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Ac Purge

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Paul B_5
Paul B_5 Member Posts: 60
in A-C, Heat Pumps & Refrigeration
Mini split with precharged outdoor unit for up to 25 foot lineset. when connected to new lines on an install are the 25 foot lines in need of a vacuum purge or will it mix OK. How many inches of vacc are reqired??

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  • lee_7
    lee_7 Member Posts: 458
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    Yes you need to evacuate lineset and indoor section. This must be done on all systems with the excepyion of mobile home units that have precharged coil, line set, and condensor. The system should be evacuated to at least 500 Microns on the vacuum gauge. It should hold for at least 15 minutes with a maximum of 100 microns. ( 500 to 600). The deeper the vacuum, the better the system will be cleared of contaminants. Air, or that matter, any contaminants in the system will adversely affect system performance.
  • Eugene Silberstein 3
    Eugene Silberstein 3 Member Posts: 1,380
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    In Addition to Contaminants

    In addition to any contaminants that may be present in the lines, moisture is a big issue.

    Air contains water vapor and, when present in the system will form acid. Acid can cause rapid deterioration of motor winding insulation as well as the breakdown of compressor oil, etc.

    As mentioned, the minimum vacuum level is 500 microns, although 250 is preferred by many equipment manufacturers.
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