Air admittance valve instead of vent stack

[Fazerruss]

As per tittle, question for the plumbers. I'm doing out my bathroom and due to the layout of the house build it has the soil vent stack inside the house which is boxed in. You can see it I the corner.

I'm toying with the idea of getting rid so could I fit an air admittance valve to replace the stack from the bog upward. I would fit it just above the branch T where the bog soil connects?
I would gain more space and not have box floor to ceiling but instead just a low boxed in area?

One of these...
https://www.toolstation.com/air-admittance-valve-110mm/p77893#full-desc

 

[Bobtail4x4]

it needs to be above the bath flood level

 

[Fazerruss]

it needs to be above the bath flood level

So just when the brown connection is in the pic?

 

[Kayos]

Make sure the sewer is ventilated somewhere else and make sure you can get access to it and you should be good

 

[Mikes]

Basin flood level if that goes to that stack.

 

[brightspark]

just above the height of the bog pan will do so if you flush and bog or pipe is blocked it will only fill to the top and overflow from there . soil stack out of roof is only fitted at the end of the system usually

 

[julianf]

A couple of threads running currently - one with people saying its best to do away with the auto air valve, and punch the stack through the roof, and then this one...

I have an auto valve here. Im about to change it again... I wish it went out through the roof where i didnt have to think about it.

 

[Kayos]

A couple of threads running currently - one with people saying its best to do away with the auto air valve, and punch the stack through the roof, and then this one...

I have an auto valve here. Im about to change it again... I wish it went out through the roof where i didnt have to think about it.

Every system is different, I recently added a vent to a system that shouldn't have needed it but it did, adding the vent stopped the downstairs toilet suffering from splashback

 

[hermetic]

I have used air admittance valves twice, and they both stuck on occasion, and when they stick, they tend to empty the lowest trap, and allow the pungent aroma of sewer escape into the room! refill the trap, put the plug in and flush the loo a few times till you hear the valve open, and all is well again, they do work, but they are better in theory than practice, and you still need a vent somwhere at the highest point of the system. I live in a terrace, and my neighbour shares the same drains and manhole, his bathroom is at the back of the house, and so he has an external soil stack and vent. My bathroom is at the front, and we had a plug ugly stack on the front, which I moved inside and fitted an AAV at the back of the cistern. Has the OP considered moving the toilet into the corner, fixing the cistern to a diagonal timber across the corner, and putting the AAV behind the cistern. Gets rid of the junction to the side and puts the WC pan direct into the soil pipe, and improves acces to the WC, thats what I did!
Phil

 

[Seadog]

An AAV needs to be 8" above the highest water level connected to the system. Remember that the stack pipe is to admit air to the drain, not to vent it, so if you do box the AAV in you should make sure that it can draw air from somewhere.

 

[MattF]

Every system is different, I recently added a vent to a system that shouldn't have needed it but it did, adding the vent stopped the downstairs toilet suffering from splashback

That last part tickled me.

 

[Kayos]

That last part tickled me.

I was trying to put it politely

 

[Agroshield]

An AAV needs to be 8" above the highest water level connected to the system....

I was interested to see where that number came from. I could not see it in Part H of the Building Regulations. It seems the controlling document for air valves is is BS EN 12380.

I did a little looking and located this:

https://bpfpipesgroup.com/media/29598/Air-admittance-valves-for-domestic-properties.pdf

downloadable from https://bpfpipesgroup.com/application-groups/building-services/

What is interesting in there is that there is a type of valve, designated 'Type A', that can be used below the flood level.

 

[Seadog]

I seem to recall reading it when I was considering doing away with my stack and fitting an AAV outside. I think it's under the WRASS regulations.

 

[Welderpaul]

An AAV needs to be 8" above the highest water level connected to the system. Remember that the stack pipe is to admit air to the drain, not to vent it, so if you do box the AAV in you should make sure that it can draw air from somewhere.

Like this?...

 

[brightspark]

i put one in our down stairs bog just the height of the bog seat. no need for any higher cos if it backs up the crap will overflow the rim of the pot . if the drains back up from the cesspit the bog flushes a bit slow and can be rodded before it gets that far

 

[julianf]

A couple of threads running currently - one with people saying its best to do away with the auto air valve, and punch the stack through the roof, and then this one...

I have an auto valve here. Im about to change it again... I wish it went out through the roof where i didnt have to think about it.

I keep getting notifications that this thread is active again.

To update on my own situation -

Roof was repaired. Auto admittance valve swapped to a stack.

Happy days.

 

[Fazerruss]

I decided to keep the stack but slim down the boxing in. It can also be removed for maintenance if necessary.

 

[dave h 2]

I decided to keep the stack but slim down the boxing in. It can also be removed for maintenance if necessary.

View attachment 462849

Is the reversing camera screen for backing away from the pan without hitting the sink or just to keep up with East Enders?
BTW wise move with keeping the stack

 

[RaceDiagnostics]

Like this?...

View attachment 462810

Similar to mine, zero comment from the building inspector.