Lennox 59M03 Flue Transition Kit

The Lennox 59M03 Flue Transition Kit (mfg part LB-106783A) is a critical OEM component designed to manage combustion exhaust and condensate drainage in high-efficiency 90% AFUE furnaces. As a direct replacement for Lennox 18J20, 18J2001, 59M0301, and Armstrong R41093-001, this kit standardizes the flue transition assembly for series including the G26, G32, and 90UGF models. It is specifically engineered to improve water drainage into the cold end header box condensate trap, preventing moisture buildup that can lead to pressure switch trips or secondary heat exchanger corrosion. This kit includes the flue transition assembly, a drain hose assembly, and a 1/8-inch plastic NPT plug. It is built from high-grade, corrosion-resistant materials to withstand the acidic nature of furnace flue gas. When performing a Lennox furnace exhaust repair, using this genuine Lennox 59M03 kit ensures a airtight seal between the heat exchanger and the venting system, maintaining system static pressure and HVAC ventilation safety protocols.

• OEM Compatibility: Replaces outdated Lennox 77K31 and 67K45 series to provide a universal fit for G26, G32, and 90UGF units.
• Enhanced Condensate Management: Redesigned geometry optimizes flue gas moisture drainage, reducing service calls related to stagnant water in the transition.
• Installation Ready: Includes the 73-3/4 inch drain hose assembly and NPT plug for a complete furnace flue transition swap-out.
• Durable Construction: Fabricated from galvanized and composite materials to resist thermal fatigue and chemical degradation from combustion byproducts.

Which Lennox models are compatible with the 59M03?
This kit is the primary transition for G26, G32, and 90UGF series furnaces. It serves as a universal Lennox flue transition to replace several previous part iterations including 18J20 and 67K4501.

Can I use this for non-Lennox brands?
While primarily a Lennox part, it is a cross-referenced direct replacement for Armstrong R41093-001 and certain Concord or Ducane equipment utilizing the same heat exchanger chassis.

Does this kit resolve water leaks at the flue?
Yes. If the existing exhaust adapter is cracked or the drainage port is restricted, this 59M03 replacement restores proper condensate flow to the trap, preventing external leaks and internal blockage.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.