Plumbing fixtures such as a sink or bathtub have a trap filled with water to prevent noxious gases from entering the home. The trap requires a vent that prevents the water from being pulled out of the trap, but allows the drain to flow freely. A Studor air admittance valve allows air to enter the drain pipe without a vent connection and is useful when a connection to a vent pipe is impractical or impossible. The valve allows air to enter the drain pipe and prevents gases from escaping.
Things You'll Need
- Teflon tape
- 1 1/2-inch female-threaded Tee fitting
- Slip-joint pliers
- 1 1/2-inch PVC pipe
- PVC primer
- PVC cement
- Two, 1 1/2-inch male-adapter fittings
- 1 1/2-inch 90-degree elbow fitting
- Two, 1 1/2-inch female-adapter fittings
- Threaded male-trap adapter
- Torpedo level
Wrap Teflon tape around the PVC trap adapter threads. The trap adapter is the fitting attached to the drain pipe that exits the wall under the sink. Screw the threaded PVC Tee fitting onto the trap adapter until it is tight, then turn it enough to point either left or right. Use the slip-joint pliers to turn the Tee fitting if necessary.
Cut a piece of PVC pipe long enough to reach from the Tee fitting to the left or right edge of the sink. Open the PVC primer can and wipe the dauber attached to the lid around both ends of the pipe to apply the primer. Dip the dauber into the primer after each application. Apply primer to the inside of the male adapter fitting and to the inside of the 90-degree elbow fitting.
Open the PVC cement can and withdraw the dauber. Wipe the dauber around one end of the pipe and around the inside of the male adapter fitting. Put the adapter fitting over the cemented end of the PVC pipe and turn it one-quarter turn. Hold the fitting in place for 30 seconds. Repeat this step for the 90-degree elbow fitting and the other end of the pipe.
Cut a 1 1/2-inch long piece of PVC pipe. Apply primer to the ends of the pipe and the inside of the second male adapter fitting. Apply cement to the other end of the 90-degree fitting and one end of the 1 1/2-inch long pipe. Fit the cemented pipe end into the 90-degree fitting. Apply cement to the opposite pipe end and the inside of the second male adapter fitting, and fit them together.
Wrap the threads on the male adapter fitting at the end of the longer pipe with Teflon tape. Screw the fitting into the left or right facing threads on the Tee fitting until it is tight. Turn the pipe an additional turn to point the short piece of pipe and male adapter up.
Cut a 4-inch long piece of PVC pipe. Prime both pipe ends and the inside of two female adapter fittings. Cement a female adapter fitting onto each end of the pipe. Wrap the threads on the Studor air admittance valve with Teflon tape. Screw the valve into one of the female adapters until it is hand tight.
Wrap the threads on the male adapter fitting attached to the 1 1/2-inch long piece of pipe with Teflon tape. Screw the female fitting on the 4-inch long piece of pipe onto the male adapter until it is tight. Use the torpedo level to ensure the pipe is vertically level, and adjust the Tee fitting or long pipe with a pliers if necessary.
Wrap the threads of the male threaded trap adapter with Teflon tape and screw it into the Tee fitting until it is hand tight, then turn it an additional one-half turn with the pliers. Install the trap assembly to the sink drain and the trap adapter per the manufacturer's instructions.
Tips & Warnings
- The 4-inch long pipe must be within 15 degrees of vertically level or the valve will not work properly. It does not have to be perfectly level, but should be close.
- The fumes from the cement and primer are hazardous in small, enclosed areas. Keep the covers screwed on the cans whenever you are not using them and read the safety instructions before use.
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