When sizing a condensing unit, at what condition is its capacity usually calculated?

The capacity of a condensing unit is typically calculated at the lowest operating suction pressure. This is critical because the performance of a refrigeration or air conditioning system can vary significantly depending on the operating conditions, especially regarding suction pressure.

When the lowest operating suction pressure is established, it defines the conditions under which the system is expected to operate most efficiently while still meeting the cooling load requirements. Calculating capacity at this point helps ensure that the condensing unit can handle the maximum demand during peak conditions, allowing for effective cooling without risking system overload or failure.

In contrast, considering maximum operating pressure, average room temperature, or ambient temperature may not accurately reflect the performance of the system under real operational conditions. These factors can influence the overall efficiency and capacity calculations, but they do not represent the critical load requirements considered during peak operating scenarios. Therefore, using the lowest operating suction pressure helps technicians design a system that is reliable, efficient, and appropriately sized for the intended application.