Arkansas HVACR NewsMagazine May 2024

HVACR NewsMagazine May 2024

Tech News

Vacuum: Moisture vs. System Written by Don Gillis with Chemours and appeared in the April 5, 20224 of HVAC School

1. The system is still contaminated with

moisture. (Possibly trapped under the compressor oil.)

If the system indicates moisture, a multiple evacuation with a nitrogen sweep will significantly reduce the amount of moisture in the system.

Evacuation helps remove contaminants, like moisture and non-condensable gases, from HVAC/R systems, especially ones that are put into service for the first time or put back into service after a repair. Even though pulling a deep vacuum has always been a best practice, it will be required for systems that use the new A2L refrigerants. Before a system is ready to be charged with refrigerant, we must pull a deep vacuum on it to do a decay test. The rate at which our vacuum decays lets us know if our system is dry and tight enough to operate normally. Everything leaks a little, but the decay test sets a threshold that we don’t want to exceed. If our vacuum decays beyond that target, that means we have some problems we need to address. If the leak rate has still not decreased, then one of two things may be happening: