Systems and Methods for Air Temperature Control Using A2l Refrigerants

This application is a continuation application of U.S. application Ser. No. 18/435,356 filed Feb. 7, 2024, entitled “SYNSTEMS AND METHODS FOR AIR TEMPERATURE CONTROL USING A2L REFRIGERANTS”, which is a continuation application of U.S. application Ser. No. 17/164,575 filed Feb. 1, 2021, entitled “SYSTEMS AND METHODS FOR AIR TEMPERATURE CONTROL USING A2L REFRIGERANTS,” issued as U.S. Pat. No. 11,920,805 which are all incorporated herein by reference in their entirety.

The present invention relates to heating, ventilation, and air-conditioning (HVAC) systems, and more particularly to HVAC systems using an American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) Standard 34 classified “A2L” refrigerant.

Modern residential and industrial buildings use HVAC systems to keep indoor spaces climate controlled. In general, HVAC systems circulate air over low-temperature or high-temperature sources and distribute the cooled or heated air throughout the building to adjust the indoor ambient air temperature. Modern HVAC systems have used the well-known physical principle that a fluid transitioning from gas to liquid releases heat, while a fluid transitioning from liquid to gas absorbs heat, in order to efficiently cool or heat the air before distribution. Typical HVAC systems circulate a fluid refrigerant through a closed loop of tubing, using compressors and other devices to manipulate the refrigerant and cause it to cycle between its liquid and gas phases. Generally, these phase transitions occur within the HVAC's evaporator and condensing coils, which are part of the closed loop and designed to transfer heat between the circulating refrigerant and flowing ambient air.

For a long time, HVAC systems used, and in some places continue to use, a chemical called R-12 or a chemical called R-22 as the refrigerant in the system. While R-12 and R-22 are both classified as “A1” refrigerants under ASHRAE Standard 34, which means they are non-flammable and have lower toxicity, they both posed great threats to the ozone and environment. R-22, while an improvement over R-12 in that it had a much lower ozone depletion potential (ODP) (0.05 for R-22 compared to 1.0 for R-12) and global warming potential (GWP) (1,760 for R-22 compared to 10,200 for R-12), still had adverse effects on the ozone and environment. Thus, in an attempt to solve the ozone depletion issue, the industry, with the help of regulations, began transitioning to the use of R-410A, which is another A1 refrigerant but with an ODP of 0. However, R-410A has a GWP (2,088) that is even higher than that of R-22.

Thus, in an attempt to solve the global warming issue created by the use of the above refrigerants, the industry has begun to move from the use of A1 refrigerants to those classified as A2L refrigerants, which means that the refrigerants are still low toxicity but instead of being non-flammable, they have very low flammability. Generally, these A2L refrigerants have much lower GWP than the A1 refrigerants currently and previously used while still having an ODP of 0 like R-410A. Some examples of viable A2L refrigerants include, but are not limited to, R-32 and R-454b, both of which have an ODP of 0 and a GWP of 675 and 466, respectively. However, this now means that HVAC systems incorporating these A2L refrigerants need to employ safety measures to make sure that the refrigerants do not ignite in case there is a leak of A2L refrigerant. Some of these safety requirements for systems using A2L refrigerants include turning on a blower in the HVAC system while shutting off all other components of the HVAC system within the requisite time after detection of an A2L refrigerant leak as required by A2L safety standards. Present HVAC systems are not only unable to achieve these requirements within the required time, but they are unable to detect A2L leaks.

The present invention is directed to an HVAC system for controlling an air temperature in a building and a method of installing the HVAC system in the building. In one or more embodiments, the HVAC system uses an ASHRAE Standard 34 classified “A2L” refrigerant. In one or more embodiments, the HVAC system includes an indoor unit, a blower, an outdoor unit, an A2L circuit board, and one or more A2L sensors. The indoor is disposed inside the building and has a heat exchanger that uses the A2L refrigerant. The blower is disposed within and electrically coupled to the indoor unit. The outdoor unit is disposed outside the building, and in one or more embodiments, the outdoor unit is electrically coupled to the indoor unit. The A2L control board is electrically coupled to the indoor unit, to the one or more A2L sensors, and, in one or more embodiments, to the blower. Additionally, the one or more A2L sensors are configured to detect an amount of A2L refrigerant. In one or more embodiments described herein, the A2L control board is configured to power on the blower and power off the indoor unit and the outdoor unit when the one or more A2L sensors detect the amount of the A2L refrigerant exceeds a leak threshold.

