PURPOSE: To attain a saving of fuel and comfortable cooling and heating by a method wherein a hot-water boiler is controlled so that the temperature of hot-water flowing into a cistern falls by a specified value until restarting-up of a fan after it is once stopped.

CONSTITUTION: An indoor-side controller 7 restarts a fan 4 when hot-water temperatures detected by a hot-water temperature sensor 6 reach a specified value, and sends hot-air into a room. When the temperature inside the room detected by a temperature sensor 5 exceeds a set point, the fan 4 is stopped, and when the temperature inside the room drops to a specified value or lower, the fan 4 is restarted. The information on stoppage and restart-up of the fan 4 is transmitted to an outdoor-side controller 12. The outdoor-side controller 12 controls a hot-water boiler 8 so that hot-water is kept at 85°C, for example, while the fan 4 is in operation and at 65°C while the fan 4 is in stoppage state. Thereby, fuel can be saved and the comfort can be improved as the temperature of supply air gently rises when the fan 4 is restarted.