Abstract:
An HVAC system where either/both the heating apparatus or cooling apparatus are single or multistage and controlled by a thermostat capable of single or multistage operation through two connecting wires. A single control wire is repurposed to act as a “C” common wire to provide a return path for current in order to power a room thermostat. A code is transmitted via a wireless signal to a receiving microcontroller located in the HVAC heating or cooling unit. The receiving microcontroller interprets the signal and provides power, via relays, from the transformer to the appropriate terminal in the heating control thereby replacing the function of the repurposed wire. In essence, the wireless transmission in combination with a relay, replace the function of the white wire allowing it to be repurposed to a C wire. There is no possibility of a false trigger that commonly exists in shared wire systems.

Description:
STATEMENT REGARDING FEDERALLY SPONSORED R&amp;D 
       [0001]    None. 
       NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0002]    None. 
       CROSS REFERENCE TO RELATED APPLICATIONS 
       [0003]    None 
       BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
       [0004]    The present invention relates generally to the control of heating, ventilating and air conditioning (HVAC) systems and more particularly to both one and multistage systems having insufficient wiring between a room thermostat and the system control. 
       2. Description of the Prior Art 
       [0005]    In the last few years, the function and capability of room thermostats has increased. Room thermostats can now attach to Wi-Fi networks, communicate with remote sensors and display detailed information on LED screens with high resolution and backlighting. The result is a substantial increase in power requirements exceeding the capability of battery power alone. New modern smart thermostats require a “C” or common wire, it provides an independent return path for current that enables a room thermostat to be powered from an existing transformer that is typically located in the HVAC unit. However, many homes have only two control wires for their single stage system. The system is activated when the circuit is completed between the two wires. It is often not cost effective or practical to run more wires from the room thermostat to the HVAC unit since they are generally located within partition walls. This is especially true in multi-story dwellings and dwellings with masonry interior walls. This can serve as a reason for not upgrading existing equipment and it prevents the homeowner from enjoying the benefits of higher efficiency and greater comfort. 
         [0006]    In U.S. Pat. No. 8,511,577 an arrangement called power stealing is discussed where power is taken from the same selected call relay wire that is used to call for an HVAC function. This method is not 100% effective as it is common for the heating or cooling system to activate after erroneously being triggered by the power stealing activity. In U.S. Pat. No. 9,086,703 active power stealing and inactive power stealing are introduced as a way to minimize erroneous triggering. Despite advancements false triggering remains a problem. 
         [0007]    In U.S. Pat. No. 6,566,768 an arrangement is discussed where power sharing is applied to a two power line thermostat control. This arrangement and the patents cited above are deficient in that they do not allow the user to independently control the fan on/off and high/low modes. It is common for home owners to use the fan on/off and high/low modes for circulation purposes only, without heating or cooling the air. 
         [0008]    Additionally, HVAC units with two stage systems are becoming more common. These two stage systems provide greater comfort and greater efficiency by having low and high output operating modes. Two stage room thermostats require an additional control wire, in addition to a “C” common wire, between it and the HVAC heating/cooling equipment. This additional wire controls the high/low function in the HVAC unit, with one wire necessary for cooling and another for heating. 
         [0009]    In U.S. Pat. No. 6,450,409, a method is described to overcome wiring limitations encountered when a one stage HVAC system is replaced with a two stage system. A single wire is used to convey control information to the HVAC unit. This is not an ideal solution as a single wire is performing multiple purposes and might falsely trigger the HVAC unit into an active state. This method also does not allow the user to independently control the fan on/off and high/low modes. It is common for home owners to use the fan on/off and high/low modes for circulation purposes only without heating or cooling the air. 
