Energy reducing retrofit method and apparatus for a constant volume HVAC system

• US 8,965,586 B2
• Filed: 06/18/2013
• Issued: 02/24/2015
• Est. Priority Date: 08/20/2009
• Status: Active Grant

• Current Assignee: Pro Star Energy Solutions LLC
• Original Assignee: Transformative Wave Technologies LLC (Performance Mechanical Group)
• Inventors: Miller, Danny, Sipe, Justin
• Primary Examiner(s): Fennema, Robert
• Assistant Examiner(s): Norton, Jennifer L
• Application Number:
  US13/920,331
• Publication Number:
  US 20130282183A1
• Time in Patent Office: 616 Days
• Field of Search: 700/276, 621/86, 165/201, 236/49.3, 236/44.C, 236/44.R, 454/333, 454/239, 454/256
• US Class Current: 700/276
• 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 11/58 using Internet communication
• CPC Class Codes: F24F 11/62 characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
• CPC Class Codes: F24F 11/77 by controlling the speed of ventilators
• CPC Class Codes: F24F 2011/0006 using low temperature external supply air to assist cooling
• CPC Class Codes: F24F 2110/20 Humidity
• CPC Class Codes: F24F 2110/50 Air quality properties
• CPC Class Codes: F24F 2110/70 Carbon dioxide
• CPC Class Codes: G05B 19/042 using digital processors G05B19/05 takes precedence
• CPC Class Codes: G05B 19/05 Programmable logic controllers, e.g. simulating logic interconnections of signals according to ladder diagrams or function charts
• CPC Class Codes: G05B 2219/1133 Sensor actuator, asi, bus, network
• CPC Class Codes: G05B 2219/25289 Energy saving, brown out, standby, sleep, powerdown modus for microcomputer
• CPC Class Codes: G05B 2219/2614 HVAC, heating, ventillation, climate control
• CPC Class Codes: G05D 23/1919 characterised by the type of controller
• CPC Class Codes: G05D 7/0676 by action on flow sources G05D7/0688, G05D7/0694 take precedence
• CPC Class Codes: H04L 67/12 specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
• CPC Class Codes: H04L 67/125 involving control of end-device applications over a network
• CPC Class Codes: Y02B 30/54 Free-cooling systems
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
• CPC Class Codes: Y02B 30/90 : Passive houses; Double facade technology

Abstract

An energy-reducing method and apparatus for retrofitting a constant volume HVAC system, with or without an economizer, that provides heating, cooling, and ventilation to occupants within a building space. The present invention includes the introduction of a programmable logic controller and variable frequency drive (VFD) that takes control of the existing fan, heating, cooling, and optional economizer operation. The controller is programmed fault detection of fan fault, heat/cool (temperature-based) fault, and energy consumption fault. The reduction of the fan speed in the ventilation mode when the 100% operation is not needed saves significant energy of the existing constant volume HVAC system where the fan motor is designed to run 100% of the time.

Claims

1. A method of reducing energy consumption by retrofitting a preexisting single zone constant volume HVAC system that provides one or more of the following:

heating, cooling, or ventilation to an indoor space within a single zone of a building that has periodic occupancy, wherein the heating, cooling, or ventilation is initiated based upon preset conditions or on occupancy command and wherein the preexisting HVAC system includes a fan assembly configured to operate between no operation and a maximum ventilation with a range of operation from 0 to 100%, a thermostatic device, heating and/or cooling equipment having preexisting equipment control terminations, the energy reducing method comprising;

providing a programmable logic controller that can receive input from the thermostatic device and send heating, cooling, and ventilation instructions to a preexisting fan assembly for ventilating an indoor space within a single zone of a building, and to a preexisting heating assembly that can send heat to the same indoor space, and to a preexisting cooling assembly that can send cooling to the same indoor space; and

operably connecting the programmable logic controller to preexisting equipment control terminations;

providing a variable frequency drive (VFD), controlled by the programmable logic controller, and operably connecting the VFD to the preexisting fan assembly;

operating the preexisting HVAC system in a ventilation mode, a heating mode, and/or a cooling mode, controlled by the programmable logic controller;

operating the preexisting fan assembly at a reduced speed during the ventilation mode when the less than maximum ventilation is required; and

providing fault detection via a discharge air sensor or current status switch.

