Studor, a brand name air admittance valve, can solve venting problems when open air venting pipes will not work. Studor vents allow air to enter the pipes while keeping sewer gasses or odor from escaping. After a toilet flushes the increased water flowing down the drain creates a negative pressure. The negative pressure opens a valve in the Studor allowing air to enter the drain pipe. Once the air pressure has equalized the valve closes keeping the drain system sealed.
Things You'll Need
PVC tee fitting
PVC male fitting
Pipe thread compound
Cut the toilet drain line 2 inches off of the wall with a hacksaw. Use care to keep the cut square.
Install a tee fitting to the toilet drain line at the wall with PVC glue. The tee's port must face up.
Install the drain pipe from the tee to the toilet flange and the toilet flange with PVC glue.
Install a PVC reducer in the Tee's port with PVC glue. The reducer will change in size from the drain pipe's size, either 3- or 4-inch, to the Studor vent size, either 1 1/2- or 2-inch. The toilet specifications will determine the exact Studor model needed.
Install a section of PVC pipe that extends at least 4 inches above the weir in the toilet's trap into the tee. The weir, the last turn before the toilet water flows into the drain line, acts as a dam holding water in the trap. Cut the pipe with PVC cutters. This will often place the top of the Studor valve just under the toilet tank.
Install a PVC male fitting on the PVC pipe extending out of the reducer with PVC glue.
Cover the threads on the male fitting with pipe thread compound. The compound should cover the top half of the threaded area.
Thread the Studor valve onto the male fitting until its hand tight. Turn the valve one more full turn with a set of pliers. Remove any excess pipe thread compound from the male fitting with a rag.
Install the toilet, flush and check for leaks at the drain pipe and vent connections.
When gluing PVC, apply PVC glue to both the male and female ends of the connection.