Burnham Boiler 8116322 Vent Damper

The Burnham 8116322 5-inch automatic vent damper is a critical electromechanical component designed to improve the AFUE rating of high-efficiency gas-fired atmospheric boilers. This Johnson Controls manufactured unit (frequently cross-referenced as M35MB-2) functions by closing the flue pipe during the burner's off-cycle, preventing standby heat loss through the chimney. It features a high-temp polymer construction and a robust motor-actuated blade system that integrates directly into the 24VAC control circuit. The unit includes a standard 4-pin Molex harness for plug-and-play installation on compatible Burnham-U.S. Boiler Series 2 or Independence models. For contractors, the internal safety interlock switch is paramount; it ensures the main gas valve cannot open until the damper has reached the full open position. This replacement vent damper is engineered for vertical or horizontal mounting, provided it is installed upstream of the draft hood as per manufacturer specifications and local mechanical codes.

• Reduced Standby Heat Loss: Minimizes convective cooling of the heat exchanger during off-cycles to maintain system temperature.
• OEM Compatibility: Exact drop-in replacement for Burnham Boiler model 8116322, ensuring electrical and physical clearances match.
• Safety Interlock: Verified end-switch prevents ignition cycles if the damper blade fails to actuate, mitigating carbon monoxide risks.
• Standardized Wiring: Equipped with a 4-pin terminal plug for rapid interface with existing burner control modules.

How do I troubleshoot a 5" vent damper that won't open?
Verify 24V power at the Molex harness. If the motor hums but the blade doesn't move, check for soot buildup or physical obstructions. If the motor is silent despite receiving a call for heat, the actuator assembly likely requires replacement.

Can I manually bypass the damper if the motor fails?
While most units have a manual service switch, it should only be used for emergency diagnostic purposes. The system is designed to lock out the burner if the damper does not prove open to prevent flue gas spillage.

What is the difference between this and a thermal vent damper?
Thermal dampers rely on heat to expand bi-metal strips, whereas the Burnham 8116322 is an electrical actuator. Electrical dampers provide a tighter seal and more reliable safety interlock verification for modern boiler controls.

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.