Heat exchange ventilation system

Abstract

A heat exchange ventilation system includes: a heat exchange ventilator; a temperature adjustment coil disposed downstream of a heat exchange element in a supply duct and heating or cooling air passing through the supply duct disposed downstream of the heat exchange element; a return supply duct that returns the air in a room to a portion of the supply duct located upstream of the temperature adjustment coil; an air duct switching damper that switches between the supply duct, which takes in outdoor air, and the return supply duct; an outdoor air temperature sensor that detects the temperature of the outdoor air; a return air temperature sensor that detects the temperature of the air in the room discharged to the outside of the room; and a controller that controls the operations of the heat exchange ventilator, the temperature adjustment coil, and the air duct switching damper.

1 . A heat exchange ventilation system including a heat exchange ventilator, a supply air duct to supply outdoor air outside a room into the room, and an exhaust air duct to discharge air in the room to the outside of the room, the system comprising:
 the heat exchange ventilator including:
 a casing having an internal supply air duct and an internal exhaust air duct that are formed therethrough, the internal supply air duct being the supply air duct inside the heat exchange ventilator, the internal exhaust air duct being the exhaust air duct inside the heat exchange ventilator, the internal supply air duct and the internal exhaust air duct being independent of each other; 
 a supply blower provided in the internal supply air duct; 
 an exhaust blower provided in the internal exhaust air duct; and 
 a heat exchange element provided inside the casing to effect heat exchange between air passing through the internal supply air duct and air passing through the internal exhaust air duct; 
   a temperature adjusting coil disposed downstream of the heat exchange element in the supply air duct to heat or cool air passing through the supply air duct downstream of the heat exchange element;   a return air supply duct to return the air in the room to a portion of the supply air duct located upstream of the temperature adjustment coil;   an air duct switching damper to switch between the supply air duct and the return air supply duct, the supply air duct being an air duct for taking in the outdoor air;   an outdoor air temperature sensor to detect temperature of the outdoor air;   a return air temperature sensor to detect temperature of the air in the room that is to be discharged to the outside of the room; and   a controller to control operations of the heat exchange ventilator, the temperature adjustment coil, and the air duct switching damper.   
     
     
         2 . The heat exchange ventilation system according to  claim 1 , wherein
 the controller executes first switching control for placing the air duct switching damper in a position to switch from the supply air duct to the return air supply duct when the temperature of the outdoor air detected by the outdoor air temperature sensor and the temperature of the air in the room detected by the return air temperature sensor satisfy a predetermined temperature condition during a heating operation mode of the temperature adjustment coil for heating the air or during a cooling operation mode of the temperature adjustment coil for cooling the air.   
     
     
         3 . The heat exchange ventilation system according to  claim 2 , wherein
 the controller executes the first switching control when: the temperature adjustment coil is in the heating operation mode for heating the air; the temperature of the outdoor air detected by the outdoor air temperature sensor is lower than or equal to a predetermined first temperature threshold; and the temperature of the air in the room detected by the return air temperature sensor is lower than or equal to a predetermined second temperature threshold.   
     
     
         4 . The heat exchange ventilation system according to  claim 2 , wherein
 the controller executes the first switching control when: the temperature adjustment coil is in the cooling operation mode; the temperature of the outdoor air detected by the outdoor air temperature sensor is higher than or equal to a predetermined third temperature threshold; and the temperature of the air in the room detected by the return air temperature sensor is higher than or equal to a predetermined fourth temperature threshold.   
     
     
         5 . The heat exchange ventilation system according to  claim 3 , wherein
 the controller executes second switching control for restoring the air duct switching damper to a position to switch from the return air supply duct to the supply air duct, when a temperature difference between a set temperature of the temperature adjustment coil and the temperature of the air in the room detected by the return air temperature sensor becomes smaller than or equal to a predetermined temperature difference threshold after the first switching control is executed.   
     
     
         6 . The heat exchange ventilation system according to  claim 3 , wherein
 the controller executes second switching control for restoring the air duct switching damper to a position to switch from the return air supply duct to the supply air duct, when a predetermined time has elapsed since the execution of the first switching control.   
     
     
         7 . The heat exchange ventilation system according to  claim 1 , wherein
 when the temperature adjustment coil is either in a heating operation mode or in a cooling operation mode, the controller executes, on the basis of a current time and a predetermined time, first switching control for placing the air duct switching damper in a position to switch from the supply air duct to the return air supply duct, and second switching control for restoring the air duct switching damper to a position to switch from the return air supply duct to the supply air duct.   
     
