A method and apparatus for controlling a combustion heater are provided. An example method includes measuring a room temperature, measuring a combustion heater temperature, and measuring a fuel weight. Adjustments are computed to an operational parameter to adjust a room temperature. An anticipatory alert is provided to inform a user of a predicted time at which the fuel weight will be too low to maintain the room temperature

A safety switch that prevents the flow of gas in a gas operated fireplace or furnace when a damper is in a closed position, and only allows the gas flow when the damper is in an open position. The safety switch is mechanically connected to the damper and electrically connected to a gas line valve. When the damper is in an open position, the safety switch allows the gas to flow, or conversely, when the damper is in a closed position, the safety switch prevents the gas from flowing. The safety switch also may provide for audio or visual alerts to indicate the open or closed status of the damper.

The present invention may be embodied as a biofuel heating system comprising a controller for operating a fan based on a load operating parameter such that air flows along a flow path extending through a combustion chamber, through a burn-out port, through a burn-out chamber, through a heat exchange port, through a heat exchange chamber, and out of an exhaust port. A heat exchange system transfers heat energy from air flowing through the heat exchange chamber to a working fluid. The controller operates in a char mode based at least in part on the load operating parameter, and the biofuel remains within the combustion zone during the char mode.

A fuel fired, atmospheric water heater has a burner positioned inside a combustion chamber. All combustion air entering the combustion chamber must pass through a damper. The damper is operable to adjust the flow resistance to combustion air entering the combustion chamber. The damper is biased to a closed position such that during non-firing periods of the water heater, the damper significantly reduces the flow rate of combustion air being provided to the combustion chamber reducing standby heat loss. An actuator is in fluid communication with a fuel supply line such that when pressurized fuel is provided to the burner, the pressurized fuel causes the actuator to move the damper to an open position to permit operative combustion air delivery to the combustion chamber during firing periods of the water heater.

A controller for use in a gas appliance system includes a circuit board, a plurality of connectors and a processor mounted on the circuit board. The processor controls operation of the gas appliance using, in part, at least one connector of the plurality of connectors and control settings for an intermittent pilot (IP) system in response to a user selection to configure the controller to control an IP system, and controls operation of the gas appliance using, in part, at least one connector of the plurality of connectors and control settings for a direct spark ignition (DSI) system in response to a user selection to configure the controller to control a DSI system.

Combustion systems configured to achieve, and methods of operating combustion systems to attain, enhanced high turndown operation, are disclosed herein. In one example embodiment, a combustion system includes an air flow tube, an air inlet damper, a gas train, a mixing chamber, a burner, and a blower. A flow of air via the tube into the mixing chamber is governed at least in part by a status of the air inlet damper. Further, the air inlet damper includes a damper plate having an outer perimeter with a first edge portion that is complementary to an inner surface of the tube and one or more additional edge portions that define a first inwardly-extending cutout. In another example embodiment, the combustion system includes a control device configured to cause a control signal for receipt by the damper motor to vary nonlinearly in response to variation of a modulation signal.

Combustion systems configured to achieve, and methods of operating combustion systems to attain, enhanced high turndown operation, are disclosed herein. In one example embodiment, a combustion system includes an air flow tube, an air inlet damper, a gas train, a mixing chamber, a burner, and a blower. A flow of air via the tube into the mixing chamber is governed at least in part by a status of the air inlet damper. Further, the air inlet damper includes a damper plate having an outer perimeter with a first edge portion that is complementary to an inner surface of the tube and one or more additional edge portions that define a first inwardly-extending cutout. In another example embodiment, the combustion system includes a control device configured to cause a control signal for receipt by the damper motor to vary nonlinearly in response to variation of a modulation signal.

In a hot water supply apparatus including a heat exchanger to which water heated by renewable energy or waste heat from other heat sources is supplied, a controller performs an intermittent combustion control in which combustion and combustion stoppage in a burner are repeated as a condition in which a water supply temperature exceeds a predetermined upper limit of the water supply temperature. In the intermittent combustion control, a combustion fan is caused to operate during the combustion and to at least temporarily, preferably always, operate during the combustion stoppage.

In a hot water supply apparatus including a heat exchanger to which water heated by renewable energy or waste heat from other heat sources is supplied, a controller performs an intermittent combustion control in which combustion and combustion stoppage in a burner are repeated as a condition in which a water supply temperature exceeds a predetermined upper limit of the water supply temperature. In the intermittent combustion control, a combustion fan is caused to operate during the combustion and to at least temporarily, preferably always, operate during the combustion stoppage.