An economizer control contains three automatic dampers, one for exhaust air, one for outdoor air, and one for:

An economizer control contains three automatic dampers, one for exhaust air, one for outdoor air, and one for:

• A. Cold plenum
• B. Supply Air
• C. Return Air
• D. Hot plenum

Answer: (C)

In economizer control, you manage three air streams with dampers to balance ventilation and energy use: outdoor air to bring in fresh air, exhaust air to vent some indoor air, and return air to recirculate air back to the system. The third damper is the return air damper. It sits in the return duct and adjusts how much air returning from the occupied space is mixed with outdoor air before it goes through the coil. This allows the system to favor outdoor air when conditions are favorable, saving energy, while still maintaining proper airflow, temperature, and pressure balance. Cold plenum and hot plenum describe duct spaces, not dampers, so they aren’t the damper in this setup. Supply air refers to the air being delivered to the space, not a damper component. So the damper completing the three-damper arrangement is the return air damper.

In economizer control, you manage three air streams with dampers to balance ventilation and energy use: outdoor air to bring in fresh air, exhaust air to vent some indoor air, and return air to recirculate air back to the system. The third damper is the return air damper. It sits in the return duct and adjusts how much air returning from the occupied space is mixed with outdoor air before it goes through the coil. This allows the system to favor outdoor air when conditions are favorable, saving energy, while still maintaining proper airflow, temperature, and pressure balance.

Cold plenum and hot plenum describe duct spaces, not dampers, so they aren’t the damper in this setup. Supply air refers to the air being delivered to the space, not a damper component. So the damper completing the three-damper arrangement is the return air damper.