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The genuine OEM Lennox 99M79 heat exchanger assembly (factory reference R48077004) is the primary heat-transfer surface inside your Lennox gas furnace. As the burners fire, this component absorbs combustion heat and passes it to the blower-driven air stream while containing flue gases within a sealed path. It is built to Lennox's precise specifications so airflow, temperature rise, and efficiency stay within the furnace's rated design.
Common failure symptoms: Watch for a distorted or wavering burner flame, popping or rumbling on ignition, rust or metallic flaking, cracks along the weld seams, or a furnace that repeatedly trips on its high-limit switch. Any breach in the exchanger can leak carbon monoxide into the supply air, so failure should be addressed immediately.
Why OEM matters: A heat exchanger is a safety-critical combustion part, and only the genuine Lennox 99M79 delivers the exact metallurgy, sealing, and dimensional fit your furnace requires. Non-OEM alternatives risk poor sealing, reduced life, warranty loss, and unsafe combustion. Install the factory part to restore reliable, efficient, and safe heating.