Extreme Veteran
Posts: 379
Location: Missouri | Yes you need to stack vent the gray tank. The air in the tank has to have some place to go as water comes in. The little hole next to your water inlet door, that's the vent for the fresh water tank. It's to let air out when you fill the tank and allow air in as the pump draws the water level down. The under sink vent is a one way vent to prevent water suction from emptying the p-trap, it does not allow air to escape the holding tank. |