Hvac System with Centralized Control Connected to a Fresh Air Ventilation System

This application claims the priority benefit of U.S. 63/651,929 (filed May 24, 2024), which is incorporated herein by reference in its entirety.

HVAC systems can include a variety of different components that, in order to control the operations of the system, communicate with one another (e.g., via electronic signals), such as thermostats, zone panels, dampers, ventilation controls, sensors, etc. Some systems include components for pulling in fresh air (e.g., outside air) into the system or property, but it can be undesirable to bring in fresh air all of the time or when an air handling unit (AHU) is not running, since the fresh air can be too hot, humid, or cold, leading to excessive electricity costs, discomfort, and indoor air quality issues.

Some systems (e.g., installations of systems) include controls and accessories to reduce the likelihood of fresh air being pulled in when the AHU is not running, but often the HVAC components and controls (e.g., such as in a Variable Refrigerant Volume (VRV) system or a Variable Refrigerant Flow (VRF) system) are equipped to communicate only through proprietary communication means (e.g., encrypted communications). This can make it challenging for HVAC components (e.g., from third parties) that do not communicate via the proprietary communications means to operate in coordination with those systems.

Some acronyms might be used in this description, including (but are not limited to) the below. Unless otherwise described to the contrary, these terms can include meanings as understood in the field of heating, ventilation, and air conditioning (inclusive of cooling, humidity control, and air quality).

The present disclosure is related to a controller for an HVAC system that can receive signals and/or measurements associated with the HVAC system and that can control one or more operations of fresh-air-ventilation (FAV) equipment (e.g., a fresh air fan and/or a fresh air damper). For example, the controller can receive one or more signals from a first sensor indicating whether an air handling unit (AHU) fan is on and one or more signals from a second sensor indicating a quality of the fresh air (e.g., temperature and/or humidity), and based on the signals, the controller can control an operation of the FAV equipment.

In some examples, the controller can control the operations of the FAV equipment without relying on proprietary communication means. That is, the subject matter of the present disclosure can be integrated into an HVAC system (e.g., VRV or VRF system) that includes proprietary communication and can, via one or more non-proprietary communication mechanisms, control when fresh air is introduced into the system (e.g., without communicating/interfacing via the proprietary communication).

In conventional solutions HVAC systems can include some components that communicate with proprietary communication (e.g., VRV and VRF types), such that operations of these systems can often be controlled with only accessories and parts that use the proprietary communication. This limits the availability of equipment and accessories that can work with the system and drives up cost and availability. This can be true in many different types of systems, and especially in multi-family units.

In general “proprietary communication protocol” can include a protocol that might be controlled by a manufacturer (e.g., the manufacturer of a component or system of components) or other entity, and often, the technical details of how to “talk” via the protocol are not widely published or otherwise made available. The technical details that can remain proprietary (or otherwise unknown to third parties thereby making communication more challenging) can include various attributes, features, or characteristics, such as data format and structure; addressing scheme(s); framing and synchronization; and/or encryption. Any one or more of these details can be kept private and not disclosed to third parties.

The present solution includes HVAC system components and accessories that do not use proprietary communication means and that can be used in a variety of different HVAC systems to control operations, including systems (e.g., VRV and VRF) that use proprietary communication means. For example, some HVAC system operations can be configured to bringing fresh air into the system at the appropriate times (e.g., when the AHU is running and/or when the outside air is not too hot, humid, or cold). Bringing outside/fresh air into the system at appropriate or optimized times can reduce the likelihood of excessive electricity costs, discomfort, and indoor air quality issues.

In examples, the system of the present disclosure includes components (e.g., a controller) that can, without relying on proprietary communication protocols or means, provide fresh air when the HVAC system is operating (e.g., when the AHU fan is on) and/or when the outside air includes properties that are conducive to desired states or operating conditions of the system. In some instances, this capability (e.g., to bring in fresh air) can be listed under a building code, such that this solution provides a solution for the engineer/builder/contractor to (without relying on components that only use proprietary communication) meet the ventilation code requirements, even when the system includes proprietary communication equipment (e.g., VRV/VRF equipment).

