Looking Good Air Admittance Valve For Washing Machine Drain

Ive read a bunch of threads on problems people have with washing machine water backing up around the drain stack.

Air admittance valve for washing machine drain. Step 3 Install an Air Admittance Pipe AAP if it is inconvenient or too expensive to install a regular vent pipe. When water and waste move down a drain line it creates negative air pressure in the pipe. When these standpipes have a vent that terminates to an air admittance valve the water cannot rise in the vent pipe.

When properly installed an air admittance valve in the system is equivalent to an open vent pipe having the same cross sectional area as any other vent. In particular the posts by hkstroud and speedball1 have been very informative. Stack-type air admittance valves shall be located not less than 6 inches 152 mm above the flood level rim of the highest fixture being vented.

- AAVs are not permitted by certain municipalities to be used on a fixture that uses a pump to discharge waste water. It also has a trap before going under the floor. Some drains have an air admittance valve instead of a vent.

When the negative pressure ceases the sealing washer falls back in place. If the discharge is 21 gpm the flow exceeds the limitation of the 2-inch drain. - The 2 washing machine drain needs to connect into a 3 line.

This negative pressure lifts the sealing washer and lets air in which allows the waste to drain away freely. The washing machine sends water into that drain under quite a bit of pressure and you want air moving freely through the pipe. When the negative pressure builds up enough in the drain pipe if there were no means to equalize the pressure then that pressure would back-siphon the water in the trap into the waste piping.

I have a 1 12 pvc drain stack that is above the height of the washer. In this video I talk about a cheater vent that is sometimes used in plumbing systems. It runs through floor then horizontal where it connects to an older cast iron.