The method of installing the HVAC system in the building includes disposing the indoor unit inside the building and disposing the outdoor unit outside the building. Further, the blower is disposed within the indoor unit and electrically coupled to the indoor unit. Furthermore, in one or more embodiments, the outdoor unit is electrically coupled to the indoor unit. Additionally, the A2L control board is electrically coupled to the indoor unit, to the one or more A2L sensors, and in one or more embodiments, to the blower. In one or more embodiments described herein, if the one or more A2L sensors detect that the amount of the A2L refrigerant exceeds the leak threshold, then the A2L control board may power on the blower and power off the indoor unit and the outdoor unit.

The HVAC systems as disclosed herein provide components and architecture that allow for detection of leaks of A2L refrigerant and for meeting the safety requirements within the required time. Thus, HVAC systems incorporating A2L refrigerants may be installed such that they operate safely while reducing the negative environmental impact caused by present HVAC systems. The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular description of the invention, as illustrated in the accompanying drawings, wherein like reference numbers represent like parts of the invention.

This disclosure generally relates to non-communicating and communicating HVAC systems designed to incorporate the use of an A2L refrigerant and meet the safety standards imposed on systems using A2L refrigerants.

shows a non-communicating HVAC system using an A2L refrigerant, according to one or more embodiments. In one or more embodiments, an HVAC systemmay be used to distribute cooled or heated air throughout a buildingto adjust the ambient air temperature insideof the building. The HVAC system may include an indoor unit, an outdoor unit, a thermostat, an A2L control board, and an A2L sensor. Generally, in one or more embodiments, the indoor unitmay be fluidly coupled to the outdoor unitsuch that an A2L refrigerant may flow between the indoor unitand the outdoor unitto cool or heat air within the indoor unit. Further, in one or more embodiments, both the indoor unitand the outdoor unitmay be electrically coupled to the thermostat. The thermostatmay be configured to use on/off-type signals for communication and control of the indoor unitand the outdoor unit. Furthermore, in one or more embodiments, the A2L control boardmay be directly electrically coupled to the indoor unitand the A2L sensor. The A2L control boardmay act as a passthrough for power to portions of the indoor unit, the outdoor unit, and the thermostatand may be configured to block power from getting to certain parts of the indoor unit, the outdoor unit, and the thermostatif there is an A2L refrigerant leak in the system. Additionally, an A2L sensormay be physically disposed within the indoor unitand electrically coupled to the A2L control board. The A2L sensormay be configured to send signals to the A2L control boardwhen an A2L refrigerant leak is detected.

In one or more embodiments, indoor unitmay be disposed on the insideof the building. The indoor unitmay be configured to distribute cooled or heated air to rooms on the insideof the building. The indoor unitmay be any type of HVAC system that includes a blowerand a heat exchangerhaving an indoor evaporator coil. Thus, in one or more embodiments, the indoor unitmay be either a furnace or an air handler, as both types of system include, at least, a blower and an indoor evaporator coil. Additionally, the indoor evaporator coilmay be disposed adjacent to the blower, such that when the blowerblows air within the indoor unit, the air is blown through the evaporator coil.

Further, in one or more embodiments, the blowermay include a blower fanand a blower motor. By way of example, in one or more embodiments, the blower motormay be constant torque motor, while in other embodiments, the blower motormay be a permanent split capacitor (PSC) motor. The blower motormay be mechanically coupled to the blower fansuch that when the blower motoris turned on, the blower fanis configured to spin and cause a movement of air out from the blowerand through the indoor evaporator coil. The indoor evaporator coilmay be configured to receive the A2L refrigerant on the inside of the coil while air from the bloweris blown across the outside of the coil, which allows for heat to exchange either from the A2L refrigerant to the air or vice versa. The A2L refrigerant, after cooling or heating the air, may be cycled back to the outdoor unit, where it will go through the reverse heat exchange process before returning to the indoor evaporator coil. Additionally, indoor unitis configured to distribute the air that is blown from the blowerand across the indoor evaporator coilto the rooms on the insideof the buildingby way of the force of the blower.

The indoor unitmay also include a transformerand an indoor control board. The transformermay be directly electrically coupled to and configured to provide 24 volts A/C power to the A2L control board. Further, the indoor control boardmay be electrically coupled to the A2L control boardsuch that the indoor control boardmay receive 24 volts A/C power indirectly from the transformer. Additionally, the indoor control boardmay be electrically coupled to, at least, the blower motorand the thermostat. In one or more embodiments, the transformermay be configured to indirectly provide a 24 volt A/C power to both the blower motorand the thermostatby way of indoor control boardand the A2L control board. In one or more embodiments, the blower motor has its own source of power. So, while the 24 volt A/C power that the blower motor receives does not power on the blower motor, the 24 volt A/C signal is needed to turn the blower motoron. By way of example only, in one or more embodiments, the indoor control boardmay be configured to provide power to the thermostat, the thermostatmay be configured to send a signal to the indoor control boardto turn on the blower motor, and the indoor control boardmay be configured to provide power to the blower motorto turn it on.

