ESCO Air Conditioning Practice Exam 2026 - Free AC Certification Practice Questions and Study Guide

To effectively remove moisture from an HVAC system, achieving the lowest possible vacuum level is crucial. When the system is evacuated to a very low pressure, water vapor and other contaminants can be effectively removed.

By doubling the evacuation to 500 microns with a medium vacuum pump, the process ensures a more comprehensive extraction of moisture. A medium vacuum pump is designed to reach satisfactory vacuum levels, and doubling the process—which involves evacuating, breaking the vacuum, and then evacuating again—improves the efficiency of moisture removal.

Evacuating to 500 microns indicates a good level of vacuum, where residual moisture can be minimized. This is because at this low pressure, the boiling point of water decreases significantly, allowing moisture to evaporate from the components of the system. Once the moisture evaporates, it can be effectively pumped out.

In contrast, alternative options either do not achieve as low a vacuum level or suggest single evacuations, which may not be as effective in moisture removal. While some other options imply the use of a deep vacuum pump, the combination of double evacuation and a medium vacuum pump provides a practical balance between efficiency and capability for this specific moisture removal task.