{"product_id":"oem-lennox-heat-exchanger-assembly-43j45","title":"OEM Lennox Heat Exchanger Assembly — 43J45","description":"\u003cp\u003eThe genuine OEM Lennox \u003cstrong\u003e43J45\u003c\/strong\u003e (reference LB-65729E) heat exchanger assembly is the core combustion component of your gas furnace, transferring heat from the burned fuel to the circulating air while keeping combustion gases safely sealed away from your home's airstream. Because it directly separates flue products from the air you breathe, a properly functioning heat exchanger is essential to both furnace efficiency and household safety.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCommon failure symptoms:\u003c\/strong\u003e visible cracks or rust on the exchanger surface, a flickering or rolling burner flame, soot buildup, unusual odors during heating, or a carbon monoxide detector alarm. Repeated thermal cycling over the years leads to metal fatigue and stress cracks, which are a serious safety concern and typically require full replacement rather than repair.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy OEM matters:\u003c\/strong\u003e The 43J45 is engineered to the exact dimensions, alloy specification, and pressure tolerances Lennox designed for your furnace. Aftermarket substitutes can compromise the combustion seal, void your warranty, and reduce rated AFUE efficiency. Choosing the factory OEM part ensures correct fit, reliable heat transfer, and the safety margins Lennox intended for your equipment.\u003c\/p\u003e","brand":"Lennox","offers":[{"title":"Default Title","offer_id":63081067217267,"sku":"LNX-43J45","price":399.95,"currency_code":"USD","in_stock":true}],"url":"https:\/\/nationalhvacparts.com\/products\/oem-lennox-heat-exchanger-assembly-43j45","provider":"National HVAC Parts","version":"1.0","type":"link"}