Which Coatings Work on Microchannel Coils?
Key facts
| System | Film | On microchannel coils |
|---|---|---|
| PG-S1 | 5–15 μm | Preferred; dip with controlled drain-off |
| PG-W | 5–10 g/m² per side | Suitable for mild coastal and humid sites |
| PG-C | 20–40 μm | Only after reviewing louver pitch; bridging risk |
Why the film has to be thin
Microchannel coils use fine louvered fins brazed between flat tubes. The gaps are narrow, and the louvers are what give the coil its performance. A thick film fills them, raising pressure drop and cutting airflow.
Why dip, not spray
Spray reaches the face of the coil well but the inner louvers poorly. Dipping wets every surface, and controlled withdrawal and drain-off leave a thin, even film.
Braze joints first
Microchannel coils usually start corroding at the tube-to-header braze joints. The coating must reach them fully, which is one more reason to dip.
What this means for your project
Specify a thin-film system applied by dip, ask for the film thickness range and a bridging check in the batch QC, and confirm the coil fits the tank. For very large coils, discuss the method before ordering.
