A zone control system allows a single HVAC system to independently control the heating and cooling in more than one zone serviced by the system. It allows multiple thermostats to be connected for each zone. The most common zone control systems operate a series of motor controlled air dampers to regulate the flow of air into a zone, thus controlling the temperature in that zone.

A zoned HVAC will usually contain not only dampers for each zone air duct, but unless the system can modulate the damper positions to prevent excessive supply side air pressure, it will need to be equipped with a bypass air duct from the supply side to the return side. This is equipped with a barometric bypass damper that opens when sufficient pressure builds up on the supply side. An outside air duct can also be installed to utilize outside air to save energy. The outside air duct damper can be controlled by some zone controllers.