Method for controlling an economizer

• US 6,634,422 B2
• Filed: 03/19/2001
• Issued: 10/21/2003
• Est. Priority Date: 06/22/1999
• Status: Expired due to Fees

• Current Assignee: Aventis Research & Technologies GmbH & Co. KG (Bristol-Myers Squibb Company)
• Original Assignee: York International Corporation (Johnson Controls International plc)
• Inventors: Rayburn, Ronald Richard, Pickle, Stephen Blake, Wilson, Stephen Carl
• Primary Examiner(s): CIRIC, LJILJANA V
• Application Number:
  US09/810,555
• Publication Number:
  US 20030042015A1
• Time in Patent Office: 946 Days
• Field of Search: 165/209, 165/217, 165/248, 165/249, 165/250, 165/251, 236/49.3, 454/256
• US Class Current: 165/250
• CPC Class Codes: F24F 11/70 Control systems characterised by their outputs; Constructional details thereof
• CPC Class Codes: F24F 11/76 by means responsive to temperature, e.g. bimetal springs
• CPC Class Codes: F24F 2011/0002 for admittance of outside air

Abstract

A method of controlling an economizer is provided. A heating, ventilating, and air conditioning unit is operated in one of a heating mode and a cooling mode to provide conditioned air to a plurality of zones. A first temperature representative of air returned to the unit from the plurality of zones is sensed and a second temperature representative of the outdoor air is sensed. An economizer is modulated to increase the amount of outdoor air entering the unit when the first temperature falls below a cooling setpoint, the second temperature is greater than the first temperature, and the unit is operating in the cooling mode. The economizer is also modulated to increase the amount of outdoor air entering the unit when the first temperature rises above a heating setpoint, the second temperature is lower than the first temperature, and the unit is operating in the heating mode.

Claims

1. A method of controlling an economizer, comprising the steps of:

operating a heating, ventilating, and air conditioning unit in one of a heating mode and a cooling mode to provide conditioned air to a plurality of zones, said unit having an economizer operable to allow variable amounts of outdoor air into said unit;

sensing a first temperature representative of air returned to said unit from the plurality of zones;

sensing a second temperature representative of the outdoor air;

modulating the economizer to increase the amount of outdoor air entering said unit when the first temperature falls below a cooling setpoint, the second temperature is greater than the first temperature, and said unit is operating in the cooling mode; and

modulating the economizer to increase the amount of outdoor air entering said unit when the first temperature rises above a heating setpoint, the second temperature is lower than the first temperature, and said unit is operating in the heating mode.

2. The method of claim 1, further comprising the step of programming the cooling setpoint and the heating setpoint into a control device associated with said unit.

3. The method of claim 1, wherein the cooling setpoint is approximately 50°

F.

4. The method of claim 1, wherein the economizer is modulated to increase the amount of outdoor air entering said unit when said unit is operating in the cooling mode, the first temperature is below the cooling setpoint, and the second temperature is greater than a first preset limit.

5. The method of claim 4, wherein the first preset limit is between about 60°

F. and 80°

F.

6. The method of claim 5, further comprising the step of programming the first preset limit into a control device associated with said unit.

7. The method of claim 1, further comprising the step of modulating the economizer to reduce the amount of outdoor air entering said unit when said unit is operating in the cooling mode and the first temperature rises more than about 5°

F. above the cooling setpoint.

8. The method of claim 1, wherein the heating setpoint is within the range of approximately 110°

F. and 160°

F.

9. The method of claim 1, wherein the economizer is modulated to increase the amount of outdoor air entering said unit when said unit is operating in the heating mode, the first temperature is above the heating setpoint, and the second temperature is less than a second preset limit.

10. The method of claim 9, wherein the second preset limit is about 50°

F. less than the heating setpoint.

11. The method of claim 10, further comprising the step of programming the second preset limit into a control device associated with said unit.

12. The method of claim 1, further comprising the step of modulating the economizer to reduce the amount of outdoor air entering said unit when said unit is operating in the heating mode and the first temperature drops more than about 10°

F. below the heating setpoint.

19. The method of claim 1, further comprising the step of modulating the economizer to reduce the amount of outdoor air entering said unit when the first temperature rises more than about 5°

F. above the cooling setpoint.

13. A method of controlling an economizer, comprising the steps of:

operating a conditioning unit in a heating mode to provide conditioned air to a plurality of zones, said unit having an economizer operable to allow variable amounts of outdoor air into said unit;

sensing a first temperature representative of air returned to said unit from the plurality of zones;

sensing a second temperature representative of the outdoor air; and

modulating the economizer to increase the amount of outdoor air entering said unit when the first temperature rises above a heating setpoint, the second temperature is lower than the first temperature, and said unit is operating in the heating mode.

14. The method of claim 13, further comprising the step of programming the cooling setpoint into a control device associated with said unit.

15. The method of claim 13, wherein the cooling setpoint is approximately 50°

F.

16. The method of claim 13, wherein the economizer is modulated to increase the amount of outdoor air entering said unit when the first temperature is below the cooling setpoint, and the second temperature is greater than a first preset limit.

17. The method of claim 16, wherein the first preset limit is between about 60°

F. and 80°

F.

18. The method of claim 17, further comprising the step of programming the first preset limit into a control device associated with said unit.

20. A method of controlling an economizer, comprising the steps of:

operating a conditioning unit in a cooling mode to provide conditioned air to a plurality of zones, said unit having an economizer operable to allow variable amounts of outdoor air into said unit;

sensing a first temperature representative of air returned to said unit from the plurality of zones;

sensing a second temperature representative of the outdoor air; and

modulating the economizer to increase the amount of outdoor air entering said unit when the first temperature falls below a cooling setpoint, the second temperature is greater than the first temperature, and said unit is operating in the cooling mode.

21. The method of claim 20, further comprising the step of programming the heating setpoint into a control device associated with said unit.

22. The method of claim 21, wherein the heating setpoint is within the range of approximately 110°

F. and 160°

F.

23. The method of claim 22, further comprising the step of programming the second preset limit into a control device associated with said unit.

24. The method of claim 20, wherein the economizer is modulated to increase the amount of outdoor air entering said unit when said unit is operating in the heating mode, the first temperature is above the heating setpoint, and the second temperature is less than a second preset limit.

25. The method of claim 24, wherein the second preset limit is about 50°

F. less than the heating setpoint.

26. The method of claim 20, further comprising the step of modulating the economizer to reduce the amount of outdoor air entering said unit when said unit is operating in the heating mode and the first temperature drops more than about 10°

F. below the heating setpoint.