In an economizer control, three automatic dampers regulate exhaust air, outdoor air, and which other stream?

In an economizer control, three automatic dampers regulate exhaust air, outdoor air, and which other stream?

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

Answer: (C)

Economizer controls balance ventilation and energy use by adjusting three dampers. The outdoor air damper brings in fresh air when conditions are favorable, the exhaust damper vents stale air to the outside, and the return air damper controls how much air from the occupied space is recirculated back to the air handler. This return air path completes the air loop, helping maintain proper room pressure and mixing with outdoor air for efficient cooling. The other streams listed—cold plenum or hot plenum—aren’t the streams these dampers regulate, and supply air isn’t the third stream controlled by the economizer dampers. Return air is the correct third stream.

Economizer controls balance ventilation and energy use by adjusting three dampers. The outdoor air damper brings in fresh air when conditions are favorable, the exhaust damper vents stale air to the outside, and the return air damper controls how much air from the occupied space is recirculated back to the air handler. This return air path completes the air loop, helping maintain proper room pressure and mixing with outdoor air for efficient cooling. The other streams listed—cold plenum or hot plenum—aren’t the streams these dampers regulate, and supply air isn’t the third stream controlled by the economizer dampers. Return air is the correct third stream.