Further, the outdoor unitmay be disposed on an outsideof the buildingand be configured to use the outdoor environment to reheat or cool down the A2L refrigerant after it has been run through the indoor evaporator coil. The outdoor unitmay include, but is not limited to, either a heat pump or an air conditioner. Whether the outdoor unitis a heat pump or an air conditioner, the outdoor unitmay include a compressor (not shown), an outdoor coil (not shown), and an outdoor control board. The outdoor unitmay be configured to receive power through the outdoor control board, which itself is configured to receive power from the transformerby way of the thermostat, the indoor control board, and the A2L control board. By way of example only, in one or more embodiments, the outdoor control boardmay be configured to receive power and control signals from the thermostat, such that outdoor control boardmay start the condenser after receiving a signal from the thermostatto do so.

Still referring to, in one or more embodiments, the A2L sensormay be configured to detect an A2L refrigerant leak and send a signal reporting as much. In one or more embodiments, the A2L sensormay be configured to detect an A2L refrigerant leak by one of a number of methods, including, at least, by detecting an amount or a concentration of A2L refrigerant in the air that exceeds a leak threshold. The A2L sensormay be electrically coupled to and communicate with the A2L control board. In one or more embodiments, the A2L sensormay be electrically coupled to the A2L control boardby way of a first sensor connector. The A2L sensormay be configured to communicate to the A2L control boardthat the A2L sensoris connected to the system and working properly. Additionally, when the A2L sensordetects an A2L refrigerant leak, it may communicate the A2L refrigerant leak to the A2L control board, which may be configured to receive the signal and perform the safety measures required by A2L safety standards. In one or more embodiments, the A2L sensorand the A2L control boardmay be electrically coupled by way of an RS-485 bus; however, one of ordinary skill in the art would understand that any type of electrical connection that allows the A2L sensorto send a signal to the A2L control boardmay be used.

While the A2L sensoris depicted as being electrically and communicatively coupled to the A2L control boardby way of a wired connection, one of ordinary skill in the art would understand that the A2L sensormay just be communicatively coupled to the A2L control boardwirelessly. In one or more embodiments, the A2L sensormay be communicatively coupled to the A2L control boardby any wireless means, such as Wi-Fi or Bluetooth.

Further, in one or more embodiments, the A2L sensormay be disposed within the indoor unitso that it may detect an A2L refrigerant leak that occurs within the indoor evaporator coilof the HVAC system. As depicted, in one or more embodiments, the A2L sensormay be disposed directly against the indoor evaporator coil to minimize the time it takes for the A2L sensorto detect an A2L refrigerant leak. Further, while the A2L sensoris depicted within the indoor unit, one or ordinary skill in the art would understand that the A2L sensormay instead be disposed within the outdoor unit. Further, while a single sensor is depicted, one of ordinary skill in the art would understand that multiple sensors may be incorporated into the HVAC system to ensure that an A2L refrigerant leak is detected and the required safety measures are taken within the time required by A2L safety standards. For example, one of ordinary skill in the art would understand that the HVAC system may include two A2L sensors, with both A2L sensors disposed within the indoor unit, both A2L sensors disposed within the outdoor unit, or one A2L sensor disposed within each of the indoor unit and the outdoor unit. Thus, one of ordinary skill in the art would understand that in one or more embodiments, a plurality of A2L sensors may be disposed within the HVAC system with one or more A2L sensors disposed within the indoor unit and/or one or more A2L sensors disposed within the outdoor unit as may be determined necessary to ensure that an A2L refrigerant leak is detected and the required safety measures are taken within the time required by A2L safety standards.

Additionally, referring to, in one or more embodiments, the A2L control boardmay be disposed inside of the indoor unit. However, one of ordinary skill in the art would understand that, in one or more embodiments, the A2L control boardmay be disposed outside of the indoor unitand either connected to the indoor unitor adjacent to the indoor unit. Further, in addition to being electrically coupled to the transformer, the indoor control board, and the A2L sensor, as discussed above, the A2L control boardmay be electrically coupled to the blower motor. In one or more embodiments, the A2L control boardmay be configured to signal the blower motorto run either by way of a 24 volt A/C line connected to an input leadon the blower motor, if the blower motoris a constant torque motor, or by way of a line voltage provided to the input leadof the blower motor, if the blower motoris a PSC motor.

