Return fan control system and method

• Main Author: CLANIN THOMAS J
• Format: Patent
• Language: English
• Published: 04.12.2012
• Subjects: AIR-CONDITIONING, AIR-HUMIDIFICATION, VENTILATION, USE OF AIRCURRENTS FOR SCREENING; BLASTING; CONTROL OR REGULATING SYSTEMS IN GENERAL; CONTROLLING; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; HEATING; LIGHTING; MEASURING; MECHANICAL ENGINEERING; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS ORELEMENTS; PHYSICS; RANGES; REGULATING; SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES; TESTING; TESTING STATIC OR DYNAMIC BALANCE OF MACHINES ORSTRUCTURES; TESTING STRUCTURES OR APPARATUS NOT OTHERWISE PROVIDED FOR; VENTILATING; WEAPONS

A return fan control system for an HVAC system comprises a supply fan control loop, a return fan control loop and a building pressure control system. The supply fan control loop comprises a duct pressure controller arranged to control a supply fan to a duct pressure setpoint. The return plenum pressure control loop comprises a return plenum pressure controller arranged to automatically control a return fan to a return plenum pressure setpoint determined by a setpoint reset function. The building pressure control system is operable to control a building pressure. The building pressure control system may comprise a building pressure control loop and an outside air control loop cooperatively arranged to control an exhaust damper in response to an outside air intake.