A high efficiency grate and stove heating unit for extracting useful heat from a fire, comprising in combination a low metal enclosure having an expansive top wall constituting a grate proper for supporting fireplace logs and the coals resulting therefrom, together with multiple heat exchangers in the form of plates or corrugation ribs on the top wall and means to cradle the logs thereof. Other plates or corrugation ribs extend downward from the top wall, and the plates can abut the bottom enclosure wall to constitute a reinforcement means. In one embodiment of the invention the enclosure includes an air inlet port connected with an electric blower for forcing air into the enclosure, together with multiple outlet ports from which the air, now heated, flows. A series of forward protruding nozzles is carried by the enclosure and communicates with the outlet ports to channel the heated air in directions away from the enclosure and its inlet port. Disposed between the blower and the fire area is a heat shield that intercepts radiant heat from the fire, which would otherwise impinge on the blower and cause over-heating of the same. The ribs or plates extending downward from the top wall of the grate form of enclosure constitute a series of internal compartments, and force the circulating air to follow tortuous or circuitous paths. In a preferred embodiment of the invention, the blower simultaneously pressurizes all the compartments, with each of the latter in turn communicating with one of the enclosure's outlet ports.