In one or more embodiments, the A2L control boardmay include a power supply, a power-in contact point, a first relay, a first power-out contact point, a second relay, a second power-out contact point, a first sensor connector, a second sensor connector, a buzzer, a light emitting diode (LED), a dry contact relay, first and second ventilator contact pointsand, and a fuse. The power supplymay be coupled to circuitry on the A2L control boardsuch that the A2L control board may open and close, at least, the first relay, the second relay, and the dry contact relay. Further, in one or more embodiments, the first relaymay be electrically disposed between the power-in contact pointand the first power-out contact point, such that when the first relayis open, power from the power-in contact pointdoes not reach the first power-out contact point. Furthermore, the fusemay be electrically disposed between the power-in contact pointand the first relay. Similarly, in one or more embodiments, the second relaymay be electrically disposed between the power-in contact pointand the second power-out contact point, such that when the second relayis open, power from the power-in contact pointdoes not reach the second power-out contact point. Additionally, the fusemay be electrically disposed between the power-in contact pointand the second relay. By way of example, in one or more embodiments, when the first relayis open, the second relayis closed, and when the second relayis open, the first relayis closed. Further, in one or more embodiments, in the default state, the first relayis open and the second relayis closed.

In one or more embodiments, the transformermay be electrically coupled to the power-in contact point, the first power-out contact pointmay be electrically coupled to the indoor control board, and the second power-out contact pointmay be electrically coupled to the blower motor.displays a default state of the A2L control board, where the 24 volt A/C power coming from the transformeris routed to the blower motor, causing it to run. Further, in one or more embodiments, if the A2L control boardfails, the relays all revert to their default state, and thus, if the A2L control boardfails, power will be directed to the blower motor. Furthermore, in one or more embodiments, when the A2L control boardis turned on, the second relayimmediately opens so that the blower motoris not unnecessarily run. Additionally, after the A2L control boardis turned on, when the system is ready to run, the first relayis closed, turning on the HVAC system.

Further, in one or more embodiments, the power supplymay be coupled to the first sensor connectorand the second sensor connector, separately. Thus, in one or more embodiments, the A2L control boardmay separately test one or more A2L sensorsbefore closing the first relayand powering up the HVAC system. This allows for the A2L control boardto make sure that the sensorsare working properly and there are no A2L refrigerant leaks before beginning the system. While two separate sensor connectors are depicted, one of ordinary skill in the art would understand that the A2L control board may instead include a sensor signal-in contact and a sensor signal-out contact and the one or more sensors may be run in series instead of in parallel.

Thus, when the A2L control boardreceives a signal from the A2L sensorthat there is an A2L refrigerant leak, the A2L control boardmay be configured to carry out the required safety measures required by A2L safety standards. More specifically, in one or more embodiments, if a leak is detected, the A2L control boardmay be configured to cut off power to the indoor control boardby opening the first relay, while directing power directly to the blower motorby closing the second relay. Since the indoor unit, the thermostat, and the outdoor unitreceive power from the indoor control board, when the A2L sensor detects an A2L refrigerant leak and the A2L control boardcuts power to the indoor control board, the entire HVAC system, besides the blower motor, is configured to lose power and shut off. This allows the HVAC systemto meet the A2L safety requirements within the requisite time after detection of an A2L refrigerant leak.

Additionally, as discussed above, in one or more embodiments, the A2L control boardmay include a buzzer, an LED, a dry contact relay, and first and second ventilator contact pointsand. In one or more embodiments, the dry contact relaymay be electrically coupled to a ventilator (not shown), such that when the A2L control boardreceives an A2L refrigerant leak signal from the A2L sensor, the dry contact relaywill flip and turn on the ventilator. Furthermore, in one or more embodiments, when the A2L control board receives an A2L refrigerant leak signal from the A2L sensor, the LEDand the buzzerwill receive power. When receiving power, the LEDwill display an error code and the buzzerwill make sound in order to give visual and auditory alarms that the HVAC systemis experiencing an A2L refrigerant leak.

Referring now to, a flow chart of an embodiment of a methodof installing and operating a non-communicating HVAC system using an A2L refrigerant as described above with respect to, according to one or more embodiments, is illustrated. Beginning with an HVAC systemin which the indoor unithas been disposed on an insideof a building, the outdoor unithas been disposed on an outsideof the building, the indoor control boardhas been electrically coupled to the thermostatand a blower motorof the blower, and the outdoor control boardhas been electrically coupled to the thermostat, the methodmay include one or more of the following: (step) installing the A2L control boardand the A2L sensorinto the HVAC system, (step) testing the A2L sensor, (step) beginning operation of the HVAC system, (step) checking for A2L refrigerant leaks, and (step) performing safety measures upon detecting an A2L refrigerant leak.

