Abstract: A friction heat generator is shown for use as the heat source of a furnace heating system. This heat generator has an oil-filled, cylindrical housing supporting a longitudinal auger in close-fitting, running relationship. The housing is substantially filled with oil, and an external motor is joined to the shaft of the auger for driving the auger at a high speed for moving the oil towards one end of the housing. An auxiliary pump is located adjacent that one end of the housing, and it is provided with a discharge port for carrying off the heated oil from the housing at an increased volumetric capacity. Cooperating with the friction heat generator is a heat exchanger that is joined to the generator by conduits to form a closed, recycling heating system. Several modifications of auxiliary pumps are provided in the form of a rotary impeller, as well as one including a plurality of piston pumps acting off a rotary cam.