Disclosed herein are related to a system, a method, and a non-transitory computer readable medium for controlling a central plant. In one aspect, the system obtains a control envelope for a device controlled by the controller. The control envelope comprises boundaries of a plurality of control regions in a multidimensional operating space for the device. Each control region is enclosed by a corresponding boundary. The system counts a number of times that a ray of the device crosses the boundary of a control region. The system determines whether an operating point of the device is within the control region based on the counted number. The system operates the device according to a predetermined control technique corresponding to the control region, in response to determining that the operating point of the device is within the control region.

Air conditioner units and methods of operating the same are provided. A method of operating an air conditioner unit includes activating a makeup air system of the air conditioner unit. The makeup air system directs a flow of outside air from the makeup air system to an indoor portion of a housing of the air conditioner unit. The method also includes activating an indoor fan disposed in the indoor portion of the air conditioner unit at a fan speed at least equal to a minimum circulation threshold speed in response to the makeup air system being activated. Activating the indoor fan causes the flow of outside air from the makeup air system to be urged through the indoor portion of the housing. An air conditioner unit may include a controller, and the controller may be configured for performing the method.

A system and method for identifying patterns of indoor air quality sensors. A method includes receiving sensor data from a sensor to determine indoor air quality, the sensor including indoor air quality (IAQ) sensors and identifying a pattern of the sensor data for a period of time. The method may also include comparing current sensor data to the identified pattern of the sensor data and transmitting a message to a user device based at least in part on the comparison to indicate the indoor air quality and the pattern of the sensor data.

An air conditioning system includes a first unit and a second unit. The space above the ceiling of each of a plurality of clean rooms is included in the chamber as a single space common to a plurality of the clean rooms. The first clean room is higher than the second clean room in air cleanliness.

Apparatus for transforming the air exchange load of a higher air exchange rate space into the air exchange load of a lower air exchange rate space, the apparatus including: a housing for mounting to a surface of the higher air exchange rate space; an air inlet formed in the housing; at least one air outlet formed in the housing; a passageway extending through the housing and connecting the air inlet to the at least one air outlet; a circulation fan disposed in the passageway so as to draw the air of the higher air exchange rate space into the air inlet, through the passageway, and return that air to the higher air exchange rate space through the at least one air outlet; and a filter disposed in the passageway for purging noxious substances from the air passing through the passageway.

A humidifier includes a storage water tank configured to accommodate a predetermined amount of water; a circulation water tank having a smaller capacity than the storage water tank and including a circulation low water level sensor; a supply pump configured to supply water from the storage water tank to the circulation water tank; a circulation pump configured to supply water from the circulation water tank to a humidifying member; a residual water tank configured to accommodate water discharged from the circulation water tank; a drainage member disposed between the circulation water tank and the residual water tank selectively to discharge water from the circulation water tank to the residual water tank and a processor configured to control the drainage member to discharge water from the circulation water tank to the residual water tank when a low water level signal is received from the circulation low water level sensor.

A photocatalyst filter is provided. The photocatalyst filter includes: a base in which an internal space is formed. The internal space is permeable to fluid, and a plurality of photocatalyst beads are provided in the internal space, wherein a surface of the internal space is reflective.

An electronic expansion valve includes a valve component and a stator component; the valve component includes a valve body assembly, a valve core, a threaded transmission assembly and a rotor; the valve body assembly is provided with a valve port, and the valve core is driven by the threaded transmission assembly to control an opening of the valve port; a wear-resistant coating is arranged on a contact surface of at least one of components having relative movement of the electronic expansion valve, the wear-resistant coating is applied by spraying, and the wear-resistant coating has a thickness of 5 to 8 microns; and the material of the wear-resistant coating includes a molybdenum disulfide material and a polytetrafluoroethylene material.

A system and method of retrofitting a heating, ventilation, air conditioning, and refrigeration system (HVACR) including one or more brazed, soldered, or mechanical connections between refrigerant lines is disclosed. The method includes removing a refrigerant from the HVACR system. The refrigerant that is removed is a non-flammable refrigerant. An enclosure is installed over the one or more brazed, soldered, or mechanical connections between refrigerant lines. A refrigerant is added to the HVACR system. The refrigerant being added has a global warming potential (GWP) that is relatively lower than the refrigerant removed from the HVACR system. The refrigerant being added has a relatively higher flammability than the refrigerant removed from the HVACR system.

A ventilation system with automatic flow balancing derived from a neural network to consistently achieve a desired flow rate for inlet flow and/or outlet flow in various operating environments to optimize system performance. The system includes a ventilation device that includes an exhaust blower assembly with a blower motor and a control circuit having a mathematical equation that determines an estimated exhaust blower flow based upon select inputs. The ventilation device also includes a supply blower assembly with a blower motor and control circuit having a mathematical equation that determines an estimated supply blower flow based upon select inputs. When the estimated exhaust blower flow is different than an exhaust flow set point, the exhaust control circuit selectively alters power supplied to the exhaust motor. When the estimated supply blower flow is different than a supply flow set point, the supply control circuit selectively alters power supplied to the supply motor.