At step, an A2L control boardand an A2L sensormay be installed into the HVAC system. Installation of the A2L control boardand the A2L sensormay include, at least, (step) physically coupling the A2L sensorto the indoor evaporator coilof the indoor unit, (step) electrically coupling the A2L sensorto the A2L control board, (step) electrically coupling the A2L control boardto the indoor control board, (step) electrically coupling the A2L control boardto the blower motor, (step) electrically coupling the A2L control boardto the transformer, and (step) turning on the A2L control boardand opening the second relay.

In one or more embodiments, at step, the A2L sensormay be disposed within the indoor unitsuch that it is adjacent or connected to the indoor evaporator coilsuch that the A2L sensoris able to detect an A2L refrigerant leak if one occurs. Further, at step, the A2L sensormay be electrically coupled to the A2L control boardsuch that the A2L sensorand the A2L control boardhave two-way communication between them. By way of example, in one or more embodiments, an A2L sensormay be electrically coupled to a first sensor connectorof the A2L control boardby way of an RS-485 bus. One of ordinary skill in the art would appreciate that in other embodiments, any other electric coupling that allows for two-way communication between the A2L sensorand the A2L control boardmay be used.

At step, the A2L control boardmay be electrically coupled to the indoor control board. In one or more embodiments, a wire capable of carrying 24 volt A/C power may be electrically coupled on one end to a power-in terminal within the indoor control boardand on the other end to a first power-out contactof the A2L control board. Thus, once a transformeris electrically coupled to the A2L control board, providing a 24 volt A/C power to the A2L control board, and a first relayis closed, the indoor control boardmay receive the 24 volt A/C power.

At step, the A2L control boardmay be electrically coupled to the blower motor. In one or more embodiments, a wire capable of carrying 24 volt A/C power may be electrically coupled on one end to an input leadon the blower motorand on the other end to a second power-out contactof the A2L control board. Thus, once a transformeris electrically coupled to the A2L control boardproviding a 24 volt A/C power to the A2L control board, the blower motormay receive the 24 volt A/C power whenever the second relayis closed. In one or more embodiments, the default for the second relaymay be that it is closed; however, while the HVAC system is running and no A2L leak is detected, the second relayis kept open. Further, in the event that an A2L refrigerant leak is detected, the second relayis closed such that the blower motormay receive the 24 volt A/C power even though the rest of the HVAC system is shut down.

At step, the A2L control boardmay be electrically coupled to the transformer. In one or more embodiments, a wire capable of carrying 24 volt A/C power may be electrically coupled on one end to a power-out terminal within the transformerand on the other end to a power-in contactof the A2L control board. Thus, once the transformeris electrically coupled to the A2L control board, the A2L control board has a 24 volt A/C power that it may distribute to either the indoor control boardor the blower motor.

At step, the A2L control boardmay be turned on and the second relaymay be opened. In one or more embodiments, when the A2L control boardis turned on, the relays are in the default state, which includes the second relaybeing closed. Thus, in order to make sure power is not unnecessarily diverted to the blower motor, in one or more embodiments, when the A2L control boardpowers up, the A2L control boardopens the second relay.

At step, the A2L sensormay be tested to confirm that it is properly operational. Once electrically coupled to the A2L control board, in one or more embodiments, the A2L sensormay perform an internal diagnostic check to make sure that the sensor is operating properly and may detect an A2L refrigerant leak. If the diagnostic check is successful, the A2L sensormay communicate the successful diagnostic check to the A2L control board, which can begin operation of the HVAC system. If the A2L sensorfails the diagnostic check, the A2L sensorwill communicate the failed diagnostic check to the A2L control board, which will remain in the default configuration, keeping the HVAC systemfrom operating until the A2L sensor is repaired or replaced.

At step, the A2L control boardmay begin operation of the HVAC system. In order to begin operation, in one or more embodiments, the A2L control boardmay close the first relayof the A2L control board. Closing the first relayallows for the 24 volt A/C power that the A2L control boardreceives from the transformerto pass to the indoor control boardand power up the rest of the HVAC system.

At step, while the HVAC system is running, in one or more embodiments, the A2L sensormay check for A2L refrigerant leaks. The A2L sensormay continuously check for A2L refrigerant leaks while the HVAC systemis running, such that if a check comes back negative for an A2L refrigerant leak, the A2L sensorrepeats step. However, if the AL2 sensordetects an A2L leak, then the A2L sensorcommunicates the A2L refrigerant leak to the A2L control board and the HVAC system continues to step.

