An outside air damper is a motorized or gravity-operated device that controls the intake of fresh outdoor air into the HVAC system. These dampers regulate the mixture of fresh outside air and recirculated indoor air to maintain proper ventilation while minimizing energy loss. Building codes typically require 15 to 20 cubic feet per minute of outside air per person in occupied spaces.
Operation and Control
Outside air dampers respond to enthalpy sensors, CO2 sensors, or timer controls to optimize fresh air intake based on conditions and occupancy. In winter, dampers minimize fresh air to reduce heating load. In summer, they can increase fresh air when outdoor conditions are cooler than indoor conditions.
Energy and Health Benefits
Proper outside air damper control improves indoor air quality while reducing heating and cooling costs. Demand-controlled ventilation systems using outside air dampers can reduce energy consumption by 20 to 35 percent. Economizer systems use outside air dampers to supply 100 percent fresh air when outdoor temperatures are suitable.