My house is an older built home with no main vent. I've recently updated the house trap and everything is air tight now causing toilet to not flush. My bathroom sink is a double vanity sink set up with each sink having their own drain pipe. If I unhook one after the trap , my toilet flushed fine with out back up. Can I add an AAV there am treat that line as the vent since it's working for the small plumbing set up my house does have. Figured I would tie the double sink drains together into one line and utilize the drain that's open now as the vent for the bathroom and kitchen sink ? I installed an AAV today but it was near the sink line and I don't think I set it in the proper spot as it did nothing for me so I unhooked the bathroom sink drain for now again. Any suggestions . I know the right thing is to add a main vent but my house is set up funny to the point running a pipe out the roof would be difficult.



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An AAV allows air into the drainage piping. A vent allows air to enter and exit the drain piping. You need air to exit the drainage piping and this is accomplished with a true vent above the roof.

Is it easier to run a main vent out the side of the house and up the exterior and to the roof line

You will see it on the outside of the house but atleast you have an actual atmospheric vent