Abstract: A flexible tubular body with annular ribs defining an expanded heating surface and a pair of integral clamps constitute a heat exchanger that is mountable to a fireplace lintel. Opposite ends of the tubular body, which are exposed at oppposite sides of the fireplace opening, are provided with deflection grates for directing air flow. A panel extends across the fireplace opening at an upper region thereof and constitutes a smoke deflector. A thermostatically controlled, variable speed blower is contained within the tubular body for drawing cool air from the room and for exhausting heated air into the room, the cool air being heated within the tubular body by a fire in the fireplace.