What is the primary purpose of AHU mixing dampers in building HVAC?

What is the primary purpose of AHU mixing dampers in building HVAC?

• A. To introduce outside air for cooling to reduce energy use and supply fresh air into the building
• B. To increase humidity
• C. To seal the ductwork
• D. To filter particles only

Answer: (A)

Mixing dampers in an AHU control the blend of outdoor air with return air. Their primary purpose is to bring in outside air to provide ventilation and, when outdoor conditions are favorable, enable economizer-style cooling so that fresh air helps condition the space with less energy use. This dilution of indoor air also supports indoor air quality by introducing fresh air and meeting ventilation requirements. They are not primarily for increasing humidity, sealing ductwork, or filtering particles—the latter functions come from humidity control (in other parts of the system), duct seals, and air filters, respectively.

Mixing dampers in an AHU control the blend of outdoor air with return air. Their primary purpose is to bring in outside air to provide ventilation and, when outdoor conditions are favorable, enable economizer-style cooling so that fresh air helps condition the space with less energy use. This dilution of indoor air also supports indoor air quality by introducing fresh air and meeting ventilation requirements. They are not primarily for increasing humidity, sealing ductwork, or filtering particles—the latter functions come from humidity control (in other parts of the system), duct seals, and air filters, respectively.