A fireplace heat exchanger grate comprising an inlet manifold, an outlet manifold and a plurality of heat exchanger tubes or pipes providing communication between the inlet and outlet manifolds. First and second duct sections are in open communication respectively with the inlet and outlet manifolds. A low-profile connector duct section extends across the front of the fireplace in open communication with both the first and second duct sections. The connector duct section includes an internal baffle between its connections to the first and second duct sections. A blower is connected to a first end of the connector duct section. Flow from the blower is directed by the baffle into the first duct section, through the inlet manifold, the heat exchanger tubes and the outlet manifold to the second duct section and outwardly through exhaust vents in the connector duct section on the downstream side of the internal baffle. The connections between the inlet manifold and the first duct section and between the outlet manifold and second duct section are telescopic to permit the heat exchanger to be adjusted to accommodate varying depths of fireplaces. The first and second duct sections are removably attached to the connector duct section so that the connector duct section can be positioned in either of two relative orientations in front of the fireplace and the blower is designed to permit it to be positioned in either of two relative orientations.