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HVAC School - For Techs, By Techs

Nov 13, 2017

Bill Johnson is one of the great educators and writers of our time in HVAC/R. In this podcast episode, he shares some information about his career and some of his top tips on keeping systems leak-free.

Bill began his work on leak-free solutions by using Glyptal on centrifugal compressors. The Glyptal would harden around leaks and seal them up. Nowadays, this is an ineffective approach to sealing leaks in higher-pressure systems.

Bill got the idea to start manipulating pressures to minimize leaks with a standing pressure test for 24 hours at the highest test pressure recommended by the manufacturer. That is Bill's best practice, though it is not always feasible. Bill's rationale is that leaks become much more evident under those testing conditions. (Remember, pressurize the line set. Pressurizing the system can be a bad idea.)

On top of that, Bill recommends pulling a deep vacuum and performing a standing vacuum check according to the manufacturer's guidelines. Fitting inspections are also critical; fittings may be sealed imperfectly, and they are common leak points. Check fittings with a mirror and a good light to look for imperfections and cracks.

Leaks generally occur in piping, not the equipment itself. Moreover, vibrations and corrosion generally cause leaks.

Begin a leak inspection by leak-checking the gauge ports BEFORE attaching gauges. In general, inspect the entirety of the equipment with your senses before attaching gauges. When leak-testing with soap bubbles, make sure to use one that doesn't need to be washed with water, as water can lead to corrosion. (We recommend Refrigeration Technologies Big Blu.)

Most of all, don't leave a job until you find a leak or confirm that the system is leak-free!

Bill also discusses:

  • Being an HVAC teacher
  • Critical charge leak detection
  • Pressurizing with nitrogen
  • Misleading leak detection equipment
  • Torque wrenches

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