Arkansas HVACR NewsMagazine May 2022

HVACR NewsMagazine May 2022

Tech News

the insulation and get a hit with your detector through the tear. Otherwise, you will have to do a line isolation test. Before you start a line isolation test, be sure to do another thorough refrigerant leak detection at the connections and on the coils. Double-check for corrosion and oil spots throughout the system and keep all of your electronic leak detector best practices in mind. If you fail to find a leak despite using an electronic leak detector, bubbles, and a pressure test, then you can think about starting the line isolation test. You would start by pumping down the system to get as much refrigerant into the condenser as possible. Recovering the refrigerant and recharging the system is not a good idea, as the refrigerant may become contaminated by the recovered refrigerant and sludge inside the recovery tank. So, it’s best to pump down the system, close the service valves, and recover only the residual refrigerant. Isolate the lines by cutting them near the evaporator coil and pinching them off. If possible, pinch off both sides and install a service port on one side. Then, pressurize the individual lines and the evaporator coil. I generally recommend pressurizing the lines to 300 PSI, but you need to follow the manufacturer’s low -side pressure protocol for the evaporator. For best results, use high-quality pressure probes to monitor the pressure drop over time. Wait at least an hour for your pressure test results. In that time, do a thorough leak detection on the condenser coil again. If you How to do a line isolation test

still have time, take care of other important tasks at the job site, like cleaning the drain.

Once you find the leak source, you must rectify it. If the leak is in one of the coils, you’ll probably have to quote the coil (though you may be able to patch an aluminum U-bend). If the leak is indeed in the line set, you may need to rerun and quote a new line set. You may also need to cut out your liquid line filter-drier and braze in a new one. After you’ve rectified the pr oblem, do a standing pressure test and a bubble test. If the system passes the test, you can pull a deep vacuum (below 500 microns) and open the service valves to put the system back into service. If you want to learn even more about refrigerant leak detection, I highly recommend checking out the articles and videos linked throughout this mega-article. I also suggest reading Refrigeration Technologies’ Leak Detection Manual, which goes over the basics of refrigerant leak detection, some products you can use to help pinpoint leaks, and some practices for detecting unique types of leaks. You can read that manual HERE. The thoroughness of this article demonstrates why we so greatly appreciate Bryan Orr and the HVAC School for sharing their information. We encourage you to subscribe to their newsletters to keep up with the most current training online.

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