At step, the HVAC system, by way of the A2L control board, may perform safety measures to eliminate the threat of the detected A2L refrigerant leak. Specifically, the HVAC systemmay (step) open the first relay, (step) close the second relay, (step) close the dry contact relay, (step) power on the LED, and (step) power on the buzzer. At step, opening the first relayprevents the 24 volt A/C power that the A2L control boardreceives from the transformerfrom passing to the indoor control board. Removing the 24 volt A/C power from the indoor control boardin turn removes power from the entire HVAC systemsince the blower motor, thermostat, and outdoor unitare all configured to receive 24 volt A/C power, either directly or indirectly, from the indoor control board. Additionally, at step, closing the second relaycauses the 24 volt A/C power that the A2L control boardreceives from the transformerto pass to the blower motordirectly. The 24 volt A/C power run directly to the blower motorcauses the blower motorto run even though the indoor control boardand the thermostathave no power and are turned off. Further, while listed as separate steps, one of ordinary skill would appreciate that in one or more embodiments, either stepor stepmay take place before the other, or in other embodiments, stepand stepmay occur simultaneously. Additionally, one of ordinary skill in the art would appreciate that both stepsandmay be completed within the requisite time after detection of an A2L refrigerant leak as required by A2L safety standards.

At step, in one or more embodiments, the A2L control boardmay close the dry contact relaythat turns on a ventilator. In one or more embodiments, a ventilator may be connected to the HVAC systemby way of first and second ventilator contact pointsandon the A2L control board. Thus, when the A2L sensordetects a leak, the A2L control boardmay close the dry contact relay, which allows power to run directly to the ventilator and turns on the ventilator. Further, at step, when the A2L control boardreceives the A2L refrigerant leak communication, the A2L control boardmay provide power to the LED. Furthermore, at step, when the A2L control boardreceives the A2L refrigerant leak communication, the A2L control boardmay provide power to the buzzer.

Thus, in one or more embodiments, in response to a communication from the A2L sensorthat an A2L refrigerant leak has been detected, the A2L control boardmay turn off the entirety of the HVAC system, except the blower motor, which is powered on, turn on a ventilator if the HVAC systemhas one, and turn on visual and auditory alarms that an A2L refrigerant leak has been detected.

While the methodis described with respect to an HVAC systemincluding a single A2L sensor, one of ordinary skill in the art, would understand that any number of sensors may be used in the system and the method may include electrically coupling the further sensors to the control board, testing the further sensors, and communicating with the further sensors as the further sensors check for A2L refrigerant leaks.

shows a communicating HVAC system using an A2L refrigerant, according to a one or more embodiments. In one or more embodiments, an HVAC systemmay be used to distribute cooled or heated air throughout a buildingto adjust the ambient air temperature insideof the building. The HVAC system may include an indoor unit, an outdoor unit, a thermostat, an A2L control board, an A2L sensor, an outdoor relay, and a high pressure switch.

Generally, in one or more embodiments, the indoor unitmay be fluidly coupled to the outdoor unitsuch that an A2L refrigerant may flow between the indoor unitand the outdoor unitto cool or heat air within the indoor unit. Further, in one or more embodiments, both the indoor unitand the outdoor unitmay be communicatively coupled to each other by way of an RS-485 system communication. The thermostatmay be either a non-communicating or communicating thermostat and may be electrically coupled to the indoor uniteither by a 24 volt A/C connection or an R-485 system communication. Furthermore, in one or more embodiments, the A2L control boardmay be directly electrically coupled to the indoor unitand indirectly electrically coupled to the outdoor unitby way of the outdoor relayand the high pressure switch. The A2L control boardmay act as a passthrough for power to the indoor unitand may be configured to block power from getting to certain parts of the indoor unitif there is an A2L refrigerant leak in the system. Additionally, the A2L control boardmay be configured to turn off the outdoor unit by way of electrical connections between the A2L control board, the outdoor relay, the high pressure switch, and the outdoor unit. Further, the A2L sensormay be physically disposed within the indoor unitand electrically coupled to the A2L control board. The A2L sensormay be configured to send signals to the A2L control boardwhen an A2L refrigerant leak is detected.

In one or more embodiments, indoor unitmay be disposed on the insideof the building. The indoor unitmay be configured to distribute cooled or heated air to rooms on the insideof the building. The indoor unitmay be any type of HVAC system that includes a blowerand a heat exchangerhaving an indoor evaporator coil. Thus, in one or more embodiments, the indoor unitmay be either a furnace or an air handler, as both types of system include, at least, a blower and an indoor evaporator coil. Additionally, the indoor evaporator coilmay be disposed adjacent to the blower, such that when the blowerblows air within the indoor unit, the air is blown through the evaporator coil.

