AUTO AIR VENT

sparky1508 · 28 Oct 2011

Hi everyone,
I have been doing some work on a friends central heating system(open vented with condensing boiler). They told me they had a leak in the airing cupboard and upon inspection i realised it was the auto air vent so bought a new one. Now, here is my problem! correct me if i am wrong but shouldn't the auto air vent be at the highest point in the heating system as air is lighter than water so therefore venting air out of the system.Well i have now realised that they have a 7 foot tall towel radiator in the master bathroom and the AAV is only 3 foot of the airing cupboard floor but not near the wall so can't raise it straight up as it will not be secured to anything. So finally here's my question..... is it within regs to lengthen the pipe and put roughly two 45 degree bends in it so i can clip it to a wall to take it higher than the towel radiator.
Any advice would be greatly appreciated.

bobthebender · 28 Oct 2011

correct me if i am wrong but shouldn't the auto air vent be at the highest point in the heating system [/quote said:
Not necessarily so.. but what you say will be ok to do.

sparky1508 · 28 Oct 2011

So could it be just a faulty AAV and if I just replace it where it is would it be ok. It is quite an old one from the look of it so probably is knackered.

Tibbot · 28 Oct 2011

OP- You've got it wrong. The AAV will be venting a specific high point, the towel rail is vented through it's bleed nipple, the system is vented through the vent pipe to the F&E tank.

plumberdan · 28 Oct 2011

Might be venting the coil on cylinder! Just replace where it is!

sparky1508 · 28 Oct 2011

Thankyou for the reply, i think i know what is going on now as its got 22mm coming out of the cylinder then a 90 going up and a 90 across then there is the AAV and then down 90 again to the pump. So its venting the high point of that bit of the system?????????? If so then i should just be able to change it for a new AAV and all is good. Hope that is correct as it will save me a bit of work!!!!!

sparky1508 · 28 Oct 2011

plumberdan said:
Might be venting the coil on cylinder! Just replace where it is!

Think you are spot on as it is on that bit of the system.
Thankyou so much, it all makes sense now.

bengasman · 29 Oct 2011

Faulty aav plus open vent steamer. You can bet your bottom dollar that the boiler was not installed to spec, but a cheapo cowboy job.
You are likely to find:
gaspipe undersized
system not flushed
controls not compliant and/or wired up poorly
bench mark not filled out, which makes the boiler At Risk.
I would recommend you tell your friend to get a pro in to sort it out, as you are bound to be blamed for everything else that will go wrong, including the damage caused by leaks.

sparky1508 · 29 Oct 2011

It is a Grant 90-140 multipass oil boiler, not sure if it is all up to spec as i'm only working on radiators and bits of pipework but will have a chat with them and make them aware of the things they should be concerned about. Thanks for your advice.

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AUTO AIR VENT

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