Lennox 35K56 Gasket

The Lennox 35K56 is a high-performance flue pipe gasket engineered to ensure a gas-tight seal between the furnace flue vent and the chimney or exhaust collector box. Designed for Lennox high-efficiency condensing furnaces, this OEM replacement part is critical for preventing the leakage of hazardous combustion gases into the mechanical room or living space. With a 6.00" ID and 8.00" OD, this fiberglass flue gasket is constructed from high-temperature resistant, insulating materials capable of withstanding the thermal demands of high-duty cycles without degradation. As an HVAC furnace maintenance essential, the 35K56 restores the integrity of the exhaust system, optimizing ventilation airflow and improving overall combustion efficiency. Proper installation of this exhaust flange gasket is required during inducer motor service or flue pipe inspection to maintain system safety and meet code requirements for residential gas-fired heating equipment.

• Ensures a gas-tight seal to prevent combustion gas leaks and maintain indoor air quality.
• Constructed from high-temperature fiberglass material to resist thermal breakdown.
• Maintains ventilation efficiency by preventing air bypass at critical flue joints.
• Precision-engineered for an exact OEM fit on Lennox and Armstrong units, reducing installation time.
• Durable design resists moisture and corrosive byproducts found in high-efficiency furnace condensate.

When should a Lennox 35K56 gasket be replaced?
This gasket should be replaced whenever the flue pipe is disconnected for service, or if you observe any signs of soot, moisture streaks, or visible deterioration around the exhaust connection.

Is this part compatible with Lennox Pulse furnaces?
While primarily used in high-efficiency condensing series, you must verify the specific ID and OD requirements of your model's flue outlet against the 35K56 specifications for a proper seal.

Can I reuse the existing flue gasket during an inducer motor swap?
Technicians recommend always installing a new Lennox 35K56 to ensure a reliable seal, as compressed or brittle gaskets are prone to leaking once the original compression bond is broken.

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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.