Abstract: A heat exchanger for heating rooms with heat from a dryer comprising a container in a generally rectangular configuration with a centrally located heating chamber therewithin; a first air-inlet opening and a first air-outlet opening in axial alignment defining a first airflow path through the container for the passage of air from the atmosphere in a room for being heated and for discharging the heated air to the room; a dryer air-inlet and a dryer air-outlet in axial alignment defining a second airflow path through the container generally perpendicular to the first airflow path; a fan in the first air-inlet opening of the first airflow path prior to the chamber to effect the flow of air from a room through the chamber and to exterior thereof; and means within the chamber for directing the flow of air from the dryer whereby hot air from the dryer passing through the chamber will pass therethrough to preclude such dryer air and any contaminants from coming into direct contact with air flowing along the second a