{"product_id":"oem-lennox-heat-exchanger-assembly-13x21","title":"OEM Lennox Heat Exchanger Assembly — 13X21","description":"\u003cp\u003eThe genuine OEM Lennox \u003cstrong\u003e13X21\u003c\/strong\u003e heat exchanger assembly (factory reference 612989-27) is responsible for transferring burner heat to the air moving through your furnace while safely containing and venting combustion gases. Produced to original Lennox tolerances, it restores proper heat transfer and maintains the airtight barrier that keeps flue byproducts out of your home's air supply.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCommon failure symptoms:\u003c\/strong\u003e Watch for visible cracks or rust on the exchanger, a burner flame that lifts or rolls out when the blower runs, soot buildup, an unusual combustion odor, frequent tripping of the safety limit switch, or carbon monoxide alarms. A damaged heat exchanger must be replaced, not patched.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy OEM matters:\u003c\/strong\u003e Given its role in both efficiency and combustion safety, the heat exchanger demands exact material and dimensional matching. The OEM Lennox \u003cstrong\u003e13X21\u003c\/strong\u003e replicates the original 612989-27 in metallurgy, gauge, and form, ensuring a leak-free seal, correct airflow, and continued warranty protection. Aftermarket versions can misfit and jeopardize safe venting — choose the genuine Lennox part for a reliable, lasting repair.\u003c\/p\u003e","brand":"Lennox","offers":[{"title":"Default Title","offer_id":63081072853363,"sku":"LNX-13X21","price":399.95,"currency_code":"USD","in_stock":true}],"url":"https:\/\/nationalhvacparts.com\/products\/oem-lennox-heat-exchanger-assembly-13x21","provider":"National HVAC Parts","version":"1.0","type":"link"}