is a 4-inch diameter vent damper constructed from stainless steel for corrosion resistance. It is a critical safety and efficiency component for 24 VAC gas-fired heating appliances.

The damper remains closed during "off cycles" to trap conditioned air inside. When the thermostat calls for heat, a motor rotates the damper 90 degrees to an open position in approximately 15 seconds, allowing flue gases to vent safely.

The unit is installed in the vent pipe after the draft hood or draft control. It often requires a specific Wiring Harness for connection to the appliance. Specifications

, a series of automatic gas vent dampers used in residential and commercial HVAC systems. These devices are designed to improve energy efficiency by preventing heat from escaping through the chimney when a gas boiler is in standby mode. Technical Overview: The GVD-4 Series The Field Controls GVD-4PL