What two variables are compared when controlling outside air and return air?

What two variables are compared when controlling outside air and return air?

• A. Outside temperature and air flow
• B. Outside humidity and air flow
• C. Inside temperature and air flow
• D. Outside temperature and humidity

Answer: (A)

When controlling outside air and return air, the system uses the outdoor conditions and the actual amount of air being moved to determine damper positions. Outdoor temperature is the main factor that decides whether bringing in more outside air is beneficial or not for energy use and comfort. The measured air flow tells the controller whether the ventilation rate meets the setpoint and how to adjust the dampers to reach that target. Humidity or indoor temperature aren’t the primary signals for this specific control, and outside humidity isn’t directly used in basic outside-air control. So the two variables involved are outdoor temperature and air flow.

When controlling outside air and return air, the system uses the outdoor conditions and the actual amount of air being moved to determine damper positions. Outdoor temperature is the main factor that decides whether bringing in more outside air is beneficial or not for energy use and comfort. The measured air flow tells the controller whether the ventilation rate meets the setpoint and how to adjust the dampers to reach that target. Humidity or indoor temperature aren’t the primary signals for this specific control, and outside humidity isn’t directly used in basic outside-air control. So the two variables involved are outdoor temperature and air flow.