{"product_id":"oem-lennox-heat-exchanger-assembly-57m99","title":"OEM Lennox Heat Exchanger Assembly — 57M99","description":"\u003cp\u003eGenuine OEM Lennox \u003cstrong\u003e57M99\u003c\/strong\u003e heat exchanger assembly. The heat exchanger is the heart of your Lennox gas furnace — it transfers heat from the burning gas to the air moving through your ductwork while keeping combustion gases safely separated from the air you breathe. This factory-engineered assembly is built to the exact tolerances and metallurgy of your original Lennox unit for a proper, reliable fit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCommon failure symptoms:\u003c\/strong\u003e A failing heat exchanger often shows up as visible cracks or rust, a flickering or wavering burner flame, soot buildup, unusual odors, or a carbon monoxide detector alarm. Reduced heating performance and short cycling can also indicate a compromised exchanger. Because a cracked heat exchanger can leak carbon monoxide, replacement should never be delayed.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy OEM matters:\u003c\/strong\u003e Lennox heat exchangers are designed with specific alloys, wall thicknesses, and pass configurations matched to each furnace model. Installing the genuine \u003cstrong\u003e57M99\u003c\/strong\u003e assembly ensures correct combustion airflow, rated efficiency, and full compatibility with your Lennox safety controls — protecting both performance and your equipment warranty. Aftermarket substitutes rarely match these exact specifications.\u003c\/p\u003e","brand":"Lennox","offers":[{"title":"Default Title","offer_id":63081076523379,"sku":"LNX-57M99","price":399.95,"currency_code":"USD","in_stock":true}],"url":"https:\/\/nationalhvacparts.com\/products\/oem-lennox-heat-exchanger-assembly-57m99","provider":"National HVAC Parts","version":"1.0","type":"link"}