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.