A general issue in plumbing remodeling is figuring out how to run fresh vent lines when access to the existing drain-waste-vent system is stopped by some structural element. It may seem like all hope is lost, but do not let that little roadblock get in the way of your dream kitchen makeover. One solution can be an AVV, or air admittance valve.

These control devices are gravity-operated gadgets that react to the force of draining water and open to let air in. When not draining gravity forces the seal and locks the valve, keeping sewer gases out of the room. Depending on the size of the valve and vent, AAVs can support different vent lines. Local codes govern the use of AAVs in location of vents.