The Lennox 46K91 Heat Exchanger is a replacement heating component designed for compatible Lennox gas furnaces and residential HVAC systems. It transfers heat generated during combustion to the circulating air while keeping combustion gases separated from the indoor airflow for safe operation. Engineered for efficient heat transfer and long-lasting durability, this heat exchanger impr... https://www.partshnc.com/heat-exchanger-for-lennox-part-46k91