Abstract: A frictional heat generator for fluid used in a circulating heating system. The generator has a closed housing wherein a hollow shaft is driven to rotate perforate rotor discs which are secured in spaced apart relationship along the shaft. A generally cylindrical structure within the housing supports a series of annular perforated stator discs. A fluid heating medium is introduced to the bore of the shaft and passes through suitable openings in the shaft into the restricted housing area where the rotor and stator discs are disposed. Centrifugal force moves the fluid outwardly while it is being violently acted upon by the shearing-like action of the perforate discs. The total movement of the fluid and the action it undergoes generates heat within the fluid, and the fluid flows through appropriate generally radial channels in the cylindrical structure from the restricted area within that structure into the housing chamber around the structure which might be considered a reservoir.