Hvac control system for electric heating system

Abstract

A heating, ventilation, and air conditioning (HVAC) system includes a housing defining a chamber configured to receive an air flow and a heating system disposed within the housing. The heating system includes a heating coil disposed within the chamber and configured to transfer heat to the air flow within the chamber and a power supply control system configured to control supply of an electric current to the heating coil. The power supply control system includes power supply control circuitry disposed at least partially external to the chamber and a switch disposed along the power supply control circuitry. The switch is configured to open to interrupt supply of the electric current to the heating coil and to close to enable supply of the electric current to the heating coil based on an operating parameter indicative of the air flow within the chamber.

1 . A heating, ventilation, and air conditioning (HVAC) system, comprising:
 a housing defining a chamber configured to receive an air flow; and   a heating system disposed within the housing, wherein the heating system comprises:
 a heating coil disposed within the chamber and configured to transfer heat to the air flow within the chamber; and 
 a power supply control system configured to control supply of an electric current to the heating coil, wherein the power supply control system comprises power supply control circuitry disposed at least partially external to the chamber and a switch disposed along the power supply control circuitry, wherein the switch is configured to open to interrupt supply of the electric current to the heating coil and to close to enable supply of the electric current to the heating coil based on an operating parameter indicative of the air flow within the chamber. 
   
     
     
         2 . The HVAC system of  claim 1 , wherein the housing comprises a power component section, and the power supply control circuitry and the switch are disposed within the power component section. 
     
     
         3 . The HVAC system of  claim 2 , wherein the housing comprises a partition extending between and separating the chamber and the power component section. 
     
     
         4 . The HVAC system of  claim 3 , wherein the switch comprises an air proving switch. 
     
     
         5 . The HVAC system of  claim 4 , wherein the air proving switch comprises a first port fluidly coupled to the chamber and a second port fluidly coupled to the power component section. 
     
     
         6 . The HVAC system of  claim 5 , comprising:
 a conduit connector coupled to and extending through the partition; and   a conduit extending from the conduit connector to the first port of the air proving switch,   wherein the second port is fluidly coupled to the chamber via the conduit connector and the conduit.   
     
     
         7 . The HVAC system of  claim 2 , wherein the operating parameter comprises a pressure differential between the chamber and the power component section. 
     
     
         8 . The HVAC system of  claim 7 , wherein the switch is configured to close in response to detection of the pressure differential being greater than a threshold value. 
     
     
         9 . The HVAC system of  claim 7 , wherein the switch is configured to open in response to detection of the pressure differential being less than a threshold value. 
     
     
         10 . The HVAC system of  claim 1 , wherein the power supply control system comprises:
 an electrical contactor configured to transmit the electric current from a power source to the heating coil; and   a heating system relay comprising a set of relay contacts, wherein the set of relay contacts is configured to transmit a signal indicative of a call for heating from a control system of the HVAC system to the electrical contactor in a closed configuration of the set of relay contacts.   
     
     
         11 . The HVAC system of  claim 10 , wherein the set of relay contacts comprises a normally open configuration. 
     
     
         12 . The HVAC system of  claim 11 , wherein the heating system relay comprises a coil, the switch is configured to transmit a voltage to the coil in a closed configuration of the switch, the coil is configured to transition the set of relay contacts to the closed configuration in response to receipt of the voltage. 
     
     
         13 . The HVAC system of  claim 12 , wherein the power supply control circuitry comprises at least one limit switch, the at least one limit switch is configured to open in response to detection of temperature of air within the chamber above a threshold temperature, the at least one limit switch, the switch, and the heating system relay are arranged in series along the power supply control circuitry, and the switch is disposed between the at least one limit switch and the heating system relay relative to a direction of the voltage along the power supply control circuitry. 
     
     
         14 . A heating system for a heating, ventilation, and air conditioning (HVAC) system, comprising:
 an electric heating coil configured to transfer heat to an air flow directed through the HVAC system; and   a power supply control system configured to control supply of a first voltage to the electric heating coil, wherein the power supply control system comprises:
 an electrical contactor configured to transmit the first voltage from a power source to the electric heating coil; 
 a relay comprising a coil and a set of relay contacts, wherein the set of relay contacts is configured to transmit a signal indicative of a call for heating from a control system of the HVAC system to the electrical contactor in a closed configuration of the set of relay contacts, and the coil is configured to transition the set of relay contacts from a normally open configuration to the closed configuration in response to receipt of a second voltage; and 
 a switch configured to transmit the second voltage to the coil of the relay in a closed configuration of the switch and configured to interrupt transmission of the second voltage to the coil of the relay in an open configuration of the switch, wherein the switch is configured to transition between the open configuration and the closed configuration based on a detected parameter indicative of the air flow directed through the HVAC system. 
   
     
     
         15 . The heating system of  claim 14 , wherein the electric heating coil is configured to be disposed within a supply air section of the HVAC system, the power supply control system is configured to be disposed within a power component section of the HVAC system, the heating system comprises a partition configured to extend between the supply air section and the power component section. 
     
     
         16 . The heating system of  claim 15 , wherein the switch is a pressure switch comprising a first port configured to fluidly couple to the supply air section and a second port configured to fluidly couple to the power component section, and the detected parameter comprises a pressure differential between the supply air section and the power component section. 
     
     
         17 . The heating system of  claim 16 , wherein the relay, the switch, or both are configured to be mounted to the partition within the power component section. 
     
     
         18 . The heating system of  claim 16 , wherein the pressure switch is configured to transition from the open configuration to the closed configuration in response to detection of the pressure differential being greater than a threshold value. 
     
     
         19 . The heating system of  claim 14 , wherein the power supply control system comprises a circuit configured to transmit the second voltage, the circuit is configured to receive the second voltage from a control board of the HVAC system, and the relay and the switch are arranged in series along the circuit. 
     
     
         20 . A heating, ventilation, and air conditioning (HVAC) system, comprising:
 a housing defining a blower section, a supply air section, and a power component section;   a blower disposed within the blower section and configured to direct an air flow into the supply air section;   an electric heating coil disposed within the supply air section and configured to transfer heat to the air flow;   a partition disposed within the housing and extending between the supply air section and the power component section; and   a power supply control system configured to control supply of a first voltage to the electric heating coil, wherein the power supply control system comprises:
 an electrical contactor configured to transmit the first voltage from a power source to the electric heating coil in response to receipt of a call for heating from a control system of the HVAC system; 
 a relay configured to electrically couple the control system of the HVAC system and the electrical contactor in response to receipt of a second voltage; and 
 an air proving switch configured to transition from an open configuration to a closed configuration to enable transmission of the second voltage to the relay in response to detection of a pressure differential between the supply air section and the power component section greater than a threshold value.