       SUMMARY OF THE INVENTION 
       [0010]    It is an object of the present invention to provide a method and apparatus to overcome the limitations of the prior art described above. Briefly, in accordance with the invention, a single control wire is repurposed to act as a “C” common wire to provide a return path for current in order to power a room thermostat. A microcontroller accepts input from the room thermostat output terminals and firmware in the microprocessor determines the appropriate code to transmit via a wireless signal to a receiving microcontroller located in the HVAC heating or cooling unit. The receiving microcontroller interprets the signal and provides power, via relays, from the transformer to the appropriate terminal in the heating control thereby replacing the function of the repurposed wire. In essence, the wireless transmission in combination with a relay, replace the function of the white wire allowing it to be repurposed to a C wire. There is no possibility of a false trigger that commonly exists in shared wire systems. 
         [0011]    It is also a further object of the present invention to provide a method and apparatus for connecting any single or multistage room thermostat to any single or multistage HVAC unit, in buildings that lack a sufficient number of wires (minimum of two required), in a convenient and cost effective way, enabling homeowners to fully access the replacement market to upgrade their HVAC equipment. 
         [0012]    It is still further an object of the present invention to independently control the fan on/off/high/low fan functions in order for the user to have the ability to circulate air without heating or cooling it. 
         [0013]    It is still a further object of the present invention to incorporate the transmitter unit ( 2 ) into another device (patent application Ser. No. 14/741,269) since they have similar components, in order to make that device operable with any room thermostat. This combination will provide homeowners with a comprehensive, convenient, and cost effective way to fully access the replacement market and upgrade their HVAC equipment to enjoy higher efficiency and increased comfort. A homeowner will be able to install and operate any room thermostat, including a smart thermostat, with single or multistage capability, using as little as two existing wires, and still retain the ability to independently control the fan on/off/high/low fan functions, without any risk of false triggering, all without adding additional wiring. 
         [0014]    It is also an object of the present invention that it may be used in the presence of more than two control or power lines. The design disclosures present the skilled person with a wide range from which to choose appropriate obvious modifications. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is an overall view of the present invention components and their respective placement and manner of connection according to some embodiments. The sensor/transmitter unit ( 2 ) is hard wired to a thermostat ( 1 ), and the receiver unit ( 3 ) is located in the furnace ( 3 ) and hard wired to the furnace control board ( 5 ). 
           [0016]      FIG. 2  is an exploded view of the Sensor/Transmitter unit ( 2 ) of the present invention and its&#39; general internal components according to some embodiments. 
           [0017]      FIG. 3  is an exploded view of the receiver unit ( 3 ) of the present invention and its&#39; general internal components according to some embodiments. 
           [0018]      FIG. 4  is a schematic of the connection between the existing furnace control board ( 5 ) and the furnace receiver unit ( 3 ) of the present invention according to some embodiments. 
           [0019]      FIG. 5  is a schematic of the present invention and its expected integration with the Heating and Cooling Control System (HCCS) according to some embodiments. This figure shows the physical connection between the combined devices and a typical room thermostat. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     1. Definitions 
       [0020]    Wirelessly or wireless as used herein shall mean any radio frequency, Bluetooth, Wi-Fi, or other over the air technology. 
         [0021]    HCCS—as used herein shall mean the Heating and Cooling Control System patent application Ser. No. 14/741,269. 
         [0022]    24 VAC—as used herein shall mean any voltage commonly produced by transformers labeled as 24 VAC (19-38 VAC). 
         [0023]    120 VAC—as used herein shall mean any voltage commonly available and identified as such in the United States. 
         [0024]    Transceiver—a device comprising both a wireless transmitter and a wireless receiver which are combined and share common circuitry or a single housing. 
         [0025]    Transmitter—a device that transmits signals wirelessly via radio frequency, Wi-Fi, Bluetooth, or any other over the air technology. 
         [0026]    Receiver—a device that receives signals wirelessly via radio frequency, Wi-Fi, Bluetooth, or any other over the air technology. 
         [0027]    Firmware—software that is programmed into a computer chip to perform basic instructions. 
         [0028]    Power circuit—a section devoted to housing, providing, acquiring, or converting power to operate the respective device. This may include a transformer and/or a battery. 
