INTRODUCTION:

When troubleshooting an HVAC system, finding leaks and moisture can sometimes take longer than fixing them, especially if the initial diagnosis is wrong and repeat trips to the customer are needed. Follow these steps to get fast, reliable answers from the analytics in your vacuum gauge. You can also watch a video of these steps in action, in the field, from a 30-year veteran who says this new process makes his life a whole lot easier! And we didn’t pay him to say that, honestly…..

  1. Test the vacuum pumpVacuumDude
  2. Remove the valve core
  3. Install manifold, hoses and vacuum pump
  4. Install vacuum gauge through core removal tool
  5. Open all manifold valves and core tool valve
  6. Make sure evacuation can get below 500 microns or manufacturer suggested
  7. Close core tool and watch micron rise 

    Below is a summary of the possible results you might see and what they mean:

  • LeakThe “LEAK” result indicates pressure increasing towards atmosphere with rates that are not typically indicative of outgassing alone. Look for a leak that must be repaired.

  • The “PUMP” result indicates a strong pressPumpure descent to vacuum for a system under vacuum pump down. This indicates that the pump is on and operational, otherwise it wouldn’t move at all. Note that, the larger the system, the longer it will take to evacuate. 
  • The “OUTGAS” result indicates evidence of outgassingoutgas. Evidence of outgassing is a pressure trend that is ascending at a rate that is decreasing. Eventually the rate of ascent decreases until the pressure stabilizes. This means either you have to pump more because you have a wet system (there are still water and contaminants), or it is good enough depending on what the vacuum level stabilizes at.

  • The “STABLE” resStableult indicates no particular evidence of venting (LEAK) or out gassing, and is
    shown for slow pump down rates for the benefit of the experience of working with the instrument. This means that the system is probably fine (note that you typically  need to be stable at a number well below 1,000 microns).

    Check out other great HVAC Content here
    This article used screenshots from our Bullseye® micron gauge to visually depict pressure trends in common problems. 

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