OEM Lennox Furnace Heat Exchanger Assembly — 33M64

The genuine OEM Lennox 33M64 heat exchanger assembly is the core component that transfers combustion heat to the air moving through your Lennox gas furnace while keeping flue gases fully separated from your home's breathing air. Engineered to exact factory specifications, it restores rated heating output and safe operation to compatible Lennox furnace models.

A failing heat exchanger is one of the most serious furnace problems. Common warning signs include visible cracks or rust, a flickering or shifting burner flame, soot buildup, unusual odors, and — most critically — the potential for carbon monoxide to enter the airstream. If your furnace has been red-tagged or a technician has identified a compromised exchanger, prompt replacement is essential for safety.

Choosing an OEM Lennox 33M64 matters because the exchanger's alloy, wall thickness, and weld geometry are matched to your furnace's specific firing rate and airflow. Aftermarket substitutes can warp, crack prematurely, or fail to seal properly, undermining both efficiency and safety. Installing the factory part ensures a precise fit, correct thermal performance, and continued warranty compliance for your Lennox system.