A heater is adapted to provide heat for heating a room by effecting heat exchange in a heat section which is between combustion and ventilation sections. The heat exchange section comprises a rotary body positioned across the combustion and ventilation sections so as to rotate at that position. The rotary body has air flow passages extending in the same direction as the axis of rotation of the rotary body. The heater can effect heat exchange with an increased efficiency and also can prevent the interior of the room from being abnormally dried.
