A problem to be solved by the present disclosure is to enhance the reliability of determination of occurrence or non-occurrence of surging. Whether or not surging occurs depends on front-rear differential pressure. Therefore, by determining occurrence or non-occurrence of surging on the basis of the front-rear differential pressure, a second unit can detect and avoid surging with higher accuracy than when determining by using the pressure on an outlet side of a second fan.

A fan unit reduces the number of man-hours for a preliminary test and eliminates the need for a trial run at the time of duct connection are realized. A second controller acquires: a rotation speed of a fan motor of a second fan; a volume of air, a wind speed, or front-rear differential pressure of the second fan; and an air volume target value or a wind speed target value for the second fan, and calculates a rotation speed target value Ny for the fan motor 31b by using a first function: Ny=(Qy/Qx).sup.2×ΔPx×{m×(Qy/Qx)×Vx+p}+n×(Qy/Qx)×Vx+q. Furthermore, when the front-rear differential pressure fluctuates and the wind speed is decreased from Vt to V, the second controller calculates a rotation speed change amount to the rotation speed target value by using a second function: ΔN=a×(Vt−V).

An air conditioner having six ports is described. The inner space of a casing having six inlet/outlets including a first discharge port, a second discharge port, a first outdoor air intake port, a second outdoor air intake port, and an interior air suction port is divided by a partition wall to form a first passage and a second passage. A waste heat recovery heat exchanger is provided between the first passage and the second passage. The air flow direction and the air volume can be controlled by using a direction change damper, a first air volume control damper, and a second air volume control damper.

Methods, systems, and devices for humidifying are described herein. One method includes determining a temperature in a space associated with a humidifying unit, determining a relative humidity in the space, determining an air speed associated with the humidifying unit, and adjusting an amount of water sprayed by the humidifying unit based, at least in part, on the temperature, the relative humidity, and the air speed.

Controlling a switching element in accordance with a voltage output from a signal amplifying circuit enables adjusting a voltage to be received by a current calculation circuit. Even when a range of a air volume to be used is wide and a range of output of a DC motor is wide, or a current flowing through the DC motor has a wide range, a resistance value of a shunt resistor and an amplification factor of a signal amplifying circuit are not required to be reduced, and thus current detection accuracy of the DC motor can be improved.

Methods and systems to measure a volumetric fluid flow rate through a fluid flow passage, such as an air handler of a HVAC system, are described. The method may include obtaining a flow rate measurement in a measuring section, and calculating a total flow rate based on a correlation between the obtained flow rate measurement and the total flow rate. The method may also include blocking a portion of the fluid flow passage so that when a minimal volumetric fluid flow rate is provided, the flow rate measurement obtained in the measuring section is at about a minimal sensitivity flow rate requirement.

A device for generating ultraviolet (UV) radiation whose wavelength is optimally tuned into the range of 250 to 285 nm, with peak wavelength in the range of 260 to 270 nm, which attains a Peak Germicidal Disinfection Effectiveness Index of nearly 100%, superior to conventional UV lights and lamps. The device comprises an ultraviolet light-emitting diode (LED) array, an operation control system, an airflow sensor with programmable sensitivity, and a surge protection module. The device is installed in conventional HVAC systems such as air conditioning systems and HVAC ducts to effectively disinfect airflow passing through to deactivate bacteria, viruses, and mold. Depending on the operating status of the HVAC systems, the device senses airflow passing through or going around and intelligently turns on and off the ultraviolet LED array to attain a longer lifetime.

Dual inlet air diffuser for a heating ventilation and air conditioning (HVAC) system. The dual inlet air diffuser mixes two or more separate and/or distinct air streams into a homogenous or nearly homogenous mixture of air. The two or more separate air streams may have different temperatures and/or different humidity levels, and/or may be from different sources, such as having one air stream comprising ventilation air that includes filtered air from an outside, ambient air source and a second conditioned air stream from a heating, air conditioning, or other air treatment unit.

An air pressure measuring ventilation system, comprising: at least one duct; at least one motorized exhaust fan; and one or more air pressure sensors. The at least one motorized exhaust fan may draw air through the at least one duct. The one or more air pressure sensors may be placed on a side of the at least one duct such that an air pressure is measured as the air is drawn through the at least one duct, such that a plurality of air pressure measurements are generated. The one or more air pressure sensors may be substantially flush with an interior side of the at least one duct and do not obstruct the air as the air is drawn through the at least one duct.

An integrated device in an HVAC system is configured to modify an environmental condition of a building. The device includes a valve configured to regulate the flow of fluid through a conduit, an actuator comprising a motor and a drive device, and a communications mechanism. The communications mechanism is configured to receive a flow rate setpoint from an external control device of an outer control loop. The device further includes a processing circuit. The processing circuit is configured to determine an actuator position setpoint using a cascaded feedback control mechanism based on the flow rate setpoint and a flow rate measurement from a flow rate sensor of an inner control loop. The valve, the actuator, the communications mechanism, and the processing circuit are located within a common integrated device chassis.