Air admittance valve / soil vent pipe

[joe90]

As long as any smells etc can vent and also no vacuum can be created it will work.

[yebaws]

Will be AAV in the building. But would the setup be building regs (Scotland) compliant?

[PaulJS]

Advice needed:

 

We’re the middle flat in a multi-occupancy building of three flats. There is no vent going out through the roof. There is an AAV in the bathroom in the flat above, and we have fitted an A1 AAV in our bathroom (all within the last 12 months). However, we are experiencing what I think is described in the thread above as a partial vacuum. We get considerable gurgling noises when both upstairs and downstairs flush their loo or release large amounts of water, and our waste drainage is very poor from our loo. 

 

CCTV has shown the shared stack is all clear and no problems on mains drainage. So it seems the issue (I think) is that there is no escape and vent for fowl air. 

 

Is it possible to vent (for outgoing air) from our middle flat? Has anyone experience of this? I presume were we to do this, we would need to extend external piping 900mm above upstairs’ window as per Building Regs. 

 

We already have an aperture in the external wall which vents steam from our windowless bathroom, so I’m wondering if I can use this hole in the external wall to vent outgoing fowl air. 

 

Any advice very gratefully received. 

 

Paul 

[Temp]

If its a partial vacuum your own AAV should be able to deal with it by opening to let air into the stack. That is assuming it in the right place on the pipework and not sealed into air tight boxing.

Edited February 13, 2021 by Temp

[Nickfromwales]

Can you upload a sketch of the waste pipework and show where your AAV is fitted? Also, you can get anti-siphon ( AAV ) traps for sinks and baths, so there may be some easier fixes available before you go to the lengths of adding a vent to atmosphere. 

[PaulJS]

Thanks for writing, both. 

 

AAV is next to the stack and at the foot of our bath. It’s a McAlpine A1 AAV. 

 

Best, 

 

Paul

 

[Nickfromwales]

What exactly is making the gurgling noises? 

[PaulJS]

In the first instance - from the trap under the bath - and we had water spitting up from the plug. We’ve since installed a waterless trap and now the gurgling comes from behind out toilet. 

[Dan F]

On 15/01/2020 at 20:29, joe90 said:

I think so, if I remember correctly ?, a loo flushing does not fill the 110mm pipe completely! If a bath is emptied the waste pipe is full but it will be 50mm max. My AAV is 50mm and I have had no probs in the last two years. Saying that, if I had room to extend the waste in 110mm pipe and use a full size AAV I would. My BC chap saw it and  said nothing.

 

Interesting.  Our plumber has done the same, but BRegs does seem to be clear that 75mm is the minumum for vent size for discharge stacks.  I see that 50mm AAV do exist, but I'd be concerned that the airflow rate supported by 50mm AAV is not going to be the same as a larger AAV, and there is therefore a higher risk of siphoning and breaking seals on basin (and smells/noises), even if you aren't having any specific issues with your setp. 

 

What size vent-pipe/AAV have others used, or seen used, for first-floor stack with toilet (i.e. not for branch with basins/sinks)?

Edited February 18, 2021 by Dan F

[joe90]

Use a full size if you can get it in but I couldn’t, B.I. Never passed comment, and it’s never caused a problem even with a house full.

[Gone West]

12 hours ago, Dan F said:

What size vent-pipe/AAV have others used, or seen used, for first-floor stack with toilet (i.e. not for branch with basins/sinks)?

I have a ground floor stack for a single toilet and basin that has a 50mm AAV and it's worked fine for three years and the BCO didn't say anything about it.

[WWilts]

On 24/09/2019 at 21:53, PeterW said:

some sink gurgling when a toilet in the extension is flushed but otherwise that is to regs. If it’s a problem then fit a couple of 32 or 40mm AAVs or anti siphon wastes to the basins.

New build in progress. External soil vent pipe.
If anti-siphon wastes are fitted to basins in each WC, does the WC require any other AAV?

[PeterW]

No as long as there is a vent stack higher than the water level in the highest WC

[Bonner]

Continuing this discussion ...

My plumber has installed an AAV about 1.2m above (first) floor level. I am going to box behind the toilet and sink but want the top around 900mm. Any problems dropping it 300mm, practical or regs? 

[Gone West]

13 hours ago, Bonner said:

Continuing this discussion ...

My plumber has installed an AAV about 1.2m above (first) floor level. I am going to box behind the toilet and sink but want the top around 900mm. Any problems dropping it 300mm, practical or regs? 

It depends on the height of the outflow pipe and the make of AAV. This document gives details, under installation section, for Floplast AAVs which I used.Floplast AAV info.pdf

[Bonner]

17 minutes ago, Gone West said:

It depends on the height of the outflow pipe and the make of AAV. This document gives details, under installation section, for Floplast AAVs which I used.Floplast AAV info.pdf

Excellent thanks! I will check what has been fitted and change it if necessary. It will stick out like a sore thumb where it is now 👍