The present disclosure relates to a device and to a method for detecting filter soiling of a filter system having at least an air filter installed in an air duct and an electrically controlled fan for producing an air flow in the air duct, wherein the device comprises at least a motor controller for controlling the fan motor by means of PWM control and an evaluating apparatus for determining the actual rotational speed (n.sub.i) of the fan in accordance with the actual degree of modulation (T.sub.i) of the motor current for achieving the present rotational speed (n.sub.i), wherein, in the evaluating apparatus, setpoint value pairs (n.sub.setpoint, T.sub.setpoint) for the setpoint rotational speed (n.sub.setpoint) at a certain degree of modulation (T.sub.setpoint) are also stored, as well as a comparator in order to compare the actual value pairs (n.sub.i, T.sub.i) with the setpoint value pairs (n.sub.setpoint, T.sub.setpoint) and to obtain the degree of filter soiling of the air filter therefrom.

A vent hood is configured to receive air from a cooking environment, the vent hood including a filter. A post-filter air quality sensor is configured to provide an air quality signal indicative of sensed air quality parameters of air after exiting the filter. A vent hood controller is configured to indicate an alert that the filter requires servicing, based on a comparison of the sensed air quality parameters to baseline air quality parameters indicating a lack of filter efficiency.

A monitoring system is disclosed for a heating, ventilation, or air conditioning (HVAC) system of a residential or commercial building. The monitoring system includes an evaporator unit device including a first current sensor that measures current supplied to a circulator blower. The measured current from the first current sensor is used to diagnose a problem with the circulator blower. The monitoring system includes a first temperature sensor that measures refrigerant temperature between a condenser and an expansion valve. The monitoring system includes a second temperature sensor that measures refrigerant temperature between an evaporator and a compressor. The monitoring system includes a condenser unit device that communicates with the evaporator unit device. The condenser unit device includes a second current sensor that measures current supplied to the compressor. The evaporator unit device transmits sensor data to a remote monitoring service over a data network.

A monitoring system for a heating, ventilation, or air conditioning (HVAC) system of a residential or commercial building includes an evaporator unit device and four temperature sensors. The evaporator unit device includes an electrical sensor that measures current supplied to a circulator blower of the HVAC system. The measured current from the first electrical sensor is used to diagnose a problem with the circulator blower. The first temperature sensor that measures a temperature of refrigerant flowing between a condenser of the HVAC system and an expansion valve of the HVAC system. The second temperature sensor measures a temperature of refrigerant flowing between an evaporator and a compressor. The third temperature sensor measures a temperature of air flowing away from the evaporator. The fourth temperature sensor measures a temperature of air flowing toward the evaporator. The evaporator unit device transmits sensor data to a remote monitoring service over a data network.

The invention relates to a device (1) and to a method for detecting filter soiling of a filter system consisting of at least an air filter (10) installed in an air duct (20) and an electrically controlled fan (30) for producing an air flow in the air duct (20), wherein the device (1) comprises at least a motor controller (40) for controlling the fan motor (31) by means of PWM control and an evaluating apparatus (50) for determining the actual rotational speed (n.sub.i) of the fan (30) in accordance with the actual degree of modulation (T.sub.i) of the motor current for achieving the present rotational speed (n.sub.i), wherein, in the evaluating apparatus (50), setpoint value pairs (n.sub.setpoint, T.sub.setpoint) for the setpoint rotational speed (n.sub.setpoint) at a certain degree of modulation (T.sub.setpoint) are also stored, as well as a comparator (51) ins order to compare the actual value pairs (n.sub.i, T.sub.i) with the setpoint value pairs (n.sub.setpoint, T.sub.setpoint) and to obtain the degree of filter soiling of the air filter (10) therefrom.

A system and a method that utilizes wet proppants when creating fracturing fluid by receiving wet fracturing sand at a surge tank, vibrating the wet fracturing sand located within the surge tank, liquefying the wet fracturing sand within the surge tank based on the vibration, and metering the liquefied wet fracturing sand from the surge tank to a blending tub.

A system and a method that utilizes wet proppants when creating fracturing fluid by receiving wet fracturing sand at a surge tank, vibrating the wet fracturing sand located within the surge tank, liquefying the wet fracturing sand within the surge tank based on the vibration, and metering the liquefied wet fracturing sand from the surge tank to a blending tub.

A system and a method that utilizes wet proppants when creating fracturing fluid by receiving wet fracturing sand at a surge tank, vibrating the wet fracturing sand located within the surge tank, liquefying the wet fracturing sand within the surge tank based on the vibration, and metering the liquefied wet fracturing sand from the surge tank to a blending tub.

A monitoring system for a heating, ventilation, or air conditioning (HVAC) system of a residential or commercial building includes an evaporator unit device and four temperature sensors. The evaporator unit device includes an electrical sensor that measures current supplied to a circulator blower of the HVAC system. The measured current from the first electrical sensor is used to diagnose a problem with the circulator blower. The first temperature sensor that measures a temperature of refrigerant flowing between a condenser of the HVAC system and an expansion valve of the HVAC system. The second temperature sensor measures a temperature of refrigerant flowing between an evaporator and a compressor. The third temperature sensor measures a temperature of air flowing away from the evaporator. The fourth temperature sensor measures a temperature of air flowing toward the evaporator. The evaporator unit device transmits sensor data to a remote monitoring service over a data network.

A monitoring system is disclosed for a heating, ventilation, or air conditioning (HVAC) system of a residential or commercial building. The monitoring system includes an evaporator unit device including a first current sensor that measures current supplied to a circulator blower. The measured current from the first current sensor is used to diagnose a problem with the circulator blower. The monitoring system includes a first temperature sensor that measures refrigerant temperature between a condenser and an expansion valve. The monitoring system includes a second temperature sensor that measures refrigerant temperature between an evaporator and a compressor. The monitoring system includes a condenser unit device that communicates with the evaporator unit device. The condenser unit device includes a second current sensor that measures current supplied to the compressor. The evaporator unit device transmits sensor data to a remote monitoring service over a data network.