AUTOMATIC CHANGEOVER CONTROL FOR AN HVAC SYSTEM

• US 20120061068A1
• Filed: 09/13/2010
• Published: 03/15/2012
• Est. Priority Date: 09/13/2010
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Yang, Gary, Wacker, Paul, Anderson, Amy L., Zhang, Camel, Zhao, Angela, Dalsin, Nicholas
• Granted Patent: US 9,157,646 B2
• Time in Patent Office: Days
• US Class Current: 165/254
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/52 Indication arrangements, e.g. displays
• CPC Class Codes: F24F 11/56 Remote control
• CPC Class Codes: F24F 11/65 for selecting an operating mode
• CPC Class Codes: F24F 11/67 Switching between heating and cooling modes
• CPC Class Codes: F24F 11/74 for controlling air flow rate or air velocity
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: F24F 2221/54 Heating and cooling, simultaneously or alternatively

Abstract

The present disclosure describes methods and apparatus for automatically changing between heating and cooling modes of an HVAC system, sometimes using a single or common set point in both modes. In an illustrative but not limiting example, an HVAC controller may monitor the temperature of an inside space of a building, and may switch the HVAC system to a cooling mode when the temperature of the inside space rises above a high switch-point temperature, and may cool the inside space to at least below the high switch-point temperature. The HVAC controller may also switch the HVAC system to the heating mode when the temperature of the inside space falls below a low switch-point temperature and may heat the inside space to at least above the low switch-point temperature. In some cases, after switching to the heating mode, the HVAC controller may cause the HVAC system to heat the inside space to substantially the set-point temperature. Likewise, after switching to the cooling mode, the HVAC controller may cause the HVAC system to cool the inside space to substantially the set-point temperature.

Claims

1. A method of operating an HVAC system that is capable of controlling the temperature of an inside space of a building, the HVAC system having both a heating mode and a cooling mode, the method comprising:

monitoring a temperature of the inside space of the building;

identifying a set-point temperature;

identifying a low switch-point temperature and a high switch-point temperature, wherein the low switch-point temperature is below the set-point temperature and the high switch-point temperature is above the set-point temperature;

causing the HVAC system to switch to the heating mode when the temperature of the inside space falls below the low switch-point temperature, and to heat the inside space to at least above the low switch-point temperature; and

causing the HVAC system to switch to the cooling mode when the temperature of the inside space rises above the high switch-point temperature, and to cool the inside space to at least below the high switch-point temperature.

2. The method of claim 1, wherein:

after the HVAC system switches to the heating mode, the HVAC system heats the inside space to substantially the set-point temperature; and

after the HVAC system switches to the cooling mode, the HVAC system cools the inside space to substantially the set-point temperature.

3. The method of claim 2, wherein:

after the HVAC system heats the inside space to substantially the set-point temperature, cycling the HVAC system on and off in the heating mode to maintain the temperature of the inside space at substantially the set-point temperature; and

after the HVAC system cools the inside space to substantially the set-point temperature, cycling the HVAC system on and off in the cooling mode to maintain the temperature of the inside space at substantially the set-point temperature.

4. The method of claim 1, wherein:

after the HVAC system heats the inside space to at least above the low switch-point temperature, cycling the HVAC system on and off in the heating mode to maintain the temperature of the inside space within a predefined temperature range, wherein the predefined temperature range is less than the difference between the high and the low switch-point temperatures; and

after the HVAC system cools the inside space to at least below the high switch-point temperature, cycling the HVAC system on and off in the cooling mode to maintain the temperature of the inside space within a predefined temperature range, wherein the predefined temperature range is less than the difference between the high and the low switch-point temperatures.

5. The method of claim 1 further comprising providing a set-back mode, wherein when the HVAC system is switched to the set-back mode, the set-point temperature, the high switch-point temperature, and the low switch-point temperature all change to different pre-determined set-back values.

