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.

The aim is to create a facility which is carried out without operator intervention, operates without delay, does not require a connection to the mains and meets the requirements of the regulations on permissible pollutant emissions. The device consists of a control unit which is electrically connected to two temperature sensors and a door contact switch and actuates an actuator via an electric motor and transmission elements. The temperature detection in the flue takes place behind the outlet of the respective combustion chamber. The temperature sensors record the temperature change over time and the speed of the temperature change. The temperature target-actual evaluation serves to record the burning state of the solid fuel. The degree of the outgassing process is carried out by recording and evaluating the temperature rise or temperature drop over time. The target-actual temperature over time in comparison with comparative values for combustion optimization is carried out as an adaptive system. Thus, the respective nature of the solid fuel for the optimal combustion process is taken into account and the necessity of the new feed with solid fuel is determined via the program and displayed via a visual signaling device. The device is used for electronic control for a fireplace with lower burn. The invention relates to a device that does not require operator intervention, operates without delay, does not require a mains connection, and meets the requirements of the regulations with respect to permissible pollutant emissions. The device consists of a control unit which is electrically connected to two temperature sensors and to a door contact switch and which actuates an actuator by means of an electric motor and transmission elements. The temperature is detected in the flue behind the outlet of the combustion chamber. The temperature sensors record the change in temperature over time and the speed of the change in temperature. The temperature target/actual evaluation is used to record the combustion state of the solid fuel. The degree of the outgassing process is determined by recording and evaluating the increase or decrease in temperature over time. The target/actual temperature over time compared to comparative values for optimising combustion is an adaptive system. Therefore, the composition of the solid fuel is taken into account for the optimum combustion process and the necessity of the new charging with solid fuel is determined by means of the programme and displayed by means of an optical signal transmitter. The device is used for electronic closed-loop control for a fireplace comprising a lower combustion system.

A wood burning sauna stove includes an outer frame and a firebox inside the outer frame. The outer frame includes an upper frame wall, a front frame wall, a rear frame wall, and lateral frame walls connecting the front frame wall and the rear frame wall. The upper frame wall is designed to support sauna rocks. The firebox includes an upper firebox wall, a lower firebox wall, and a perimeter firebox wall. The perimeter firebox wall includes front, rear, and side firebox walls. An exhaust conduit is positioned between the upper frame wall and the upper firebox wall to heat the upper frame wall and the sauna rocks on the upper frame wall. The exhaust conduit has an exhaust inlet aperture in the upper firebox wall adjacent the front firebox wall and an exhaust outlet aperture in the upper frame wall adjacent the rear firebox wall.