AAV factors affecting operation

[GAZG123]

After having a new roof fitted I opted for getting a clean roofline and having an aav fitted to the shortened soil stack in the loft. Since doing so we seem to be getting foul smells around the bathroom and downstairs in the kitchen whereas when the stack vented through roof it was fine. I wondered what the best way to check is aav is working properly, empty full bath and listen to see if valve is opening to equalise negative pressure? One other thing that I am thinking may affect this is I have a seperate pump from my boiler where condensate is pumped up about 3 metres from boiler in upstairs bedroom to a tee in soil stack about 1metre below aav, it has a nonreturn valve on it i wondered if it would have any effect on operation of aav.

 

[ShaunCorbs]

You need to have at least one vent on your house if that’s the only one best get the roofers back

 

[GAZG123]

You need to have at least one vent on your house if that’s the only one best get the roofers back

 

[GAZG123]

Thanks Shaun, but roofers shortened stack to leave it in loft and put an aav on it.

 

[ShaunCorbs]

Need to vent externally sorry to say

 

[GAZG123]

Need to vent externally sorry to say

Need to vent externally sorry to say

Right is this a regs thing... to be fair it was OK before dropping it down, seems to be a fair bit of work to put it back through roof , would I be able to angle it out through side wall as it is quite close or better off straight up?

 

[ShaunCorbs]

Yes it’s regs as you have problems like your having now and depending on how your neighbours are vented you maybe effecting them also

Best to go through the roof but aslong as it vents externally with no windows or vented soffits close your ok

 

[GAZG123]

Yes it’s regs as you have problems like your having now and depending on how your neighbours are vented you maybe effecting them also

Best to go through the roof but aslong as it vents externally with no windows or vented soffits close your ok

That's great thanks for your help.

 

[Ric2013]

If other houses on your drain run have an open vent, then you might not need an open vent yourself depending on the situation, but really this should have been considered by Building Control at the time of modification. It wasn't; no point crying over spilt milk, but Shaun is right as YOU may have been the open vent for your neighbours.

If another house is at the head of the sewer and there is an open vent there, and therefore we'll assume you don't need an open vent for the purposes of the following suggestion, it may be that there was already a problem with your house's waste pipes or soil and vent and the lack of open venting is now making this more apparent.

It may be worth, in any case, doing a basic industry-standard airtightness test (3 minutes at a low pressure) to see if there's an obvious hole on the drain. Doing this test to my own house revealed a total lack of airtightness of the system and I eventually located a 20mm hole that someone had drilled into the soil and vent hidden in a wall cavity (which explained why I couldn't find anything wrong with any of the exposed pipework) , so anything is possible!

 

[oz-plumber]

Right is this a regs thing... to be fair it was OK before dropping it down, seems to be a fair bit of work to put it back through roof , would I be able to angle it out through side wall as it is quite close or better off straight up?

It would be better to vent the pipe through the side wall to open atmosphere than to leave the AAV in the ceiling space.

Regs may differ, and some may stipulate that the vent has to go through roof or above building line.
It's not a life threatening situation, so i wouldn't be concerned where the vent terminates as long as it is to open air and away from windows.

Incidently, you sewer smells are probably coming from the positive pressure created by flushing toilets that are pushing air through traps. AAV's don't allow for positive pressure. So that positive air pressure has to relive itself somewhere.

 

[GAZG123]

It would be better to vent the pipe through the side wall to open atmosphere than to leave the AAV in the ceiling space.

Regs may differ, and some may stipulate that the vent has to go through roof or above building line.
It's not a life threatening situation, so i wouldn't be concerned where the vent terminates as long as it is to open air and away from windows.

Incidently, you sewer smells are probably coming from the positive pressure created by flushing toilets that are pushing air through traps. AAV's don't allow for positive pressure. So that positive air pressure has to relive itself somewhere.

Cheers for that, big help, do you think it would be an issue if I put a right angle bend onto 110mm pipe then reducing it to 82mm to take it about 1 metre through outside wall in attic then putting a vent cap straight on pipe where it is outside or should I put an elbow on first so it is vertical or do I have to take it above roofline, it would be about 3 metres from the top of the bathroom window sideways?

 

[Ric2013]

As long as you're 3 horizontal, I can't really see a problem. Nor can I see a problem with reducing to 82 on the dry part of the stack.