Stink from kitchen grey tank
We leave a bowl in our kitchen sink. Since the REALLY hot (100F) weather has arrived, we get this awful smell coming from the sink hole drain whenever we lift the bowl away. It's as if the p trap is n...
Forum Discussion
ice2fire wrote:
Why does the tank need air going INTO it ? I would have thought that as waste water went INTO the closed tank, air would need displacing.
Physics at work.
The tank itself is vented (open to both directions) to the roof. The air admittance valve is to let the pipe to the tank drain when the water flow from the sink or whatever stops without siphoning the water out of the trap; it's basically a vacuum breaker. It doesn't (or at least shouldn't) let air out because you don't want to have smelly sewer gasses from the tank in your kitchen.
You do need to let air into the tank when dumping the tank. The roof vent is primarily responsible for that.
These are not uncommonly used in normal household plumbing for the same purpose. An alternative is to vent from the traps to the roof vent if that is physically reasonable.