In at least some examples, the controller of the present solution includes components that detect when the HVAC air handling unit (AHU) is operating (e.g., fan running). In some examples, the present solution includes a component that can determine, via a low voltage signal, when the HVAC AHU is operating. For example, in some instances, the present solution can include an electricity current sensor and/or pressure sensor. In some examples, this can be referred to as an AHU-state sensor, which can be one part of the ventilation controller.

In addition, the system (e.g., the controller) can intelligently determine whether properties or conditions of the outside air are suitable for delivering to the system. For example, the system can include a temperature sensor, a humidity sensor, and/or other sensors to assess properties of the outside air and determine whether the properties/conditions are satisfactory. In some examples, this can include a fresh-air-conditions sensor (e.g., the fresh-air-conditions sensor can be a component of the ventilation controller). The fresh-air-conditions sensor can, in some cases, be positioned in a mixed plenum. In some instances, it can be positioned on the exterior of the building.

In examples, the system of the present disclosure, including the ventilation controller, uses the combination of the AHU-state sensor and the fresh-air-conditions sensor to determine whether to bring in fresh air for delivery to the property.

Referring to, an example systemis illustrated. In examples, the systemincludes some plenum(e.g., mixed plenum) in which fresh air(e.g., unconditioned air from outside or exterior to the building envelope) can be introduced to the system (e.g., via the duct) and then distributed to the home. For example, the systemcan include an air-handling-unit (AHU), which can include an AHU fan with an impeller that rotates via a motor (e.g., ECM) to propel air (e.g., conditioned air) into the conditioned-air space. In some cases, the fresh airis drawn into the AHUand distributed to the space. For example, if the HVAC AHUis in a utility closet, the fresh aircan be delivered into the utility closet (sometimes called a mixed plenum and via the duct), after which the AHUcan deliver the fresh air to the home(conditioned-air space).

In some examples, the AHUcan be a component in a VRV or VRF system, such that the AHU is configured to operate and communicate via proprietary communications. For example, the systemcan include a controller(e.g., a first controller) that exchanges communications with the AHUvia a proprietary communication protocol. In some instances, the controllercan include a thermostat or other type of control system.

In some examples of the present disclosure, the system can include a fan powered product(e.g., FAPV) to actively bring fresh airfrom outside into the plenum. In addition, or alternatively, the systemcan include a ductfrom the plenumto the outside that is controlled via a damper(e.g., FAD).

In examples, the systemincludes a controller(e.g., second controller or ventilation controller) that can control operations related to ventilation, such as by bringing fresh air into the system. For example, the controllercan, based on the state of the AHUand/or the conditions of the outside air, control operations associated with the FAPVand/or FAD.

includes an example of a printed circuit board (PCB)of a controller, based on an example of this disclosure. In at least some examples, the controllercan include (or otherwise be in communication with) a temperature sensor, a humidity sensor, and/or other sensors (e.g., sensor). For example, one or more of these sensors can be mounted to the PCB(e.g., could be mounted directly to the PCB, such as in the lower right corner at component), such that the sensors are positioned in the mixed plenum(e.g., where the controlleris mounted). In some examples, these sensors can be externally mounted (e.g., external to the controller) and can communicate with the controller(e.g., with the components of the PCB) via a wired or wireless connection. In examples, the sensor(s) can provide signals and data to the controller that represents conditions or properties (e.g., temperature, humidity, etc.) associated with the outside airand/or the properties of the mixed air in the mixed plenum. The PCBcan also include connectorsfor connection (e.g., wired connection) to one or more other components, such as the FAV equipment, DAT sensor, and AHU-state sensor.

In at least some examples, the systemcan include a component that does not rely on proprietary communications and that can determine when the AHU fanis on (e.g., the component can detect a condition that indicates or suggests the AHU fan is running). That is, even though the AHUcan be a component of a system that uses proprietary communication (e.g., a VRF or VRV system), the systemcan still determine when the AHU fanis likely running and can use that status information to optimize control and operations of other components (e.g., the FAV components). Based on the determination, fresh aircan be pulled into the system (e.g., via the fan powered productand/or the dampered duct).

