OEM Lennox Heat Exchanger Assembly — 72K90

The genuine OEM Lennox 72K90 Heat Exchanger Assembly is the essential heat-transfer component of your Lennox gas furnace. Combustion gases from the burners travel through its sealed passages and give up their heat to the blower air stream, warming your home while keeping flue byproducts safely separated from the indoor air. It is manufactured to the precise specifications of compatible Lennox furnace models for an exact factory fit.

Common failure symptoms: years of heating and cooling cycles cause metal fatigue, cracking, and corrosion. Look for a flickering or shifting burner flame, soot or rust accumulation, popping and rumbling sounds when the furnace ignites, repeated lockouts from the limit or flame-rollout switch, and diminished heating. A cracked exchanger can also leak carbon monoxide, so replacement should not be delayed.

Why OEM matters: this is a combustion-sealed, safety-rated part. The OEM Lennox 72K90 matches the exact alloy, wall thickness, and tolerances your unit was certified with, protecting rated efficiency, proper flame behavior, and warranty coverage. Aftermarket substitutes can fit poorly, fail early, and introduce CO risk — always choose the genuine Lennox part.