2. The method according to claim 1 wherein the fault detection further comprises interconnecting a fan fault and a heat/cool (temperature-based) fault.

3. The method according to claim 2 further comprising running the fan fault detection first and then running the heat/cool (temperature-based) fault detection;

wherein an energy consumption fault is added and is independent of the fan fault and the heat/cool (temperature-based) fault detection.

4. The method according to claim 1 wherein the fan assembly is run at a reduced speed during the heating and/or cooling mode.

5. The method according to claim 1 wherein the fan speed is reduced in the range of 10% to 90% in the ventilation mode.

6. The method according to claim 4 wherein the fan speed is reduced in the range of 1%-30% in the heating and/or cooling mode.

7. The method according to claim 1 further comprising providing an occupancy indicator to determine occupancy levels within the building space and sending the indicated occupancy level to the controller.

8. The method according to claim 7 wherein the fan speed is reduced in the range of 10% to 90% in the ventilation mode in response to the indicated occupancy needs.

9. The method according to claim 1 wherein the programmable logic controller and VFD are incorporated into a single unit.

10. The method according to claim 1 further comprising providing a central processor and an interconnection in order to network one or more controllers.

11. The method according to claim 10 wherein the interconnection is wireless.

12. A method reducing energy consumption by retrofitting a preexisting single zone constant volume HVAC system that provides heating, cooling, and/or ventilation to an indoor space within a single zone of a building that has periodic occupancy, wherein the heating, cooling, and/or ventilation is initiated based upon preset conditions or on occupancy command and wherein the preexisting HVAC system includes a preexisting fan assembly having a fan and a fan motor that operates in a range of not operating to a maximum operation, a thermostatic device, heating assembly and cooling assembly having preexisting equipment control terminations, and an economizer assembly comprised of at least one outside air and one return air damper with an associated damper actuator;

the energy reducing method comprising;

providing a programmable logic controller that can receive input from the preexisting thermostatic device and send heating, cooling, and ventilation instructions to the preexisting fan assembly for ventilating in an indoor building space in a ventilation mode, and to the heating assembly that can send heat to the same indoor building space in a heating mode, and to the cooling assembly that can send cooling to the same indoor building space in a cooling mode, and to the preexisting economizer assembly for controlling the damper actuator to control opening of the damper in an economizer mode; and

operably connecting the programmable logic controller to the preexisting equipment control terminations;

providing a variable frequency drive (VFD), controlled by the programmable logic controller, and operably connecting the VFD to the fan motor;

providing an input sensor to sense outside air and return air conditions and return economizer air and the sensors communicate their sensed conditions to the programmable logic controller;

operating the HVAC system in the ventilation mode, the a heating mode, the cooling mode, and the economizer mode controlled by the programmable logic controller, and operating the fan motor at a reduced speed during the ventilation mode when less than maximum ventilation is required and operating the fan motor at a reduced speed during the heating and/or cooling mode; and

providing fault detection via a discharge air sensor and/or a current status switch.

13. The method according to claim 12 wherein the fault detection further comprises interconnecting a fan fault and a heat/cool (temperature-based) fault.

14. The method according to claim 12 further comprising running the fan fault detection first and then running the heat/cool (temperature-based) fault detection;

wherein an energy consumption fault is added and is independent of the fan fault and the heat/cool (temperature-based) fault detection.

15. The method according to claim 12 wherein further energy savings are gained by operating the economizer in response to monitoring outside air and return air to determine a preferred source for cooling operations.

16. The method according to claim 12 wherein further energy savings are gained by closing the at least one outside air damper during the unoccupied heating modes.

17. The method according to claim 12 wherein further energy savings are gained by integrating the economizer and cooling operations.

18. The method according to claim 12 wherein the fan speed is reduced in the range of 10% to 90% in the ventilation mode.

19. The method according to claim 12 wherein the fan speed is reduced in the range of 1%-30% in the heating and/or cooling mode.

20. The method according to claim 12 wherein the programmable logic controller senses one of the following:

temperature, enthalpy, or dew point in the economizer mode.

21. The method according to claim 12 wherein the programmable logic controller and VFD are incorporated into a single unit.

22. The method according to claim 12 further comprising providing a central processor and an interconnection in order to network one or more controllers.

23. The method according to claim 22 wherein the interconnection is wireless.