Patent ID: 8483883

Claim:
A variable-air-volume heating, ventilating, and air conditioning system, comprising: a duct system; a supply fan integral with the duct system; a plurality of terminal boxes integral with the duct system, with the plurality of terminal boxes having a corresponding plurality of air inlet openings, and with the plurality of terminal boxes for supplying air to a corresponding plurality of zones within a building; a plurality of static pressure sensors, with each static pressure sensor located within a different air inlet opening out of the plurality of air inlet openings, and with each static pressure sensor for measuring an inlet static pressure associated with a terminal box; a plurality of static pressure setpoints, with each static pressure setpoint associated with a different air inlet opening out of the plurality of air inlet openings, and with each static pressure setpoint equal to a minimum static pressure rating of a different terminal box out of the plurality of terminal boxes; a programmed supply fan controller in communication with each of the static pressure sensors, said programmed supply fan controller for determining a setpoint error associated with each measured inlet static pressure associated with a terminal box, with the setpoint error equal to the difference between the measured inlet static pressure and the static pressure setpoint associated with the air inlet opening of the terminal box, and with said programmed supply fan controller selecting a minimum setpoint error out of all of the setpoint errors and converting it to an analog signal for use in modulating speed of the supply fan; whereby the modulated fan speed supplies a volume of air to a zone within the building that has a demand for air that is greater than any other zone in the building, with the volume of air not being greater than necessary to satisfy the minimum static pressure rating for the terminal box servicing said zone of greatest demand.