The exhaust system should be constructed so that a minor vacuum is created in the compost container to draw air into the unit and up the exhaust pipe. Odors might result if this vacuum disappears, if there are loose connections or if an emptying door or toilet seat is left open.

To check air paths:

• Make sure all connections are airtight and watertight.
• If necessary, use silicone as a sealant. Such a vent provides a good air supply and prevents air from being sucked back out of the composter and through the toilet stool, which could produce odors silicone or plastic duct tape to seal joints. The exhaust system should be constructed to seal joints.
• A make-up fresh air supply vent to the wall in the toilet room should be installed below the level of the toilet stool at the floor.

Note: If you install a makeup fresh air supply vent, there should be no other exhaust fans in the same room. The composter itself will suck all odors out of the room, so it replaces the customary bathroom vent fan.