The other uses a mechanical vent known variously as an air admittance valve (AAV), Studor valve or “cheater” valve. So which method is better? Myles Robinson, a home renovator, prefers the AAV ...

In the plumbing vent diagram above, window framing prevents the installation of a vent line, so an AAV is installed instead. As the fixture drains, the one-way valve opens to balance the negative ...