A system for conveying air from one location to another includes a soft duct having a passage and an air flow control device. The air flow control device can be operated to vary a cross sectional area of a portion of the passage of the soft duct.

Provided is an easy-to-design, inexpensive air-conditioning apparatus in which an external static pressure and an airflow are calculated without using a static-pressure detector and an indoor-unit-side fan is controlled using those values. An air-conditioning apparatus according to the present invention is configured such that a control unit (indoor-unit-side control unit) stores an external static pressure of an indoor unit calculated from a rotation speed of an indoor-unit-side fan when the airflow of the indoor-unit-side fan is controlled to a predetermined rated airflow and controls the rotation of the indoor-unit-side fan so that the external static pressure of the indoor unit obtained thereafter from the rotation speed of the indoor-unit-side fan approaches the stored external static pressure.

An independent monitoring system and method for measuring the airflow rate in an appliance and determining its sufficiency is provided. An airflow detection system that monitors airflow rate (velocity) in an appliance is separate from the primary appliance control system and can determine whether a sufficient flow of air through air passageways occurs during operation of the appliance. An appliance component or subsystem can be controlled (e.g. activated or deactivated) by the airflow monitoring system based on the detected airflow rate.