odor 12 plumbers can't fix

Moderator Post (s) for this thread: > Questions: by homebild on 04/22/2008 > House Trap by homebild on 04/22/2008 > House Traps are Largely Prohibited by homebild on 04/22/2008 > A few things by Handyman on 05/05/2008 > Smoke Test by Handyman on 05/06/2008 > These valves by Handyman on 05/06/2008 > Washing machine drain by Handyman on 05/08/2008 > The toilet or sink nearest the by Handyman on 05/08/2008 > Glad to hear by Handyman on 05/19/2008

I have no sump pump, no plumber in city has a smoke box, apparently that is old school and no one does this anymore, so they got rid of the boxes.

Where do i find an air admittance valve? Could my air exchanger have anything to do with this?