Variable air volume system including BTU control function

• US 20060091227A1
• Filed: 04/11/2005
• Published: 05/04/2006
• Est. Priority Date: 10/17/2003
• Status: Active Grant

• Current Assignee: Siemens Industry Incorporated (Siemens AG)
• Original Assignee: Siemens Industry Incorporated (Siemens AG)
• Inventors: Attridge, Russell G. Jr.
• Granted Patent: US 7,551,983 B2
• Time in Patent Office: Days
• US Class Current: 236/1.00B
• 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 11/46 Improving electric energy efficiency or saving
• CPC Class Codes: F24F 11/63 Electronic processing
• CPC Class Codes: F24F 11/74 for controlling air flow rate or air velocity
• CPC Class Codes: F24F 3/0442 with volume control at a constant temperature

Abstract

A method, as well as a controller, for controlling room temperature within a variable air volume system having a plurality of zones wherein the thermal transfer rate with respect to each of such zones is maintained at a substantially constant value notwithstanding changes in the temperature of the supply air thereby providing improved efficiency and environmental comfort.

Claims

1. A method of improving environmental comfort in a variable air volume system having a plurality of zones, said system including a flow control box associated with each of said zones for individually regulating flow volume of supply air into each of said zones to maintain room temperature of said individual zones at or near preselected set point temperatures, said supply air being provided at a preselected temperature T, comprising the steps of:

determining said flow volume of said supply air flowing through said boxes; and

adjusting said supply air temperature to increase said flow volume through said boxes when at least one of said boxes is operating in a restricted flow mode whereby environmental comfort is improved.

2. The method according to claim 2, wherein said determining step directly measures said flow volume through said boxes.

3. The method according to claim 2, wherein said determining step calculates whether a first preselected number of boxes are operating in said restricted flow mode.

4. The method according to claim 3, wherein said adjusting step increases/decreases said supply air temperature until a second preselected number of boxes are operating in an unrestricted flow mode.

5. The method according to claim 4, wherein the room temperature in said zones associated with said second preselected number of boxes is less than or equal to ±

2°

F. with respect to said preselected set point temperatures.

6. The method according to claim 5, wherein the room temperature in said zones associated with said second preselected number of boxes is less than or equal to ±

1.0°

F. with respect to said preselcted set point temperatures.

7. The method according to claim 5, wherein said restricted flow mode is less than or equal to 50% of a predetermined maximum flow volume.

8. The method according to claim 37, wherein said restricted flow mode is less than or equal to 33% of a predetermined maximum flow volume.

9. The method according to claim 38, wherein said adjusting step increases the temperature of said supply air when said system is in a cooling mode and decreases the temperature of said supply air when said system is in a heating mode.

10. The method according to claim 39, including the further step of calculating an adjusted supply air temperature, and wherein said adjusting step includes the step of signaling said system to automatically reset said supply air temperature to said adjusted supply air temperature.

11. A method of controlling a variable air volume system having a plurality of zones, said system including a flow control box associated with each of said zones for regulating flow volume of supply air into each of said zones, said supply air being provided at a temperature T, comprising:

providing an output signal at each of said flow control boxes corresponding to a predetermined proportional band, a first portion of said proportional band corresponding to control of said flow control box and a second portion of said proportional band providing an indication of unmet thermal load in said respective zone;

monitoring said boxes to identify select boxes wherein said output signal corresponds to said second portion of said proportional band; and

providing a reset signal for adjustment of said supply air temperature in accordance with predefined system criteria when said output signal from said select boxes corresponds to said second portion of said proportional band.

12. The method according to claim 41, further comprising the step of establishing a set point reference between said first and second portions of said proportional band, said set point reference corresponding to a preselected set point temperature for said respective zone.

13. The method according to claim 42, further comprising the steps of:

assigning a first negative temperature deviation to a first end of said proportional band and a second positive temperature deviation to a second end of said proportional band, and

assigning said set point reference to correspond to a temperature deviation of zero.

14. The method according to claim 43, wherein said temperature deviation is calculated according to the formula:

Temperature Deviation=Room Temperature−

Set Point Temperature

and further comprising the steps of

calculating said temperature deviation;

determining said corresponding output signal from said proportional band;

adjusting said flow control box in accordance with said corresponding output signal.

15. The method according to claim 44, further comprising the step of:

signaling said flow control box to provide maximum flow volume into said zone when said temperature deviation is at or above set point.