         [0029]    Conversion circuit—a section devoted to housing, providing, acquiring, or converting power signals from the thermostat to enable the microprocessor to read and execute the appropriate commands as specified in the firmware. 
         [0030]    LED—Light Emitting Diode, a multi lead semiconductor light source that is used as an indicator lamp to alert the user of certain events. 
         [0031]    Microprocessor—Central processing unit (CPU) on a single silicon chip (called microchip) that can be ‘soft wired’ by using different programming instructions (firmware) 
         [0032]    Transformer—an apparatus for reducing or increasing the voltage of an alternating current. This device is typically located in an HVAC unit to power the various components and reduces voltage from 120 VAC to 24 VAC. 
         [0033]    Thermostat—a device that automatically regulates temperature, or that activates a device when the temperature reaches a certain point. A thermostat may also include devices where power is stored by capacitance or in rechargeable batteries. 
         [0034]    Relay—A device that responds to a small current or voltage change by activating switches or other devices in an electric circuit. 
       2. Best Mode of the Invention 
       [0035]      FIG. 1  shows a front view of the best mode contemplated by the inventor of the present invention. The present invention includes both a sensor/transmitter unit ( 2 ) and a receiver unit ( 3 ). As shown, the transmitter/sensor unit ( 2 ) is mounted adjacent to a room thermostat ( 1 ), with wires extending from the present invention to either all or some of the appropriate thermostat terminals. Any number or combination of room thermostat terminals may be used based on the needs of the user and capabilities of the room thermostat. For illustration purposes a furnace is shown in the drawings but any HVAC unit can be substituted. The other half of the present invention is the receiver unit ( 3 ) that is mounted in the HVAC unit or furnace ( 4 ), adjacent to the furnace control board ( 5 ). The present invention allows a user to install and use a room thermostat that requires an additional C wire despite the fact that only two wires are available. The white wire is repurposed to act as a C wire, thus providing a return path for current which completes the circuit and provides power to operate a thermostat requiring a C wire. The thermostat sensor/transmitter unit ( 2 ) will transmit the appropriate signal wirelessly to the furnace receiver which activates the appropriate furnace function (furnace ON, HIGH speed blower, LOW speed blower etc). In essence, the wireless transmission in combination with a relay, replace the function of the white wire allowing it to be repurposed to a C wire. 
         [0036]      FIG. 2  shows a front section view of the transmitter unit ( 2 ) of the present invention and its&#39; major components. These include power circuit ( 12 ), microprocessor ( 7 ), conversion circuit ( 8 ), wireless transmitter ( 9 ), wireless receiver ( 10 ), and various switches (toggle/rocker ( 13 ), dip ( 14 ), etc) and LED&#39;s ( 15 ). A transceiver ( 11 ) may be substituted for the separate wireless transmitter ( 9 ) and wireless receiver ( 10 ). These and other minor components are housed in an enclosure ( 2 ). 
         [0037]      FIG. 3  shows a front section view of the receiver unit ( 3 ) of the present invention and its&#39; major components. These include power circuit ( 21 ), microprocessor ( 16 ), conversion circuit ( 17 ), wireless transmitter ( 18 ), wireless receiver ( 19 ) and various switches (toggle/rocker ( 22 ), dip ( 23 ), etc), relays ( 24 ), and LED&#39;s ( 25 ). A radio transceiver ( 20 ) may be substituted for the separate wireless transmitter ( 18 ) and wireless receiver ( 19 ). The number of relays ( 24 ) is dependent on the capability of the room thermostat and needs of the user (furnace ON, HIGH speed blower, LOW speed blower etc). These and other minor components are housed in an enclosure ( 3 ). 
