Abstract: A system and method for monitoring and controlling an energy demand by an HVAC system utilizes a control device that is operably installed in the HVAC system. The system performs the following steps: receiving, in a control device, values of one or more parameters related to performance of the plurality of powered components; comparing the received values with corresponding predetermined threshold values; determining overloading of the electrical grid by a powered component based on respective values of one or more parameters being less than the corresponding predetermined threshold values for the powered component; and selectively controlling the operation of the powered component without disrupting operation of the remaining plurality of powered components.

Abstract: A filter condition sensing circuit includes current and voltage sensors and a data processor. The current and voltage sensors produce signals indicating magnitudes of electrical current and voltage, respectively, provided to an electric motor used to move a fluid (a gas or liquid) through a filter element. During a first time period, the data processor uses the signals to determine an acceptable range of electrical power required by the motor. During a second time period, the data processor uses the signals to determine a magnitude of electrical power required by the motor. When the magnitude of electrical power is within the acceptable range of electrical power, the data processor generates a signal indicating a normal condition of the filter element. A described filter condition indicating system includes the circuit. A method is for determining a condition of a filter element.

Abstract: A filter condition sensing circuit is disclosed including current and voltage sensors and a data processor. The current and voltage sensors produce. signals indicating magnitudes of electrical current and voltage, respectively, provided to an electric motor used to move a fluid (a gas or liquid) through a filter element. During a first time period, the data processor uses the signals to determine an acceptable range of electrical power required by the motor. During a second time period, the data processor uses the signals to determine a magnitude of electrical power required by the motor. When the magnitude of electrical power is within the acceptable range of electrical power, the data processor generates a signal indicating a normal condition of the filter element. A described filter condition indicating system includes the circuit. A method is disclosed for determining a condition of a filter element.