I have attached a rough diagram of what I think the venting in the house is like.
There is a problem in that the upstairs toilet is being siphoned when the sewage ejector downstairs goes.
However, the toilet water is not going into the pump, it goes to a septic tank through gravity. So, I can only assume that the toilet and the ejector pump use the same exit pipe otherwise the water would not be siphoned off.
Once the toilet has been siphoned low, then the sink in the upstairs bathroom also starts to gurgle.
Traps on the ground floor seem to be ok even though I don't think they are all vented properly. There could be hidden AAVs but I'm not sure. The only one I can see is hidden in the wall space behind the diswasher.
There is no other main vent exiting the house apart from the one from the sewage tank.

How can I fix the venting in the bathroom so that the toilet and sink do not gurgle? Can I just take a pipe from underneath the sink to outside?
Should the sink and the toilet be on the same waste line?

 

I would start by reworking the plumbing under the 2nd floor sink and add in an AAV at that point. If you were redoing the bathroom, it would be a good time to install a real atmospheric vent, but it'll be a pain without redoing some sheetrock and such.

[ATTACH=CONFIG]63060[/ATTACH]

That should solve your issues.

 

I'll try it. Problem is that the pipe is directly under the sink outlet so I have to make some odd shapes?

 

Something like this or is there a better way to arrange the pipe?

 

I'd suggest cutting up and throwing away all that glued up mess and going with slip fittings. They are a lot easier to work with. Your suggestion is a good way. Use two sanitary Els and a sanitary Tee.



The cut line may need to be lower. I just guessed in the image.

 

must there be a slight down angle on the run into the bottom of the sanitary or can it be a flat pipe to get back to centre and then a pipe straight down?

 

because it's such a short run (6-8 inches at most), I wouldn't worry if either of the runs are flat or near-flat. You definitely don't want them pitched backwards, but a flat run for a short bit won't cause any issues.

 

must the AAV be a certain distance above the tee, ie add in some extra pipe or can I plug it directly into the T join?

 

Minimum 4" above the horizontal part of the drain pipe. Generally you want to install them as high as is possible... not just the minimum.

 

Do any of the curved fittings need a cleanout access?
For example, the existing s bend has some kind of screw in hole on the bottom of one of the pipes.

 

Unsure what Canadian code is. But in Zorfdt's photo, a union style trap usually qualifies as a cleanout because of the ease with which it can be taken apart and snaked. Glued traps usually need a cleanout on bottom, as it sounds like you have. In your case, there would be nothing wrong with adding a cleanout as part of a vertical wye or tee just below the aav. But someone who knows Canadian code could surely give a better answer.

 

The AAV I have is a 20 DFU that screws into a 2inch thread.
However, the waste pipe I have to couple to is a 1.5 inch
Is there such a thing as a 2inch threaded built into a reducer so that I don;t have to buy any 2 inch PVC pipe.

 

I added the plumbing, primed and glued all parts, quarter turn on assembly for each part, and put tape around the threads on the AAV.
The water part of the plumbing is working
However, there is now a sewage smell within the cabinet.
Could the new AAV really be faulty? How can I tell or how can I tell if there is an air gap in one of the PVC parts?

Secondly, it has stopped the traps from being siphoned but when the sewage pump goes, I can still see the toilet bowl water move a bit, just nowhere near as much as before so maybe the `wet vent through the 1.5inch pipe isn;t enough air for the system?

 

bump (25 character minmum) bump bump bump

 

It would be pretty easy to unscrew the AAV and screw in a square plug and see if the smell goes away. Obviously you should have a non hardening sealant on those threads. Can't tell if you purple primered and glued each joint... one reason to use WHITE schedule 40, not black. Maybe it's the picture but that bottom connection (and the tailpiece connection) looks a bit off. And it's not part of the question, but you have created an S trap there. You need a drain arm that is 2x the length of the p trap (horizontal) before it meets your sanitary tee. (At least in the US) Really can't say much about Canucks codes.

 

X, the black pipe is ABS plastic and does not require any primer when cementing the joints.

You MAY be right on the length of the trap arm being a component of an S trap but it is news to me. S traps are traps that have NO venting.

 

I thought it looked too shiny to be abs... thought maybe black schedule 40 was a Canadian thing. No one uses ABS around here for plumbing... and if they do, the abs is dull black, not shiny. Could have sworn an S trap was bad because of the siphoning, regardless of whether or not there was a trap.... that the length of the trap arm is what breaks the siphon within the trap.... until the point at which it spills over into the sanitary tee and gets vented. But I'm no plumber.

 

ABS can be shiny or dull, depends upon the manufacturer. ABS is pretty common in my area although PVC is making inroads.

 

But I have to create an area for the wet venting, so it's always going to be a kind of s trap? Or do I need more space in the vertical portion? The p trap is there, goes into a T and then immediately down again, so the water shouldn't be siphoned if it stays in the p trap area? An s trap is like the top picture in the thread?
I primed and glued everything about from the AAV, which is threaded. Will try blocking it with duct tape as that's all I have for now. There is only PTFE tape on the threads.
It's all black schedule 40.

 

The horizontal part is what I was suggesting could have been longer. A longer section of horizontal pipe between the sanitary tee and elbow. I highly doubt its a problem, like furd said, its now vented.

 

You'll always see the water in the toilet move a bit whenever there's a lot of water moving. Even with vents, there's still a bit of a pressure change (fluid dynamics and such), so that's nothing to worry about.

Your setup looks reasonable to me. I don't see any reason that the p trap is being siphoned. To me, it even looks like a deeper than usual P-trap (which again, I don't see as an issue).

I like X Sleeper's suggestion of temporarily changing the AAV out with a plug to confirm the smell is coming in fact from that point. I wouldn't expect the AAV to be defective out of the box, but it's always possible.

 

My vote is for a defective AAV.

 

I tested the AAV in reverse (as it would for air pressure in the system) and it didn't let any air out.
Maybe the threads are defective or don't fit well. I could put more PTFE tape on to try. At this stage, thinking I have to just redo all the pipework as can't be sure where the leak is.

 

I assume that you "tested" it by first removing the AAV and then blowing into the threaded end. Just because it seals when pressurized does not mean it seals when subjected to normal pressure. Rather than use additional wraps of tape I would use a paste-type Teflon thread sealant. The paste works far better than the tape. You don't needs gobs of paste, only enough to fill the bottom of the threads and about two or three threads in length. Try to avoid the first two threads.

 

Ok, pipe cap on for 12 hrs = no smell.
AAV back on with pipe dope been on for 2 hrs now = smell.
Could be the AAV not sealing again properly after it has sucked air through?

 

SOLVED - thanks all!
Fitted new AAV and no problems now.
Can only presume the previous one was dropped or damaged.