Air admittance valves (AAVs) are the most controversial devices introduced into plumbing in the past
century (maybe even the last millennium).
Plumbers either hate them or love them. There seems to be no middle ground. Those who hate air
admittance valves flood me, my editor and our publisher with e-mail, letters and nasty-grams. I guess if
you hate them, you really hate them.
So why mention air admittance valves and risk the possibility of being cursed, yelled and screamed at?
The plumbing engineers issued a position statement supporting air admittance valves. The American
Society of Plumbing Engineers published it Oct. 30, 1999, but that hasn't put an end to the rumors and
debate about AAVs.