Patent ID: 10001289

Abstract:
An apparatus and method for measuring or controlling the Outdoor Air Fraction (OAF) ratio through economizer or outdoor air dampers and cabinet to total system airflow and mixed-air humidity ratio and wetbulb temperature for HVAC equipment. An OAF exceeding the minimum regulatory requirements wastes energy and contributes to global warming. OAF is used to optimize economizer damper position either manually or automatically using an economizer Fault Detection Diagnostic controller and actuator to meet minimum outdoor airflow requirements. After the outdoor air damper position is optimized, the mixed-air humidity ratio and mixed-air wetbulb temperature are determined and used with the measured mixed-air drybulb and supply-air drybulb temperatures to evaluate evaporator airflow, cooling capacity, and heating capacity, and, if necessary, provide a visual or electronically-transmitted error code signal indicating maintenance requirements to check or correct economizer damper position, cabinet leakage, airflow, cooling or heating capacity, and/or other faults for the HVAC system.