OEM Lennox Heat Exchanger Assembly — 57M90

The genuine OEM Lennox 57M90 heat exchanger assembly is the essential heat-transfer core of your furnace, drawing energy from the burner combustion into the air moving across it while sealing exhaust gases safely away from your home's breathable supply. Engineered to Lennox factory tolerances, it delivers the correct clamshell profile, metal gauge, and heat-resistant alloy needed for proper airflow, rated efficiency, and dependable, safe heating performance.

Signs that the 57M90 should be replaced include visible cracking, rust, or pinholes, a burner flame that lifts or changes color when the blower kicks on, soot buildup around the burner box, unusual odors during heating, and repeated high-limit switch shutdowns. A compromised heat exchanger can leak carbon monoxide into conditioned air, so replacement is a safety priority rather than an optional repair.

Choosing OEM ensures long-term reliability and safety. The 57M90 matches the exact dimensions and materials Lennox specified for your furnace, guaranteeing a leak-free seal against the burner and blower assemblies and full compatibility with the unit's safety controls. Aftermarket parts often vary in thickness and geometry, risking premature failure, poor efficiency, and voided warranty protection.