An example heat recovery apparatus includes a chimney configured to exhaust air and smoke from a biochar kiln combustion chamber. The example heat recovery apparatus also includes a heat exchanger configured to recover heat from the chimney and provide the heat to a secondary application.

In a suction fan type combustion apparatus, when an air supply/exhaust path of a combustion and heating unit is clogged, a combustion fan has a degraded fan current for the same fan rotation speed. Furthermore, the suction fan type configuration has the combustion and heating unit's internal pressure reduced as the combustion fan rotates faster. A combustion burner supplies fuel gas with a pressure applied thereto, which is regulated by a gas proportional valve. A degree of opening of the gas proportional valve is corrected in a direction allowing the pressure to be reduced, in accordance with a rate of degradation of a fan current relative to a reference current following a reference current characteristic. This control for correction is done with the fan current degradation rate smoothed (or low-pass filtered) in a time base direction.

A controlled kiln and manufacturing system for biochar production includes control systems and subsystems. An example biochar kiln exhaust apparatus, includes a chimney configured for heating by pyrolysis and for exhausting smoke from the combustion chamber. The example biochar kiln exhaust apparatus also includes a plurality of exhaust inlet pipes configured to pass smoke from the combustion chamber to the chimney.

A controller for a gas furnace, a computer-usable medium for implementing a method and a gas furnace are disclosed herein. In one embodiment, the controller includes: (1) an interface configured to receive a heating call and (2) a processor configured to enable an inducer of the gas furnace at a low speed based on the heating call and ignite the gas furnace at a high fire operation when determining a low fire pressure switch of the gas furnace is open.

A modulating burner apparatus includes a burner and a blower placed upstream of the burner. A venturi is placed upstream of the blower. A damper valve is placed upstream of the venturi. The damper valve has an open position and a restricted position. A smaller gas valve and a larger gas valve are communicated with the venturi. A controller is operably associated with the system to select a position of the damper valve and to select the appropriate one of the gas valves so as to provide a low output operation mode and a high output operation mode, which in combination provide an overall turndown ratio of at least 25:1.

A controlled kiln and manufacturing system for biochar production includes control systems and subsystems. An example controlled kiln (100) includes a drum (200), a lid (120) and a floor (250) together forming a combustion chamber configured to contain feedstock for conversion into biochar. A catalytic converter (700) may be operatively coupled with an outlet of the kiln (100). A monitor and control subsystem may be operative to issue notifications or automatically end biochar conversion. A ventilation and exhaust system including independently controllable air inlet ports (240), a chimney (300) and smoke inlet pipes (330) enables regulation of smoke flow from a combustion chamber of the kiln while a heat exchanger (1000) enables providing exhaust heat to one or more secondary applications.

A furnace assembly comprising a non-condensing furnace with a draft inducer. The draft inducer includes a permanent magnet electrically commutated motor and a draft inducer blower fan. The motor includes a stator, a rotor, a motor cooling fan, and a controller. The rotor being rotatable relative to the stator, the fan being operatively coupled to the rotor such that rotation of the rotor causes rotation of the fan, the controller being configured to selectively operate the motor in first and second different torque ranges of the rotor, with the first and second torque range operating within a fixed percentage and within a fixed percentage of each other. The controller being configured such during normal operation, the motor is not operable at any torques between the first torque range and the second torque range except during transitionary periods.

A furnace assembly comprising a non-condensing furnace with a draft inducer. The draft inducer includes a permanent magnet electrically commutated motor and a draft inducer blower fan. The motor includes a stator, a rotor, a motor cooling fan, and a controller. The rotor being rotatable relative to the stator, the fan being operatively coupled to the rotor such that rotation of the rotor causes rotation of the fan, the controller being configured to selectively operate the motor in first and second different torque ranges of the rotor, with the first and second torque range operating within a fixed percentage and within a fixed percentage of each other. The controller being configured such during normal operation, the motor is not operable at any torques between the first torque range and the second torque range except during transitionary periods.

A controller monitors oxygen levels in a bio-fuel fired device and automatically controls dampers, blowers and the like to reduce generation of smoke or other pollutants, thereby promoting proper operation of a catalytic converter.

A motor controller for a draft inducer motor that operates an inducer blower in a furnace is provided. The motor controller includes a communication interface operable to receive a signal from a system controller. The signal represents a command to operate the draft inducer motor. The motor controller includes a processor operable to operate the draft inducer motor in accordance with a predefined motor speed profile during at least one of an ignition stage and a combustion stage of the furnace.