Which of the following would be an acceptable means of controlling the capacity of air cooled condensers?

• A. Cycle the fan
• B. Vary the fan speed
• C. Install dampers on the condensing coil
• D. Any of the above

Answer: (D)

The capacity of an air-cooled condenser is controlled by how much heat is being moved from the refrigerant to the surrounding air, which you influence by adjusting airflow. If you reduce the air flowing over the condenser coil, less heat is rejected, so the condenser’s capacity drops. If you increase airflow or keep the fan running at higher speed, more heat is rejected and capacity rises.

Cycling the fan changes how long the condenser is actively rejecting heat, which lowers average capacity when the fan is off. Varying the fan speed gives a direct, continuous way to dial in the exact amount of heat removal to match load. Installing dampers on the condensing coil throttles the air passing through the coil, reducing heat transfer and thus capacity.

Because each of these methods can effectively adjust how much heat is rejected, any of them is an acceptable means of controlling condenser capacity.