OEM Lennox 65K Aluminum Heat Exchanger — 99W43

The genuine OEM Lennox 99W43 heat exchanger assembly is a 65,000 BTU aluminized-steel unit engineered for your Lennox gas furnace. It transfers combustion heat into your home's supply air while keeping flue gases safely isolated from the airstream. The aluminized construction resists oxidation and scaling at the high temperatures found in the 65K input class, and the assembly is built to Lennox's exact tolerances for reliable airflow, rated efficiency, and safe operation.

Signs of a failing heat exchanger include cracks or corrosion on the cells, a burner flame that flutters or changes color when the blower runs, soot or combustion odors, and a furnace that repeatedly trips its limit switch and short-cycles. Because a compromised exchanger can allow carbon monoxide to enter living spaces, prompt replacement is a safety necessity.

Only the authentic Lennox 99W43 is matched to the thermal demands of the 65K furnace platform, resisting warping and premature metal fatigue across thousands of heating cycles. Aftermarket exchangers often fit poorly, disrupt heat transfer, and void your warranty. Choose the exact factory aluminized assembly to restore safe, efficient heating to your Lennox furnace.