" they are not designed for being left open.
 
don't shoot the messenger!! but seriously the boiler cover cant be taken off by non GSR engineers but should not be left open, Honeywell say leave shut and MI say leave open, how conflicting!!
 
don't shoot the messenger!! but seriously the boiler cover cant be taken off by non GSR engineers but should not be left open, Honeywell say leave shut and MI say leave open, how conflicting!!

I cap prv with a 1/2 nut and close all Aav just to be safe ;)
 
do you mean something else? if you cap the "pressure relief valve" the system will not relieve pressure when there is a problem and potentially explode, so hopefully you don't "cap the PRV"
 
do you mean something else? if you cap the "pressure relief valve" the system will not relieve pressure when there is a problem and potentially explode, so hopefully you don't "cap the PRV"
Corse he's joking :)
 
Are you joking? I went to a leaking PRV today and capped it :S shouldn't I of done that?
 
Only use AAV's for filling up and then close them. No reason to for air one up and running.
 
I always have thought same.
AAVs are unnecessary & cause a lot of leaks, damage & call outs.
Stuck straight into hottest parts of boilers or pipework just guarantees they leak.
Manual vents are fine for a heating engineer, as he or she will know what needs bled when systems are fillled.
AAVs also cause air ingress if fitted on suction side of pipework.
 
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It was a wind up Kimbo lol.
I think Grant have finally had a good idea of ditching them on some boilers.
 
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