In some examples, the component (AHU-state sensor) for determining when the AHU fanis lily on includes provisions for a low voltage signal to be used with a current sensing switch or a pressure sensing switch to indicate when the motor of the AHU fan is operating (e.g., ECM).

Referring to, a schematic of a systemis depicted, and the systemcan be a part or subsystem within the system. For example, the systemcan include connections(e.g., connectors) that are associated with the controller(e.g., the connectionscan correspond with the connectorson the PCB). In at least one example, the AHU-state sensorincludes a current-sensing switch (e.g., C-sensor) that connects to the controller, such as via a wired connection into the connections. In addition, the controllercan be connected (e.g., via the connections) to the ventilation fan(e.g., FAPV fan) that draws in outside air, and this could also/alternatively include a damper (e.g., FAD).

In, the state sensorcan (e.g., via the current sensing switch) isolate activation of the switch due to idle currents common with motors of AHU fans (e.g. ECM-type motors). In examples, this current sensing switch could be installed onto the mains line feed or on the motor lead supplying power to the motor unit. In examples, the current sensing switch can be adjustable to compensate for idle current within the system to reduce the likelihood of false triggering of the ventilation controller. In examples, when the central fan (e.g. AHU fan) becomes active (e.g., such as by the controlling thermostat), the sensing switch will close its contacts to complete a low voltage circuit within the controller(e.g., via the connections) to indicate the fanmight be operating. In other words, the sensorcan detect a condition (e.g., current) and send a signal (e.g., data) to the controller. When the central fanstops activity and power is no longer supplied, the circuit of the sensorwill become open, which can be interpreted by the controlleras a signal from the sensorthat the AHU fan might not be running. In at least some examples, this solution provides a mechanism to determine when the AHU fan(e.g., the fan of the AHU) is likely on without having to rely on proprietary communication associated with the system(e.g., such as when the AHU is part of a VRV or VRF system).

Referring to, a schematic of a systemis depicted, and the systemcan be a part or subsystem within the system. For example, the systemcan include connectionsthat are associated with the controller(e.g., the connectionscan correspond with the connectorson the PCB). In at least one example, the AHU-state sensorincludes a pressure switch that connects to the controller, such as via a wired connection into the connections. In addition, the controllercan be connected (e.g., via the connections) to the ventilation fan(e.g., FAPV fan) that draws in outside air, and this could also/alternatively include a damper (e.g., FAD).

In examples, the sensormight be a less invasive installation, as compared to the current sensing switch of the sensor. For example, an adjustable pressure switch could be easier to install in the ductwork before and/or after the AHU fan (e.g., easier as compared to the sensorin which it might be necessary to break a mains circuit or fitting the device in the non-class II area of the AHU). In examples, the pressure sensing switch of the AHU-state sensorcan be adjustable to cover a wide range of static pressures starting as low as 0.08 in. WC up to 1.2 in. WC. In examples, the pressure switch contacts are made (e.g., to complete the circuit) when the pressure changes beyond some threshold (e.g., pressure increases above a threshold). In response, a signal (e.g., data) can be provided to the controllerto indicate the AHU fanis likely running. In addition, when the pressure falls below the threshold, the circuit is broken, which can similarly be interpreted as a signal (e.g., data) by the controllerthat the AHU fan may not be running. In at least some examples, this solution provides a mechanism to determine when the AHU fan(e.g., similar to the fan of the AHU) is likely on without having to rely on proprietary communication associated with the system.

In some examples, the systemcan include the systemand the system, which can provide redundancy related to determining a state of the AHU without relying on proprietary communications. In some examples, the systemcan include the systemwithout the system(e.g., without the current sensor). In some examples, the systemcan include the systemwithout the system(e.g., without the pressure sensor)

In at least some examples, and consistent with, the discharge-air-temperature (DAT) sensororcan be used to determine (e.g., by inference) whether the thermostat is calling for cooling or heating (e.g., due to temperature change monitored by the sensoror). In this respect the DAT sensororcan be used determine if the systemis in heating (e.g., the air temperature measured is increasing by at least a threshold amount), cooling (e.g., the air temperature measured is decreasing by at least a threshold amount), or the thermostat is operating the fan for circulation purposes only (e.g., the air temperature is not changing by more than a threshold amount).

