Sewer smell with AAV

[aavquestion]

Hi all, would appreciate some help here. This is from an old house in the Netherlands. I often, not always, get sewer smells in the shower room upstairs. In the pic, the two pipes on the right are for a sink and a washer. The one in the middle of the pic is for the shower. As you can see, they are not vented outside, I have an air admittance valve on the left, downstream of the trap. The trap services the shower and washer (the sink has its own trap, though ultimately it flows into this trap as well).

I checked the AAV, it seems to move freely. Though with water running from the tap, it does not seem to create enough pull to open it. If I remove the AAV completely, then the hallway where this is located has a strong sewer smell. Not sure if the fact that two open pipes (shower & washer) share the same trap could be the problem?

I'm afraid I've reached the limit of my (few) plumbing skills!

Thanks!

 

[oz-plumber]

Depending on the length waste pipes before the trap, you may need and AAV on the upstream side of trap

 

[aavquestion]

Depending on the length waste pipes before the trap, you may need and AAV on the upstream side of trap

Thanks for the response oz-plumber! In terms of length of waste pipe, the shower (pipe in middle of pic) drain is directly above the ceiling. The sink (upper Y piece on the right) is about 2.5m of pipe, with its own trap under the sink. The washer pipe (lower Y piece on the right) is about 1.5m. When you suggest an upstream AAV, what location do you mean? In the pic I've added two possibilities, labeled 1 & 2. Or does the washer waste pipe need to have its own trap, say just before it hits the lower Y piece? Thanks again for the feedback, much appreciated!

 

[aavquestion]

Also wanted to mention that the most frequent sewer smell happens when using the sink, with sewer smell coming out of the shower drain. Not sure if that adds a clue to the puzzle

 

[Deleted member 120897]

Does the shower have a trap fitted?

 

[aavquestion]

Does the shower have a trap fitted?

No, the trap you see is the shower's trap. The middle pipe goes up through the ceiling, the shower drain is directly overhead.

 

[Deleted member 120897]

Reckon that’s your issue then, no trap, so the shower waste will act as a sort of vent, releasing odours into the room.

 

[aavquestion]

Reckon that’s your issue then, no trap, so the shower waste will act as a sort of vent, releasing odours into the room.

Thanks, but can you explain that a bit more? The middle pipe has the shower drain at the top, and then drops into the trap on the pic. Odours would have to come from the pipe downstream of the trap, right? It's like the trap is not doing its job - not sure why.

 

[Chuck]

I think it's likely that what you a smelling is not the responsibility of of the AAV in the picture but a build up of rotting nastiness (hair, soap, fat, etc.) in the shared pipework between the basin and shower. Needs cleaning out properly. Shower and basin should each have their own traps to prevent this problem.

It's not safe to remove AAVs and leave the pipe open. Sewer gas can contain significant amounts of methane and hydrogen sulphide which are both dangerous. Aerosols are another possible hazard.

 

[aavquestion]

I think it's likely that what you a smelling is not the responsibility of of the AAV in the picture but a build up of rotting nastiness (hair, soap, fat, etc.) in the shared pipework between the basin and shower. Needs cleaning out properly. Shower and basin should each have their own traps to prevent this problem.

It's not safe to remove AAVs and leave the pipe open. Sewer gas can contain significant amounts of methane and hydrogen sulphide which are both dangerous. Aerosols are another possible hazard.

Thanks Chuck. Yeah removing the AAV was just an experiment to see what would happen. I don't think the smell is build up crud though. Most of the piping from the trap up is relatively new. There are short sections above the floor that are old, and all the piping below the 90 deg turns under the trap.