     
         8 . The heat exchange ventilation system according to  claim 7 , wherein
 the controller executes the first switching control when the heat exchange ventilation system is in operation, and executes the second switching control when the current time is past the predetermined time.   
     
     
         9 . The heat exchange ventilation system according to  claim 2 , wherein
 the controller increases an air volume of the supply blower after executing the first switching control.   
     
     
         10 . The heat exchange ventilation system according to  claim 7 , wherein
 during a time elapsing after execution of the first switching control until execution of the second switching control, the controller is capable of switching control of the exhaust blower to arbitrary control and executing the arbitrary control, the arbitrary control being any of: control for stopping the exhaust blower; control for causing the exhaust blower to provide a smaller air volume than that before the execution of the first switching control; and control for causing the exhaust blower to maintain the same air volume as that before the execution of the first switching control.   
     
     
         11 . The heat exchange ventilation system according to  claim 7 , wherein
 during a time elapsing after execution of the first switching control until execution of the second switching control, the controller executes any one predetermined control of the exhaust blower among: control for stopping the exhaust blower; control for causing the exhaust blower to provide a smaller air volume than that before the execution of the first switching control; and control for causing the exhaust blower to maintain the same air volume as that before the execution of the first switching control.   
     
     
         12 . The heat exchange ventilation system according to  claim 1 , wherein
 the temperature adjustment coil is disposed downstream of the heat exchange element in the internal supply air duct.   
     
     
         13 . The heat exchange ventilation system according to  claim 1 , wherein
 the temperature adjustment coil is disposed at a portion of a downstream supply air duct located downstream of the internal supply air duct.   
     
     
         14 . The heat exchange ventilation system according to  claim 1 , further comprising a branch supply air duct branching off from the supply air duct at a portion of an upstream supply air duct of the supply air duct located upstream of the heat exchange ventilator, and allowing the upstream supply air duct to communicate with the room, wherein
 the air duct switching damper is a first air duct switching damper disposed at a portion of the upstream supply air duct of the supply air duct located upstream of the heat exchange ventilator, the first air duct switching damper switching between a first air duct and a second air duct, the first air duct being an air duct for taking in the outdoor air as the first air duct switching damper closes the branch supply air duct and opens the upstream supply air duct, the second air duct being an air duct for allowing a part of the upstream supply air duct located downstream of the branch supply air duct to communicate with the branch supply air duct so as to circulate the indoor air as the first air duct switching damper closes an upstream side of the upstream supply air duct, and   the second air duct is the return air supply duct.   
     
     
         15 . The heat exchange ventilation system according to  claim 1 , wherein
 the air duct switching damper is a second air duct switching damper disposed downstream of the heat exchange element in the supply air duct inside the heat exchange ventilator, the second air duct switching damper switching between a third air duct and a fourth air duct, the third air duct being an air duct for taking in the outdoor air as the second air duct switching damper separates a part of the internal supply air duct located downstream of the heat exchange element from a part of the exhaust air duct located upstream of the heat exchange element inside the heat exchange ventilator so as to open the part of the supply air duct located downstream of the heat exchange element inside the heat exchange ventilator, the fourth air duct being an air duct for allowing the part of the supply air duct located downstream of the heat exchange element inside the heat exchange ventilator to communicate with the part of the exhaust air duct located upstream of the heat exchange element inside the heat exchange ventilator so as to circulate the indoor air as second air duct switching damper closes a part of the supply air duct located downstream of the heat exchange element inside the heat exchange ventilator, and   the fourth air duct is the return air supply duct.   
     
     
         16 . The heat exchange ventilation system according to  claim 4 , wherein
 the controller executes second switching control for restoring the air duct switching damper to a position to switch from the return air supply duct to the supply air duct, when a temperature difference between a set temperature of the temperature adjustment coil and the temperature of the air in the room detected by the return air temperature sensor becomes smaller than or equal to a predetermined temperature difference threshold after the first switching control is executed.   
     
     
         17 . The heat exchange ventilation system according to  claim 4 , wherein
 the controller executes second switching control for restoring the air duct switching damper to a position to switch from the return air supply duct to the supply air duct, when a predetermined time has elapsed since the execution of the first switching control.   
     
     
         18 . The heat exchange ventilation system according to  claim 7 , wherein
 the controller increases an air volume of the supply blower after executing the first switching control.