Further, in one or more embodiments, the blowermay include a blower fanand a blower motor. By way of example, in one or more embodiments, the blower motormay be constant torque motor, while in other embodiments, the blower motormay be a permanent split capacitor (PSC) motor. The blower motormay be mechanically coupled to the blower fansuch that when the blower motoris turned on, the blower fanis configured to spin and cause a movement of air out from the blowerand through the indoor evaporator coil. The indoor evaporator coilmay be configured to receive the A2L refrigerant on the inside of the coil while air from the bloweris blown across the outside of the coil, which allows for heat to exchange either from the A2L refrigerant to the air or vice versa. The A2L refrigerant, after cooling or heating the air, may be cycled back to the outdoor unit, where it will go through the reverse heat exchange process before returning to the indoor evaporator coil. Additionally, indoor unitis configured to distribute the air that is blown from the blowerand across the indoor evaporator coilto the rooms on the insideof the buildingby way of the force of the blower.

The indoor unitmay also include a transformerand an indoor control board. The transformermay be directly electrically coupled to and configured to provide 24 volts A/C power to the A2L control board. Further, the indoor control boardmay be electrically coupled to the A2L control boardsuch that the indoor control boardmay receive 24 volts A/C power indirectly from the transformer. Additionally, the indoor control boardmay be electrically coupled to, at least, the blower motorand the thermostat. In one or more embodiments, the transformermay be configured to indirectly provide a 24 volt A/C power to the blower motorby way of the indoor control boardand the A2L control board. In one or more embodiments, the blower motor has its own source of power. So, while the 24 volt A/C power that the blower motor receives does not power on the blower motor, the 24 volt A/C signal is needed to turn the blower motoron. Further, the indoor control boardmay be electrically coupled to the thermostat by either a 24 volt A/C power connection or by an R-485 system communication depending on whether the thermostat is a non-communicating or communicating thermostat, respectively.

Further, the outdoor unitmay be disposed on an outsideof the buildingand be configured to use the outdoor environment to reheat or cool down the A2L refrigerant after it has been run through the indoor evaporator coil. The outdoor unitmay include, but is not limited to, either a heat pump or an air conditioner. Whether the outdoor unitis a heat pump or an air conditioner, the outdoor unitmay include a compressor (not shown), an outdoor coil (not shown), and an outdoor control board. The outdoor unitmay be configured to communicate with the indoor unitthrough RS-485 system communication between the indoor control boardand the outdoor control board. Further, the outdoor control boardmay be electrically coupled to the A2L control boardas discussed below.

Still referring to, in one or more embodiments, the A2L sensormay be configured to detect an A2L refrigerant leak and send a signal reporting as much. In one or more embodiments, the A2L sensormay be configured to detect an A2L refrigerant leak by one of a number of methods, including, at least, by detecting an amount or a concentration of A2L refrigerant in the air that exceeds a leak threshold. The A2L sensormay be electrically coupled to and communicate with the A2L control board. In one or more embodiments, the A2L sensormay be electrically coupled to the A2L control boardby way of a first sensor connector. The A2L sensormay be configured to communicate to the A2L control boardthat the A2L sensoris connected to the system and working properly. Additionally, when the A2L sensordetects an A2L refrigerant leak, it may communicate the A2L refrigerant leak to the A2L control board, which may be configured to receive the signal and perform the safety measures required by A2L safety standards. In one or more embodiments, the A2L sensorand the A2L control boardmay be electrically coupled by way of an RS-485 bus; however, one of ordinary skill in the art would understand that any type of electrical connection that allows the A2L sensorto send a signal to the A2L control boardmay be used.

While the A2L sensoris depicted as being electrically and communicatively coupled to the A2L control boardby way of a wired connection, one of ordinary skill in the art would understand that the A2L sensormay just be communicatively coupled to the A2L control boardwirelessly. In one or more embodiments, the A2L sensormay be communicatively coupled to the A2L control boardby any wireless means, such as Wi-Fi or Bluetooth.

