Hvac system with centralized control connected to a fresh air ventilation system

Abstract

A ventilation system that does not communicate via proprietary communication protocol can be integrated with an HVAC system that does use the proprietary communication, and the ventilation system can draw in fresh air at optimized times. For example, the ventilation system can include an air-handling-unit (AHU) state sensor that can receive data indicating whether an AHU fan might be running and use that data to determine whether to draw in fresh air. In some examples, the data can include a signal from a current-sensing switch that can send a signal when current is detected from power being supplied to the AHU. In some examples, the data can include a signal from a pressure sensor that detects a change in static pressure, such as in an duct of the HVAC system.

1 . An HVAC system comprising:
 an air-handling-unit (AHU) fan configured to propel air to a conditioned-air space;   a motor coupled to the AHU fan;   a first controller that exchanges communications via a first communications protocol and that is configured to control operations of the AHU fan, the motor, or both the AHU fan and the motor;   a fresh-air-ventilation (FAV) equipment configured to draw fresh air from outside of the conditioned-air space;   a second controller that exchanges communications via a second communications protocol, which is different from the first communications protocol, and that is configured to control operations of the FAV equipment; and   an AHU-state sensor that is coupled to the second controller and that is configured to, without using the first communications protocol, determine at least one of whether the AHU fan is propelling the air or whether power is being supplied to the motor.   
     
     
         2 . The HVAC system of  claim 1 , wherein the first communications protocol is a proprietary communications protocol. 
     
     
         3 . The HVAC system of  claim 2 , wherein the AHU fan is a component of a variable refrigerant flow (VRF) system. 
     
     
         4 . The HVAC system of  claim 1 , wherein the AHU-state sensor comprises a current-sensing switch that is configured to detect a change in an electrical current supplying power to the AHU fan or the motor. 
     
     
         5 . The HVAC system of  claim 1 , wherein the AHU-state sensor comprises a pressure switch configured to detect a change in a static pressure associated with a duct fluidly coupled with the AHU fan. 
     
     
         6 . The HVAC system of  claim 1  further comprising, a second sensor configured to detect at least one of a humidity or a temperature of the fresh air. 
     
     
         7 . The HVAC system of  claim 1  further comprising, a discharge air temperature (DAT) sensor configured to detect a temperature of the air provided to the conditioned-air space. 
     
     
         8 . The HVAC system of  claim 1 , wherein the FAV equipment comprises a FAV fan. 
     
     
         9 . The HVAC system of  claim 1 , wherein the FAV equipment comprises a damper. 
     
     
         10 . A ventilation system for an HVAC system, the ventilation system comprising:
 fresh-air-ventilation (FAV) equipment comprising at least one of a FAV fan or a FAV damper, wherein the FAV equipment is configured to draw fresh air into a mixed plenum of the HVAC system;   a controller that is configured to control operations of the FAV equipment;   one or more fresh-air quality sensors that are coupled to the controller and that are configured to measure at least one of a temperature or a humidity of the fresh air; and   an air-handling-unit (AHU) state sensor that is coupled to the controller and that is configured to determine at least one of whether an AHU fan is propelling air or whether power is being supplied to a motor coupled to the AHU fan, wherein the controller increases an amount of fresh air drawn into the mixed plenum in response to the AHU state sensor determining that the AHU fan is propelling air or that the power is being supplied to the motor.   
     
     
         11 . The ventilation system of  claim 10 , wherein the AHU state sensor comprises a current-sensing switch configured to detect a change in an electrical current supplying power to the motor. 
     
     
         12 . The ventilation system of  claim 10 , wherein the AHU state sensor comprises a pressure switch configured to detect a change in a static pressure associated with a duct of the HVAC system. 
     
     
         13 . The ventilation system of  claim 10 , wherein the controller is electronically coupled to a discharge air temperature (DAT) sensor configured to detect a temperature of the air propelled by the AHU fan. 
     
     
         14 . The ventilation system of  claim 10 , wherein the controller comprises a printed circuit board comprising respective connections to the FAV equipment, the one or more fresh-air quality sensors, and the AHU state sensor. 
     
     
         15 . A ventilation controller for an HVAC system, the ventilation controller comprising:
 a printed circuit board comprising:
 connectors that are electronically coupled to fresh-air-ventilation (FAV) equipment, a discharge-air-temperature (DAT) sensor that measures at least one of temperature and humidity of conditioned air, and an air-handling-unit (AHU) state sensor; and 
 one or more fresh-air quality sensors that measure at least one of temperature and humidity of unconditioned air. 
   
     
     
         16 . The ventilation controller of  claim 15 , wherein the AHU state sensor comprises a current-sensing switch configured to detect a change in an electrical current. 
     
     
         17 . The ventilation controller of  claim 15 , wherein the AHU state sensor comprises a pressure switch configured to detect a change in a static pressure associated with a duct of the HVAC system.