SESK: Stuff Everyone Should Know · sesk.info/epa-why-evacuate
Why do techs evacuate a system with a vacuum pump at the end of service?
To eliminate air and moisture.
- To add oil
- To cool the refrigerant
- To remove air and moisture ✔
Why: A vacuum pump pulls air and moisture out of a system before it is charged. EPA's Core test topics include the need to evacuate a system at the end of service.
Huh, didn't know that: In one Lennox procedure, the first evacuation target is 23,000 microns, about 29.01 inches of mercury.
Deep thought of the day? When you clean a vacuum cleaner, you become a vacuum cleaner.
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References
Answer: To remove air and moisture. A vacuum pump pulls air and moisture out of a system before it is charged. EPA's Core test topics include the need to evacuate a system at the end of service.
- Section 608 Technician Certification Test Topics, US EPA www.epa.gov/section608/section-608-technician-certification-test-topics
Need to evacuate system to eliminate air and moisture at the end of service
Checked 2026-10-10. - Lennox installation instructions 508844-01 www.lennox.com/dA/eb5bdb59f2/508844-01b.pdf
absolute pressure reaches 23,000 microns (29.01 inches of mercury)
Checked 2026-10-10.
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