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Electronic Leak Detection
Electronic leak detection is a critical part of any HVAC technician's common practice. Unfortunately, it is also one of the most common sources of misdiagnosis. Here are my tips to make your leak detection more successful:
Use Your Detector Second
Before starting to use your detector, STOP! Look for signs of leaks and corrosion throughout the entire system. I see so many techs who use an electronic leak detector with a very large leak when they would have been better served pressurizing and pinpointing the leak with soap bubbles.
Get a Good One
Use a high-quality leak detector. Hint: if it costs less than $300, it probably isn't great. I'm a fan of the H10G and the H10Pro, although we are testing the Tifzx-1 as a possible option on the recommendation of a few good techs I trust.
Test Your Tools
Check your detector and make sure it actually works EVERY TIME. The H10G has a reference bottle for testing… USE IT.
Let it Warm Up
Many leak detectors require a warm-up time for the sensor. With the H10G, I allow it to run for at least 5 minutes before I start to use it.
Start at The Top
Most refrigerants are heavier than air, so starting at the top and working your way down will help keep you from picking up a leak below the actual point of origin.
Move really slow. When you do get a hit, remove the wand, let it clear, and go back to the same point a few times before calling it a leak. Once you think you've found a leak, attempt to use bubbles to fully confirm.
Use Common Sense
No matter what leak detector manufacturers tell you, there ARE other substances that can trigger your detector. Refrigerant can also move from one place to another due to drafts. I have seen several cases where chemicals in a garage are triggering the detector. I've also seem cases where a technician has misdiagnosed an evaporator coil because of a chase leak where the refrigerant was being pulled from beneath the unit into the return. Look around and make sure there is nothing causing interference.
Before you condemn that coil, BE SURE. Use all of your resources to positively confirm the exact location of the leak. A little patience goes a long way.