Abstract: A method of operating a HVAC system is provided. The method includes transferring heat between airflow and a heating element in the duct system. The heating element is configured to receive a fuel and ignite the fuel to heat the heating element. The method includes measuring a change in at least one gas property value of the airflow in the duct system using a leak detection sensor, where the change in the at least one gas property value is indicative of a gas leaked into the duct system. The method includes determining a concentration of the leaked gas based at least in part upon the change in the at least one gas property value and determining that the concentration as measured by the leak detection sensor has a negative value, where the negative value is indicative of the leaked gas comprising fuel.

Abstract: The present invention is an improvement to previously known systems for controller area networks and the method of communicating across such networks. The system and method introduces interpolated time markers to provide higher resolution bit container, for communicating data bits across the data bus of a three-wire controller area network. The interpolated time markers allow devices on a controller area network to effectively double tie amount of bandwidth available for communication and can in some cases even further increase the bandwidth beyond a factor of two.

Abstract: The present invention is an improvement to previously known systems for controller area networks and the method of communicating across such networks. The system and method introduces interpolated time markers to provide higher resolution bit container, for communicating data bits across the data bus of a three-wire controller area network. The interpolated time markers allow devices on a controller area network to effectively double tie amount of bandwidth available for communication and can in some cases even further increase the bandwidth beyond a factor of two.

Abstract: Activation and deactivation of a plurality of heating elements in an electric heating system are separately controllable in accordance with the present invention. Individual heating elements are sequentially activated in response to a demand for heat. A predetermined time delay is imposed between successive activations of the heating elements to allow time to satisfy the demand for heat before another heating element is activated. Normally, the heating elements are also deactivated sequentially in response to a reduced demand for heat, with a predetermined time delay between successive deactivations to allow time to respond to the reduced demand for heat before another heating element is deactivated. A temperature sensor is located in the air discharge plenum of the heating system for sensing the temperature of the discharge air. The discharge air temperature is used to control the operation of the heating elements, a two-speed heat pump, and the "off cycle" of the heating system blower.

Abstract: An improved timed-off control apparatus and method are provided to prevent excessive cycling of an electrically operated device, such as an air conditioning compressor. The timed-off control apparatus provides a predetermined timed-off period (e.g., five minutes), during which the electrically operated device is constrained to remain in an off state after the device is deactivated by a loss of power. For example, in an air conditioning system, fluctuations in power supply voltage and thermostat switch bounces may result in excessive cycling of the system compressor. By constraining the compressor to remain deactivated for the selected timed-off period, the compressor is protected against excessive cycling. In order to achieve consistent and predictable timed-off periods, a field effect transistor (FET) is used in conjunction with a resistance/capacitance (RC) circuit. When the power supply is interrupted, the FET is turned off state and remains off during the timed-off period.

Abstract: Automatic food frying and dispensing apparatus is disclosed which is housed in a supporting cabinet and includes a device for holding a supply of cooking oil and a heating device for maintaining the temperature of the cooking oil at a predetermined temperature. A fan assembly exhausts air through the top of the cabinet. A derated precipitator, a flame arrester and a charcoal filter are positioned upstream of the fan assembly and in the path of air flow. A switch device is positioned in the path of air flow and shuts off the heating device if the air flow drops below a predetermined value. Food handling apparatus automatically lowers the food to be cooked into the cooking oil when a customer selects a desired cooking time and automatically raises the food from the cooking oil and dumps the food into a container positioned at the food collection station at the end of the preselected cooking time.