Hvac system, a controller therefor and a method of measuring and managing ventilation airflow of an hvac system

Abstract

A controller, an HVAC system employing the controller and a computer programmable product to implement a method of measuring and managing ventilation airflow of an HVAC system is disclosed. In one embodiment, the controller includes: ( 1 ) an interface configured to receive feedback data from the HVAC system, the feedback data corresponding to a pressure difference across the outdoor damper and an economizer damper position and ( 2 ) a ventilation director configured to determine a ventilation airflow rate of the HVAC system based on the pressure difference, the economizer damper position and economizer ventilation data of said HVAC system.

What is claimed is: 
     
         1 . A controller for a heating, ventilating and cooling (HVAC) system having an economizer with an outdoor damper, comprising:
 an interface configured to receive feedback data from said HVAC system, said feedback data corresponding to a pressure difference across said outdoor damper and an economizer damper position; and   a ventilation director configured to determine a ventilation airflow rate of said HVAC system based on said pressure difference said economizer damper position and economizer ventilation data of said HVAC system.   
     
     
         2 . The controller as recited in  claim 1  wherein said ventilation director is further configured to adjust a position of said economizer based on said economizer damper position and a desired ventilation airflow rate. 
     
     
         3 . The controller as recited as recited in  claim 1  wherein said ventilation director is configured to determine said ventilation airflow rate based on said economizer ventilation data, said pressure difference, said economizer damper position and a supply airflow rate of said HVAC system. 
     
     
         4 . The controller as recited in  claim 3  wherein said economizer ventilation data is developed based on measured data obtained while operating said HVAC system over multiple operating conditions during manufacturing or engineering thereof. 
     
     
         5 . The controller as recited in  claim 1  wherein said economizer has a single damper assembly. 
     
     
         6 . The controller as recited in  claim 1  wherein said economizer damper position indicates a blade angle of said outdoor damper and is based on a feedback signal from an actuator of said economizer. 
     
     
         7 . The controller as recited in  claim 6  wherein said ventilation director is further configured to compensate for hysteresis between said feedback signal and an actual position of blades of said outdoor damper. 
     
     
         8 . The controller as recited in  claim 1  wherein said ventilation director is further configured to employ an outside air temperature and an elevation associated with said HVAC system to determine said ventilation airflow rate. 
     
     
         9 . The controller as recited in  claim 1  wherein said ventilation director is configured to select data from said economizer ventilation data to calculate said ventilation airflow rate based on said economizer damper position. 
     
     
         10 . The controller as recited in  claim 1  wherein said ventilation director is further configured to determine a prorated ventilation rate based on said ventilation airflow rate. 
     
     
         11 . The controller as recited in  claim 1  wherein said ventilation director is further configured to generate an alarm or a status of said economizer based on said feedback. 
     
     
         12 . A computer program product, comprising a non-transitory computer usable medium having a computer readable program code embodied therein, said computer readable program code adapted to be executed to implement a method of measuring and managing ventilation airflow of a heating, ventilating and air conditioning (HVAC) system having an economizer with an outdoor damper, said method comprising:
 receiving feedback data from said HVAC system, said feedback data corresponding to a pressure difference across said outdoor damper and an economizer damper position of said HVAC system;   applying said pressure difference and said economizer damper position to economizer ventilation data representing ventilation airflow rates of said HVAC system; and   determining a ventilation airflow rate based on said applying, wherein said ventilation airflow rate corresponds to one of said ventilation airflow rates of said economizer ventilation data according to said pressure difference and said economizer damper position.   
     
     
         13 . The computer program product as recited in  claim 12  wherein said method further comprises receiving a desired ventilation airflow rate and adjusting a position of said economizer based on said economizer damper position and said desired ventilation airflow rate. 
     
     
         14 . The computer program product as recited in  claim 12  wherein said economizer ventilation data is developed based on measured data obtained while operating said HVAC system over multiple operating conditions during manufacturing or engineering thereof. 
     
     
         15 . The computer program product as recited in  claim 12  wherein said economizer damper position indicates a blade angle of said outdoor damper and is based on a feedback signal from an actuator of said economizer. 
     
     
         16 . The computer program product as recited in  claim 15  wherein said method further comprises compensating for hysteresis between said feedback signal and an actual position of blades of said outdoor damper. 
     
     
         17 . The computer program product as recited in  claim 12  wherein said determining further includes employing a supply airflow rate of said HVAC system. 
     
     
         18 . The computer program product as recited in  claim 12  wherein said method further includes determining a prorated ventilation rate based on said ventilation airflow rate. 
     
     
         19 . A heating, ventilating and cooling (HVAC) system, comprising:
 an economizer having an outdoor damper and an actuator to move blades thereof;   a pressure sensor configured to determine a pressure difference across said outdoor damper; and   a controller, comprising:
 an interface configured to receive feedback data from said HVAC system, said feedback data corresponding to said pressure difference and an economizer damper position; and 
 a ventilation director configured to determine a ventilation airflow rate of said HVAC system based on said pressure difference, said economizer damper position and economizer ventilation data of said HVAC system. 
   
     
     
         20 . The HVAC system as recited in  claim 19  wherein said ventilation director is further configured to adjust a position of said economizer based on said economizer damper position and a desired ventilation airflow rate.