MULTI-STAGE CONTROL FOR ELECTROMECHANICAL HEATING, VENTILATION, AND AIR CONDITIONING (HVAC) UNIT

• US 20170030623A1
• Filed: 08/01/2016
• Published: 02/02/2017
• Est. Priority Date: 07/31/2015
• Status: Active Grant

• Current Assignee: Trane International Inc. (Trane Technologies plc)
• Original Assignee: Trane International Inc. (Trane Technologies plc)
• Inventors: Smith, Sean A.
• Granted Patent: US 10,551,105 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: F24F 11/86 by controlling compressors within refrigeration or heat pump circuits
• CPC Class Codes: F25B 2400/0751 the compressors having different capacities
• CPC Class Codes: F25B 2600/01 Timing
• CPC Class Codes: F25B 2600/02 Compressor control
• CPC Class Codes: F25B 2600/025 by controlling speed
• CPC Class Codes: F25B 2700/19 Pressures
• CPC Class Codes: F25B 2700/2104 of an indoor room or compartment
• CPC Class Codes: F25B 2700/2106 of fresh outdoor air
• CPC Class Codes: F25B 49/022 Compressor control arrangements

Abstract

A control system for a heat transfer circuit, an HVAC unit containing a heat transfer circuit, and a method of retrofitting an HVAC unit are described. The control system includes a thermostat having a first cooling stage signal output terminal and a second cooling stage signal output terminal; a controller electrically connected to the thermostat; a sensor electrically connected to the controller; and a switch electrically connected to the controller, and that receives a first cooling stage signal output from the thermostat. The switch is in a first state when a sensor value from the sensor is less than a threshold, and a second state when the sensor value from the sensor is greater than or equal to the threshold.

Claims

1. A control system for a heat transfer circuit, comprising:

a thermostat having a first cooling level signal output terminal and a second cooling level signal output terminal;

a controller electrically connected to the thermostat;

a sensor electrically connected to the controller; and

a switch electrically connected to the controller, and that receives a first cooling level signal output from the thermostat, wherein the switch is in a first state when a sensor value from the sensor is less than a threshold, and a second state when the sensor value from the sensor is greater than or equal to the threshold, and

wherein the first cooling level signal output enables a first cooling stage or a second cooling stage and a second cooling level signal output enables a third cooling stage.

2. The control system according to claim 1, wherein the switch is electrically connected to a first compressor and a second compressor, such that when the switch is in the first state, the first compressor receives the first cooling level signal output from the thermostat.

3. The control system according to claim 2, wherein when the switch is in the second state, the second compressor receives the first cooling level signal output from the thermostat.

4. The control system according to claim 2, wherein the first and second compressors receive the second cooling level signal output from the thermostat.

5. The control system according to claim 1, wherein the sensor is one of a temperature sensor, a pressure sensor, a timer, and a humidity sensor.

6. The control system according to claim 5, wherein the sensor and the switch are combined.

7. The control system according to claim 6, wherein the combined sensor and switch are a bimetallic thermal switch.

8. A heat transfer circuit, comprising:

a plurality of compressors, each of the plurality of compressors having different capacities; and

a control system, comprising;

a thermostat having a first cooling level signal output terminal and a second cooling level signal output terminal;

a controller electrically connected to the thermostat;

a sensor electrically connected to the controller; and

a switch electrically connected to the controller, and that receives a first cooling level signal output from the thermostat,

wherein the switch is in a first state when a sensor value from the sensor is less than a threshold, and a second state when the sensor value from the sensor is greater than or equal to the threshold, and

wherein the first cooling level signal output enables a first cooling stage or a second cooling stage and a second cooling level signal output enables a third cooling stage.

9. The heat transfer circuit according to claim 8, wherein the first cooling level signal output enables one of the plurality of compressors based on a state of the switch.

10. The heat transfer circuit according to claim 9, wherein a first of the plurality of compressors is enabled when the switch is in the first state.

11. The heat transfer circuit according to claim 9, wherein a second of the plurality of compressors is enabled when the switch is in the second state.

12. The heat transfer circuit according to claim 8, wherein all of the plurality of compressors are enabled in response to the second cooling level signal output from the thermostat.

13. The heat transfer circuit according to claim 8, wherein the sensor is one of a temperature sensor, a pressure sensor, a timer, and a humidity sensor.

14. The control system according to claim 13, wherein the sensor and the switch are combined.

15. The control system according to claim 14, wherein the combined sensor and switch are a bimetallic thermal switch.

16. A method of retrofitting a heating, ventilation, and air conditioning (HVAC) unit, the HVAC unit including a thermostat and a plurality of compressors, the thermostat including a first cooling level output terminal and a second cooling level output terminal, the method comprising:

connecting a switch in electrical communication with the thermostat and the plurality of compressors, such that the switch is electrically connected to the first cooling level output terminal; and

connecting a sensor in electrical communication with the thermostat and the switch, wherein the sensor is configured to selectively modify a state of the switch based on a sensor value, such that the switch controls whether a first of the plurality of compressors is enabled or a second of the plurality of compressors is enabled; and

connecting the plurality of compressors to the second cooling level output terminal such that all of the plurality of compressors are enabled when a second cooling level output signal is output from the second cooling level output terminal.

17. The method according to claim 16, wherein the switch and the sensor are combined.

18. The method according to claim 16, wherein the combined switch and sensor is a bimetallic thermal switch.