Multi-zone air handling systems and methods with variable speed fan

Abstract

An air handling system for supplying one or more zones with airflow. The air handling system generally includes a cold air damper, a hot air damper, a fan, and a controller. The cold air damper is associated with the one or more zones, and is movable between an open position and a closed position. The hot air damper is also associated with the one or more zones, and is movable between an open position and a closed position. The fan is positioned upstream of the cold air damper and the hot air damper and operates at varying speeds to generate the airflow for the one or more zones. The controller modulates the speed of the fan to maintain the cold air damper in an approximately fully open position or an approximately fully closed position.

1 . An air handling system for supplying one or more zones with airflow, the air handling system comprising: 
 a cold air damper associated with the one or more zones, the cold air damper movable between an open position and a closed position;    a hot air damper associated with the one or more zones, the hot air damper movable between an open position and a closed position;    a fan positioned upstream of the cold air damper and the hot air damper, the fan configured to operate at varying speeds to generate the airflow for the one or more zones; and    a controller configured to modulate the speed of the fan to maintain the cold air damper in an approximately fully open position or an approximately fully closed position.    
     
     
         2 . The air handling system of  claim 1 , wherein the cold air damper and the hot air damper are linked such that closing the cold air damper opens the hot air damper and opening the cold air damper closes the hot air damper.  
     
     
         3 . The air handling system of  claim 1 , further comprising a variable speed drive configured to drive the fan.  
     
     
         4 . The air handling system of  claim 1 , wherein the controller is configured to increase the fan speed when the cold air damper is in the fully open position or the fully closed position.  
     
     
         5 . The air handling system of  claim 1 , wherein the controller is configured to decrease the fan speed when the cold air damper is positioned between the fully open position and the fully closed position and the fan speed is greater than a predetermined minimum value.  
     
     
         6 . The air handling system of  claim 1 , further comprising at least one zone temperature sensor associated with the one or more zones and configured to transmit a signal to the controller indicative of a temperature of the one or more zones, and wherein the controller is configured to increase the fan speed to maintain the temperature within a predetermined target temperature band.  
     
     
         7 . The air handling system of  claim 6 , wherein the controller is configured to decrease the fan speed if the temperature of the one or more zones is within the predetermined target temperature band and the fan speed is higher than a predetermined minimum fan speed value.  
     
     
         8 . The air handling system of  claim 1 , further comprising at least one neutral air damper associated with the one or more zones.  
     
     
         9 . The air handling system of  claim 1 , further comprising a cold deck positioned upstream of the cold air damper, and wherein the controller is configured to modulate the temperature of the cold deck based at least partially on the fan speed and the position of the cold air damper.  
     
     
         10 . The air handling system of  claim 1 , further comprising a hot deck positioned upstream of the hot air damper, and wherein the controller is configured to modulate the temperature of the hot deck based at least partially on the fan speed and the position of the cold air damper.  
     
     
         11 . A method of supplying one or more zones with airflow, the method comprising: 
 generating airflow with a variable speed fan;    routing the generated airflow to a cold air pathway and a hot air pathway, the cold air pathway including a cold air damper movable between an approximately fully open position and an approximately fully closed position, the hot air pathway including a hot air damper movable between an open position and a closed position; and    modulating the speed of the fan to maintain the cold air damper in one of the approximately fully open position and the approximately fully closed position.    
     
     
         12 . The method of  claim 11 , further comprising cooling air in the cold air pathway with a cold air deck and heating air in the hot air pathway with a hot air deck.  
     
     
         13 . The method of  claim 12 , further comprising mixing neutral air with the cold air from the cold air pathway and hot air from the hot air pathway.  
     
     
         14 . The method of  claim 12 , further comprising controlling the relative humidity of the one or more zones by altering the temperature of the cold air deck.  
     
     
         15 . The method of  claim 11 , further comprising increasing the fan speed when the cold air damper is in the approximately fully open position or the approximately fully closed position.  
     
     
         16 . The method of  claim 11 , further comprising decreasing the fan speed when the cold air damper is positioned between the approximately fully open position and the approximately fully closed position and the fan speed is greater than a predetermined minimum fan speed.  
     
     
         17 . An air handling system configured to supply airflow to one or more zones, each zone having an associated cold air damper and an associated hot air damper, the air handling system comprising: 
 a variable speed drive configured to turn a fan to generate the airflow for the one or more zones; and    a controller configured to modulate the speed at which the variable speed drive turns the fan based at least partially on a temperature of the one or more zones, and further configured to maintain the cold air damper in an approximately fully open position or an approximately fully closed position.    
     
     
         18 . The air handling system of  claim 17 , wherein the controller is configured to increase the speed at which the variable speed drive turns the fan when the temperature of the one or more zones is outside a predetermined temperature range.  
     
     
         19 . The air handling system of  claim 18 , wherein the controller is configured to decrease the speed at which the variable speed drive turns the fan when the temperature of the one or more zones is within a predetermined temperature range and the fan is turning at a greater speed than a predetermined minimum fan speed.  
     
     
         20 . The air handling system of  claim 17 , wherein each zone includes a neutral air damper and the controller is configured to adjust the speed at which the variable speed drive turns the fan based at least partially on the position of the neutral air damper.