Patent ID: 7625277

Claim:
An air-pressure control system, the system comprising: a self-contained unit housing extending through a structural opening in a wall of a building; a system inlet in a first sidewall of the housing; a system outlet in a second sidewall of the housing, which is opposite to the first sidewall; a first filter located within an airflow path between the system inlet and system outlet; a variable-speed fan configured to operate at a speed, the variable-speed fan being reversible; a motor controller in communication with the fan and configured to control the speed of the fan; a differential-air-pressure transducer configured to monitor an air pressure differential between the system inlet and the system outlet; a closed-loop controller in communication with the motor controller and the differential-pressure transducer, wherein the closed-loop controller is configured to vary the speed of the fan based on the pressure differential between the inlet and outlet of the system, thereby controlling a pressure within a space; and a control panel provided on the housing in communication with the closed-loop controller and configured to receive setpoint values and to change the speed or a direction of the fan based on the setpoint value; wherein the control panel includes a switch having a positive pressure position and a negative pressure position, the fan operating in a first direction to create a controlled substantially constant positive pressure within the space when the switch is in the positive pressure position, the fan operating in a second direction to create a controlled substantially constant negative pressure within the space when the switch is in the negative pressure position.