Slant Fin 412-705-040 Damper Assembly

The Slant Fin 412-705-040 is a heavy-duty 5-inch automatic vent damper assembly engineered specifically for high-efficiency hydronic heating systems. Designed as a direct replacement component, this motorized flue damper prevents standby heat loss by sealing the vent pipe when the burner is not firing, significantly improving the AFUE rating of the boiler. This assembly features a robust internal synchronous motor and built-in safety interlock switches, ensuring the burner only ignites when the damper reaches the full open position. Built for reliable gas boiler venting applications, the 412-705-040 manages high exhaust temperatures and resists corrosive flue gases. Contractors should verify the wiring harness compatibility and 24V power requirements before installation. This metal-to-metal seal design minimizes thermal drift, maintaining consistent water temperature within the heat exchanger during off-cycles. Replacing a seized or sticking HVAC vent damper with this OEM-spec assembly restores system safety and efficiency.

Key Benefits

• Direct OEM Replacement: Matches original factory specifications for Slant Fin S-Series and Liberty series boilers.
• Thermal Retention: Eliminates the chimney effect to keep the heat exchanger warm during standby periods.
• Safety Interlock: Integrated end switch prevents boiler operation if the damper fails to open.
• Durable Construction: High-grade stainless steel blade and housing resist oxidation and warping from flue heat.

Common Questions

Is the Slant Fin 412-705-040 compatible with 120V systems?
No, this damper assembly is designed for 24V AC control circuits. Using line voltage will damage the internal motor and control board.

Can I manually override the damper position?
Most models feature a service switch for manual operation during maintenance, but for standard operation, the damper must be controlled by the boiler's 24V terminal strip.

What causes a vent damper to fail?
Common failure points include carbon buildup on the hinge points or motor burnout due to improper wiring or high ambient temperatures near the flue.

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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.