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  • Craig Migliacco

Why Do Some Evap Coils Leak While Others Do Not? (Quick Tip)

Why do older coils seem to last a long time but ones that are only 10 or 15 years old leak? Energy transfer efficiency was not as much of a concern on older equipment and the tubing used in these older coils had a thicker outside wall dimension. On newer coils made over the last 20 years, the tubing in the coil is thinner, and in most cases, they have an increased surface area on the inside for quick heat transfer. The picture shows this increased surface area.

The problem is, the coils don’t seem to last as long when they have thinner outside walls especially on coils that have a galvanized tin plate on the sides of coil. This galvanized plate rusts and the reaction with the tubing creates leaks where the copper tube elbows are. We are now finding leaks on the tubing in the middle of the coil, leaks where the rusted tin meets the elbows, and leaks due to bad swaging and minimal braze joint coverage.

Be sure to check out our video on Where to Find R-22 & R-410A LEAKS on AC Units!

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