         [0038]      FIG. 4  shows a front section view of the receiver unit ( 3 ) of the present invention in a furnace ( 4 ). The receiver unit ( 3 ) is attached via wires to the existing furnace control board or terminal. The control board or terminal will typically have terminal identifiers labeled B, C, T, R, Rc, G, W, W2, Y, Y2. B, Blue, Black, or T represents the C—Common wire which provides a return path to the transformer for current from the Red wire. Red—R—represents 24 VAC power from the furnace&#39;s transformer. Red—Rc—24 VAC represents power provided to enable cooling functions, Green—G—represents fan operation, White—W, W2—represents heat functions high and low, Yellow—Y, Y2—represents air conditioner functions high and low. Terminals W2 and Y2 exist on some furnaces to enable high/low speed fan/blower motor operation. Since there are no standards for wire color, and any wire can be used for any purpose, the use of a repurposed “white” wire is only for illustration purposes. Connections for other HVAC functions such as compressor, heat pump etc can be accommodated as needed. 
       3. How to Make the Invention 
       [0039]    As can be seen from the drawings the present invention consists of two parts, a sensor/transmitter ( 2 ) and a receiver ( 3 ). The internal components of both parts are similar and consist of a power circuit ( 12 ), microprocessor ( 7 ), conversion circuit ( 8 ), wireless transmitter ( 9 ), wireless receiver ( 10 ), and various switches (toggle/rocker ( 13 ), dip ( 14 ), etc), and LED&#39;s ( 15 ). A transceiver ( 11 ) may be substituted for the separate wireless transmitter ( 9 ) and wireless receiver ( 10 ). The receiver unit will also house multiple relays. These and other minor components are housed in an enclosure ( 2 ). Customization is accomplished via firmware and through the use of various functions of the microprocessor, as well as through the use of relays. The receiver units are customized to perform the commands that are sent by the sensor/transmitter. Many configurations are possible based on the desired functions and capability of the room thermostat. 
       4. How to Use the Invention 
       [0040]    The present invention, consisting of a sensor/transmitter module and a receiver module contain similar components and consist of a power circuit ( 12 ), microprocessor ( 7 ), conversion circuit ( 8 ), wireless transmitter ( 9 ), wireless receiver ( 10 ), and various switches (toggle/rocker ( 13 ), dip ( 14 ), etc), and LED&#39;s ( 15 ). A transceiver ( 11 ) may be substituted for the separate wireless transmitter ( 9 ) and wireless receiver ( 10 ). The receiver unit will also house multiple relays. These and other minor components are housed in an enclosure ( 2 ). Customization is accomplished via firmware and through the use of various functions of the microprocessor as well as through the use of relays. The receiver units are customized to perform the commands that are sent by the sensor/transmitter. Many configurations are possible based on the functions that are desired. In accordance with the present invention, a single control wire (white) is repurposed to act as a “C” common wire to provide a return path for current, completing the circuit and thereby providing power to the room thermostat. The user must reconnect the white wire in the furnace from the W terminal to the terminal labeled B, C, or T. The other end of the white wire is then reconnected from the W room thermostat terminal to the B or C thermostat terminal. Typically a white and red wire are available to the user, but since there are no standards for wire color, and any wire can be used for any purpose, the use of a repurposed “white” wire is only for illustration purposes. The sensor/transmitter module is mounted adjacent to the thermostat and hard wired to it. When the microprocessor receives input from the thermostat output terminals it will transmit a wireless signal to the receiving module located in the furnace. The microprocessor in the receiving module interprets the signal and provides power to the appropriate relay. The relay will allow power to flow from the transformer to the appropriate terminal in the heating appliance control. For example, upon receiving a heat ON signal from the thermostat, a wireless signal will be sent from the sensor/transmitter module to the receiver module. Upon receiving the wireless signal, the receiver module will activate the heat ON relay (typically W—white wire), allowing the relay to power the heat ON cycle. This illustrates how the present invention replaces the W repurposed wire with a wireless signal and a relay. Other relays can be added to control W2—high speed heat ON, G—Fan only ON, compressor, heat pump, etc. It is planned that the present invention will be integrated into another device, the Heating and Cooling Control System (HCCS) (patent application Ser. No. 14/741,269), in order to make that invention available to users who do not have a C wire. The invention should not be considered as limited to the specific embodiment depicted, but rather as defined in the claims.