Cheater Vent - Air Admittance Valve

Camper_Jeff_&_Kelli wrote:
Get a better AAV valve, not the cheap one.

About 25 bucks.

This is the one I bought and still ran into issues, until I sealed it. When this valve didn't help I just sealed it up and made sure the sink drains were closed when not in use.

Rover_Bill wrote:
My AAV's (one at kitchen sink and one at bathroom sink) will occasionally jam open when dumping the full grey tank. ..

You probably have quite common case that main tank vent pipe is inserted few inches inside the tank.
That was common issue on some motorhome black tanks and develop procedure called "harpooning"
Hacksaw blade attached to long pole inserted via 3" drain pipe would allow cutting too long pipe inside the tank.
No clue how to do it on gray tank though.

My AAV's (one at kitchen sink and one at bathroom sink) will occasionally jam open when dumping the full grey tank. Simple maintenance is to unscrew the AAV and shake it until the internal rubber seal rattles. If it doesn't rattle then I stick a thin screw driver in the internal slots and bump the seal loose.

Get a better AAV valve, not the cheap one.

About 25 bucks.

bdpreece wrote:
Do you really think a manufacturer would spend one cent extra unless it was absolutely necessary?

Yes and that is pretty obvious when bureaucrats make building codes.
In USA we have lawyers dictating engine oil changes as Mercedes case from 2002 shows. :S
In my Sprinter conversion gray system I have no pipe vents and no P-traps with only 1/2" vent for gray water tank.
When you make sink/shower outlet going down to bottom of the tank- you can avoid P-traps.
Pipe vents are potential need when you have several sinks on the same pipe.

BB_TX wrote:

Freep wrote:
.............
Now I'm wondering, do I really need an AAV? I don't have one under the sinks in my house and they work ............

You have vent pipes to the roof in the walls of your house behind sinks to prevent the siphoning. That’s different than tank vents.

Yep. The air pushed ahead of the draining slug of water enters the tank and exits through the vent, along with the air that the water displaces. The air that follows behind the slug of water needs to come from somewhere other than through the drain p-trap.

I would consider running a vent from that point to the roof or semi lateral to the existing vent.

Freep wrote:
.............
Now I'm wondering, do I really need an AAV? I don't have one under the sinks in my house and they work ............

You have vent pipes to the roof in the walls of your house behind sinks to prevent the siphoning. That’s different than tank vents.

Do you really think a manufacturer would spend one cent extra unless it was absolutely necessary?

Agree with the others . You won't necissarily know which trap it drains if it happens , kit sink , bath sink or shower . You also won't smell it immediately , you may go to bed and wake up to it . They are cheap .