I just wanted to ask a quick question to anyone willing to reply.

We are living in a house that had a dyi reno done in which the kitchen sink was not vented. When it is drained it would actually squirt water out of the bathroom sink. I have since plumbed in an in- line vent (mechanical spring style) which doesn't open when the drain is pulled.

I have read these mechanical vents are not allowed but I still seem to find them for about $9 Canadian at the home depot. Is the answer an Air admittance valve instead? What is the difference (other than $30 dollars in price) between the two.

Also when I leave the mechanical valve off the six inch pipe stub water comes out of the "vent" hole. Will this be a problem for an aav if I put one on in the future.

I hope you can help

Thanks Mike

I recommend only the Studor AAV. Master plumbers will always frown on these because they're mecanical. Vent stacks are the best way to go, but in a pinch where it's needed, I rec the aav. Don't go cheap on this type of vent.

Sounds like you may have a clogged drain. Is the fall [pitch downward] good?

You can thank Doug for this explanation. The inline vent is the cheap black plastic ones used in mobile homes. It is a simple spring check valve with a rubber disk. It costs about 5 bucks. The studor and oatey which costs about 25 bucks is kind of mechanical in that it has a little ball that blocks the port and is approved by the building code.
Thanks Doug, Tom