Further, in one or more embodiments, the A2L sensormay be disposed within the indoor unitso that it may detect an A2L refrigerant leak that occurs within the indoor evaporator coilof the HVAC system. As depicted, in one or more embodiments, the A2L sensormay be disposed directly against the indoor evaporator coil to minimize the time it takes for the A2L sensorto detect an A2L refrigerant leak. Further, while the A2L sensoris depicted within the indoor unit, one or ordinary skill in the art would understand that the A2L sensormay instead be disposed within the outdoor unit. Further, while a single sensor is depicted, one of ordinary skill in the art would understand that multiple sensors may be incorporated into the HVAC system to ensure that an A2L refrigerant leak is detected and the required safety measures are taken within the time required by A2L safety standards. For example, one of ordinary skill in the art would understand that the HVAC system may include two A2L sensors, with both A2L sensors disposed within the indoor unit, both A2L sensors disposed within the outdoor unit, or one A2L sensor disposed within each of the indoor unit and the outdoor unit. Thus, one of ordinary skill in the art would understand that in one or more embodiments, a plurality of A2L sensors may be disposed within the HVAC system with one or more A2L sensors disposed within the indoor unit and/or one or more A2L sensors disposed within the outdoor unit as may be determined necessary to ensure that an A2L refrigerant leak is detected and the required safety measures are taken within the time required by A2L safety standards.

Additionally, referring to, in one or more embodiments, the A2L control boardmay be disposed inside of the indoor unit. However, one of ordinary skill in the art would understand that, in one or more embodiments, the A2L control boardmay be disposed outside of the indoor unitand either connected to the indoor unitor adjacent to the indoor unit. Further, in addition to being electrically coupled to the transformer, the indoor control board, and the A2L sensor, as discussed above, the A2L control boardmay be electrically coupled to the outdoor control boardby way of the outdoor relayand the high pressure switch. In one or more embodiments, the outdoor relayand the high pressure switchmay be electrically coupled in series between the A2L control boardand the outdoor control board. In one or more embodiments, the outdoor relaymay be directly electrically coupled to the A2L control boardsuch that the outdoor relayis configured to open upon receiving a 24 volt A/C power signal from the A2L control board. Further, in one or more embodiments, the high pressure switchis electrically coupled to the outdoor control boardsuch that when the high pressure switchopens, the outdoor unitshuts down completely. Furthermore, in one or more embodiments, opening the outdoor relaycauses the high pressure switchto open, which causes the outdoor unitto shut down completely.

In one or more embodiments, the A2L control boardmay include a power supply, a power-in contact point, a first relay, a first power-out contact point, a second relay, a second power-out contact point, a first sensor connector, a second sensor connector, a buzzer, an LED, a dry contact relay, first and second ventilator contact pointsand, and a fuse. The power supplymay be coupled to circuitry on the A2L control boardsuch that the A2L control board may open and close, at least, the first relay, the second relay, and the dry contact relay. Further, in one or more embodiments, the first relaymay be electrically disposed between the power-in contact pointand the first power-out contact point, such that when the first relayis open, power from the power-in contact pointdoes not reach the first power-out contact point. Furthermore, the fusemay be electrically disposed between the power-in contact pointand the first relay. Similarly, in one or more embodiments, the second relaymay be electrically disposed between the power-in contact pointand the second power-out contact point, such that when the second relayis open, power from the power-in contact pointdoes not reach the second power-out contact point. Additionally, the fusemay be electrically disposed between the power-in contact pointand the second relay. By way of example, in one or more embodiments, when the first relayis open, the second relayis closed, and when the second relayis open, the first relayis closed. Further, in one or more embodiments, in the default state, the first relayis open and the second relayis closed.

In one or more embodiments, the transformermay be electrically coupled to the power-in contact point, the first power-out contact pointmay be electrically coupled to the indoor control board, and the second power-out contact pointmay be electrically coupled to outdoor relay.displays a default state of the A2L control board, where the 24 volt A/C power coming from the transformeris routed to the outdoor relay. Further, in one or more embodiments, if the A2L control boardfails, the relays all revert to their default state, and thus, if the A2L control boardfails, power will be directed to the outdoor relay, causing it to open, thus opening the high pressure switchand shutting off the outdoor unit. Furthermore, in one or more embodiments, when the A2L control boardis turned on, the second relayimmediately opens so that power is not unnecessarily run to the outdoor relaybefore necessary. Additionally, after the A2L control boardis turned on, when the system is ready to run, the first relayis closed, turning on the HVAC system.

Further, in one or more embodiments, the power supplymay be coupled to the first sensor connectorand the second sensor connector, separately. Thus, in one or more embodiments, the A2L control boardmay separately test one or more A2L sensorsbefore closing the first relayand powering up the HVAC system. This allows for the A2L control boardto make sure that the sensorsare working properly and there are no A2L refrigerant leaks before beginning the system. While two separate sensor connectors are depicted, one of ordinary skill in the art would understand that the A2L control board may instead include a sensor signal-in contact and a sensor signal-out contact and the one or more sensors may be run in series instead of in parallel.