ENERGY REDUCING RETROFIT METHOD AND APPARATUS FOR A CONSTANT VOLUME HVAC SYSTEM

• US 20110046790A1
• Filed: 08/20/2009
• Published: 02/24/2011
• Est. Priority Date: 08/20/2009
• Status: Active Grant

• Current Assignee: Pro Star Energy Solutions LLC
• Original Assignee: Performance Heating & Air Conditioning Inc
• Inventors: Miller, Danny, Sipe, Justin
• Granted Patent: US 8,515,584 B2
• Time in Patent Office: Days
• 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 for the reduction of fan speed in the heating and cooling modes. 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. The fan speed may be further reduced upon a reduction in sensed occupancy levels of the space, such as with a CO₂ sensor. Additionally, the fan speed may be reduced in the heating and/or cooling mode to further reduce energy consumption. The controller may also be programmed and equipped with sensors to allow simultaneous mechanical compressor cooling and economizer free cooling operation, for the operation of the economizer in response to the monitoring of outside air and return air to determine the preferred source for cooling operations, to keep the outside air damper closed during the unoccupied heating modes such as morning warm-up, and/or to provide fault detection. The retrofit method and apparatus may be employed in a stand-alone or networked version.

Claims

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

heating, cooling, or ventilation to a space within a building that has at least partial occupancy, wherein the heating, cooling, or ventilation is based on preset conditions or on occupancy command and wherein the preexisting HVAC system consists of a fan, a fan motor, a thermostatic device, heating and/or cooling equipment having 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 fan assembly for ventilating a space in a building, and to a heating assembly that can send heat to the same building space, and to a cooling assembly that can send cooling to the same building space; and

operably connecting it to the existing equipment control terminations;

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

operating the HVAC system in a ventilation mode, a heating mode, a cooling mode, controlled by the controller; and

operating the fan motor at a reduced speed during the ventilation mode when the less than maximum ventilation is required.

2. The method according to claim 1 wherein the operating the fan motor at a reduced speed during the heating and/or cooling mode.

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

4. The method according to claim 2 wherein the fan speed is reduced in the range of 1%-30% in the heating and/or cooling mode.

5. The method according to claim 1 further comprising providing an occupancy sensor to determine occupancy levels within the building space and sending the sensed occupancy level to the controller;

and operating the fan motor at a reduced speed during the ventilation mode when the occupancy level requires less than maximum ventilation.

6. The method according to claim 5 wherein the fan speed is reduced in the range of 10% to 90% in the ventilation mode in response to the sensed occupancy needs.

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

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

9. The method according to claim 8 wherein the interconnection is wireless.

10. The method according to claim 8 further comprising providing a discharge air sensor and/or a current status switch in order to provide fault detection.

11. A method reducing energy consumption by retrofitting a constant volume HVAC system that provides heating, cooling, and/or ventilation to a space within a building that has at least partial occupancy, wherein the heating, cooling, and/or ventilation is based on preset conditions or on occupancy command and wherein the preexisting HVAC system consists of a fan, a fan motor, a thermostatic device, heating and cooling equipment having equipment control terminations, and an economizer 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 thermostatic device and send heating, cooling, and ventilation instructions to a fan assembly for ventilating a space in a building (ventilation mode), and to a heating assembly that can send heat to the same building space (heating mode), and to a cooling assembly that can send cooling to the same building space (cooling mode), and to the system economizer (economizer mode); and

operably connecting it to the existing equipment control terminations;

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

providing an occupancy sensor to determine occupancy levels within the building space and sending the sensed occupancy level to the controller for at least the ventilation mode, heating mode, and cooling mode;

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

operating the fan motor at a reduced speed during the ventilation mode when the occupancy level requires less than maximum ventilation;

operating the fan motor at a reduced speed during the heating and/or cooling mode;

operating the HVAC system in a ventilation mode, a heating mode, a cooling mode, and economizer mode controlled by the controller;

12. The method according to claim 11 wherein further energy savings are gained by the operation of the economizer in response to the monitoring of outside air and return air to determine the preferred source for cooling operations.

13. The method according to claim 11 wherein further energy savings are gained by closing the at least one outside air damper during the unoccupied heating modes.

14. The method according to claim 11 wherein further energy savings are gained by integrating the economizer and cooling operations.

15. The method according to claim 11 wherein the fan speed is reduced in the range of 10% to 90% in the ventilation mode.

16. The method according to claim 11 wherein the fan speed is reduced in the range of 1%-30% in the heating and/or cooling mode.

17. The method according to claim 11 wherein the controller senses one of the following:

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

18. The method according to claim 11 wherein the controller and VFD are incorporated into a single unit.

19. The method according to claim 11 further comprising providing a central processor and interconnected in order to network one or more controllers.

20. The method according to claim 19 wherein the interconnection is wireless.

21. The method according to claim 19 further comprising providing a discharge air sensor and/or a current status switch in order to provide fault detection.

22. An efficiency enhancing controller (EEC) for HVAC constant volume systems;

the EEC comprising;

a programmable logic controller that can receive input signals from sensors and a thermostatic device and send control heating, cooling, and ventilation instructions to a fan assembly for ventilating a space in a building, and to a heating assembly that can send heat to the same building space, and to a cooling assembly that can send cooling to the same building space;

a variable frequency drive (VFD) that receives signals from the controller and can control the frequency of a fan motor of the fan assembly;

an occupancy sensor for measuring the level of the building space occupancy and has the capability of sending the sensed occupancy of the building space to the controller;

wherein the controller has the capability to reduce the fan motor speed via the VFD when the building space is not fully occupied.