6. A method of operating an HVAC system that is capable of controlling the temperature in an inside space of a building, the HVAC system having both a heating mode and a cooling mode, the method comprising:

monitoring a temperature of the inside space of the building;

identifying at least one set-point temperature;

identifying a low switch-point temperature and a high switch-point temperature, wherein the low switch-point temperature is less than the set-point temperature and the high switch-point temperature is greater than the set-point temperature;

causing the HVAC system to switch to the heating mode when the temperature of the inside space falls below the low switch-point temperature, and to heat the inside space to at least above the low switch-point temperature, and after the HVAC system heats the inside space to at least above the low switch-point temperature, causing the HVAC system to selectively switch on and off in the heating mode to maintain the temperature of the inside space above the low switch-point temperature; and

causing the HVAC system to switch to the cooling mode when the temperature of the inside space rises above the high switch-point temperature, and to cool the inside space to at least below the high switch-point temperature, and after the HVAC system cools the inside space to at least below the high switch-point temperature, causing the HVAC system to selectively switch on and off in the cooling mode to maintain the temperature of the inside space below the high switch-point temperature.

7. The method of claim 6, wherein the HVAC system, after switching to the heating mode, heats the inside space to substantially the set-point temperature.

8. The method of claim 7, wherein the HVAC system is selectively switched on and off in the heating mode to maintain the temperature of the inside space within a predefined temperature range, wherein the predefined temperature range is less than the difference between the high and the low switch-point temperatures.

9. The method of claim 6, wherein the HVAC system, after switching to the cooling mode, cools the inside space to substantially the set-point temperature.

10. The method of claim 9, wherein the HVAC system is selectively switched on and off in the cooling mode to maintain the temperature of the inside space within a predefined temperature range, wherein the predefined temperature range is less than the difference between the switch-point temperatures.

11. The method of claim 6 further comprising providing a set-back mode, wherein when the HVAC system switches to the set-back mode, the set-point temperature, the high switch-point temperature, and the low switch-point temperature all change to different pre-determined set-back values.

12. An HVAC controller for controlling an HVAC system of a building, the HVAC system having at least a heating mode and a cooling mode, the HVAC controller comprising:

a control module programmed to;

monitor a temperature of an inside space of the building;

identify at least one set-point temperature;

identify a low switch-point temperature and a high switch-point temperature, wherein the low switch-point temperature is below the set-point temperature and the high switch-point temperature is above the set-point temperature;

switch the HVAC system to the cooling mode when the temperature of the inside space rises above the high switch-point temperature, and to cool the inside space to at least below the high switch-point temperature; and

switch the HVAC system to the heating mode when the temperature of the inside space falls below the low switch-point temperature, and to heat the inside space to at least above the low switch-point temperature.

13. The HVAC controller of claim 12, wherein after switching to the heating mode, the HVAC controller causes the HVAC system to heat the inside space to substantially the set-point temperature.

14. The HVAC controller of claim 13, wherein after the HVAC controller causes the HVAC system to heat the inside space to substantially the set-point temperature, the HVAC controller selectively switches the HVAC system on and off in the heating mode to maintain the temperature of the inside space within a predefined temperature range, wherein the predefined temperature range is less than the difference between the high and the low switch-point temperatures.

15. The HVAC controller of claim 12, wherein after switching to the cooling mode, the HVAC controller causes the HVAC system to cool the inside space to substantially the set-point temperature.

16. The HVAC controller of claim 15, wherein after the HVAC controller causes the HVAC system to cool the inside space to substantially the set-point temperature, the HVAC controller selectively switches the HVAC system on and off in the cooling mode to maintain the temperature of the inside space within a predefined temperature range, wherein the predefined temperature range is less than the difference between the high and the low switch-point temperatures.

17. The HVAC controller of claim 12, where the HVAC controller further includes a memory for storing at least one of the set-point temperature, the high switch-point temperature and the low switch-point temperature are stored in the memory of the HVAC controller.

18. The HVAC controller of claim 17, where the memory further stores at least one set-back set-point temperature.

19. The HVAC controller of claim 12, where the HVAC controller is a wall-mountable thermostat that includes an internal temperature sensor.

20. The HVAC controller of claim 12, wherein the HVAC system is a fan coil system.