Understand Air Admittance Valves - can anyone help please

foreversummer

Hi

I had a problem with a sewage smell in my loft. On inspection by my plumber he noticed that the air admittance valve had fallen off leaving the pipe open. He said it had not been put on right and therefore he glued it on.

I am however confused because he said that ideally the stack should be vented up through the roof.

I have two soil stacks in my house, one is out through the roof but the other ends in the loft with the now refitted aav. He mentioned something about venting the stack with the aav to the other stack. But I got lost there. Maybe I misunderstood what he meant.

Can anyone who has five minutes explain what my options are. Is it safe to leave it as it is?

Foreversummer

ValHaller

For the stack with the AAV, it would be perfectly acceptable to vent to air - but not in the loft, hence the AAV to keep smells in and admit air if required. He is saying that if you connect this stack to the other stack which is already vented to air, you will have done everything required with this stack.

cyclonebri1

I think the previous post is wrong.

The whole point of an air admittance valve is that it simply does not emit, it admits.

So, it can be sited in the loft, it can even be sited in a bedroom or bathroom. And thats the whole point, they are used when the pipe cannot be vented to atmosphere. They don't stink as they only allow air in after the crap is flushed, (for the grounded voyeurs), ;)

muckybutt

As stated above AAV's are designed to only take air into the system, the diaphragm in the unit should not allow any air the other way so you should not smell anything, if you are getting smells with the AAV on then I would say the diaphragm has failed.

As for putting it through the roof - sounds like that's a ploy for some more work and a bit more cash !

plumb1_2

I have seen the seals on AAV valves twist and not seal, sometimes due to the pipe being dry. And also seen them come off when there has been back pressure in the vent.

I would always try to open vent a stack, and since there is one to join to in the loft, personally i would do it. £150- £200

ValHaller

cyclonebri1 wrote: »

I think the previous post is wrong.

The whole point of an air admittance valve is that it simply does not emit, it admits.

So, it can be sited in the loft, it can even be sited in a bedroom or bathroom. And thats the whole point, they are used when the pipe cannot be vented to atmosphere. They don't stink as they only allow air in after the crap is flushed, (for the grounded voyeurs), ;)

I challenge you to find anything wrong with the previous post which is:

ValHaller wrote: »

For the stack with the AAV, it would be perfectly acceptable to vent to air - but not in the loft, hence the AAV to keep smells in and admit air if required. He is saying that if you connect this stack to the other stack which is already vented to air, you will have done everything required with this stack.

cyclonebri1

ValHaller wrote: »

I challenge you to find anything wrong with the previous post which is:

Ok,:p the previous previous post, just trying to clarify for the OP not you, + Id actually missed the bit where the OP stated to "other" pipe went through the roof, I took venting to air to be the air in the loft, my shortsightedness, not lack of understanding:D

But I have checked the spelling and grammar of your post as protection against the might of the S&G Police if I said there was nothing wrong with it. ;)

Ianwzzz

Aav's are supposed to be fitted internally and should not be fitted outside as they can freeze shut.

southcoastrgi

Ianwzzz wrote: »

Aav's are supposed to be fitted internally and should not be fitted outside as they can freeze shut.

are you still asleep ?

it is internal it's inside the roof

some can be fitted externally using the polystrene (spelling & can't be ar*ed to look it up) cap that it comes in, although tbh I can't see the point of fitting one externally

foreversummer

Thanks guys for your replies. I think I understand the issue know. The thing looks to be working properly now and the other stack is vented through the roof no too far away, so I think it would be possible to vent it to that pipe if I feel the need.

Many thanks.

Foreversummer