The controller(e.g., ventilation controller) can be programmed to execute various protocols. In at least one example, for some initial threshold duration of activity from the ECM motor (e.g., first 45 seconds), the ventilation controllercan measure the return air temperature and humidity (e.g., via one or more sensors in the return air supply duct) to get a baseline of the interior conditions (e.g., inside the home). After the initial threshold duration of central fan activity, the ventilation controllercan turn on the FAPV-Land/or FADand allow for a grace period (e.g., 45 seconds) of which, the ventilation controllercan determine whether the fresh air ventilation should continue (e.g., based on whether outside airhumidity and temperature are suitable for ventilation, such as using the sensors connected via) or whether the ventilation should be terminated (e.g., outside air is too humid, too hot or too cold to continue ventilation). If the fresh airfrom the outside is unsuitable for ventilation, the ventilation controllercan place a hold on fresh air ventilation and wait for a change in the DAT sensorortemperature. A drop in temperature (as measured via the DAT sensoror) can indicate the systemis in cooling mode and a rise in temperature (as measured via the DAT sensoror) can indicate the systemis in heating.

If the ventilation controllerhas aborted a fresh air ventilation due to temperature or humidity, the ventilation controllercan be in waiting mode for heating or cooling to become active in order to continue with the fresh air ventilation activity. If the measured humidity levels are on a rise due to fresh air ventilation (e.g., based on receiving data from the sensors connected to), the ventilation controllercan terminate the call for ventilation and wait until humidity levels monitored in the mixed plenumhave dropped to suitable levels before continuing the ventilation activity.

In examples, the controllercan, based on one or more various settings, optimize the delivery of fresh air to the system (e.g., after the controllerhas determined that one or more pre-conditions are met for the delivery of fresh air, such as the AHU fanbeing on and/or the outside fresh air being associated with suitable conditions).

In some instances, the controllercan adjust the fresh air activity time (e.g., operating time of the FAV fanor opening time of the damper) due to increase or decrease in mixed plenumrelative humidity (e.g., based on data from the sensors).

In some examples, the controllercan adjust the fresh air activity time (e.g., operating time of the FAV fanor opening time of the damper) due to increase or decrease in mixed plenumtemperature (e.g., based on data from the sensors).

In some examples, the controllercan adjust the fresh air flow rate (e.g., by adjusting a fresh-air damper position to be more open or closed and/or by adjusting FAV fan motor speeds/operation) due to increase or decrease in mixed plenum relative humidity.

In some examples, the controllercan adjust the fresh air flow rate due to increase or decrease in mixed plenum temperature.

In some examples, the controllercan dynamically control fresh air ventilation across a wide activity range (e.g., 0% to 150% of the fresh air ventilation activity) based on the air conditions. For example, fresh-air ventilation activity could be reduced to some level greater than 0% (e.g., to 25%) when conditions do not result in saturated humidity levels but are not quite favorable to sustain a longer running time. In at least some examples, during periods of good to prime environmental conditions (e.g., associate with the fresh air conditions), the FAV activity can be increased up to 150%. In doing this over a 24 hour period, this can compensate for periods of activity that were less suitable for ventilation.

As used herein, a recitation of “and/or” with respect to two or more elements should be interpreted to mean only one element, or a combination of elements. For example, “element A, element B, and/or element C” may include only element A, only element B, only element C, element A and element B, element A and element C, element B and element C, or elements A, B, and C. In addition, “at least one of element A or element B” may include at least one of element A, at least one of element B, or at least one of element A and at least one of element B. Further, “at least one of element A and element B” may include at least one of element A, at least one of element B, or at least one of element A and at least one of element B.

This detailed description is provided in order to meet statutory requirements. However, this description is not intended to limit the scope of the invention described herein. Rather, the claimed subject matter may be embodied in different ways, to include different steps, different combinations of steps, different elements, and/or different combinations of elements, similar or equivalent to those described in this disclosure, and in conjunction with other present or future technologies. The examples herein are intended in all respects to be illustrative rather than restrictive. In this sense, alternative examples or implementations can become apparent to those of ordinary skill in the art to which the present subject matter pertains without departing from the scope hereof.