PURPOSE: To uniform temperature distribution by a method wherein a heat medium, flowing through the copper tube of a floor heating panel, is flowed in the shape of two-phase flow in either case of using convection-type radiator and the floor heating panel simultaneously or using only the floor heating panel.

CONSTITUTION: The convection-type radiator 1, the floor heating panel 4, a refrigerant circulating liquid pump 6 and a refrigerant heating evaporator 8 are connected annularly and sequentially to constitute a heat moving circuit and the circuit is filled with Flon series refrigerant while the discharging pipe and suction pipe of the pump 6 are connected by a bypass pipe 13 interposed with an opening and closing valve 14. Thus, the refrigerant, flowing through the copper pipe of the panel 4, flows in the shape of two-phase in either case of using the radiator 1 and the panel 4 simultaneously or using the panel 4 only. The temperature of the refrigerant is constant in the two-phase area and an uniform temperature distribution may be obtained on the whole surface of the panel 4 while the ununiformity of the floor temperature distribution, seen in conventional hot-water systems, is eliminated and room heating effect may be increased.