I only know of trane manufacturing a coated coil to permanetly solve the issue. Do other brands also make a coated coil?
Unless things have changed in the last couple of years, Carrier, Lennox and Rheem/Ruud don't, we just order a new coil and ship it off to get the Technicoat treatment.
Unless it is a warranty situation, we do the same with Trane coils. The Technicoat process coats everything but the drain pan. In addition to permanently solving the DSS issue, it protects the tube sheet from rusting out, and the copper tubing from formicary corrosion.
The coated coils from Trane only have the fins coated, so while they solve the DSS issue, there is still potential for the formicary corrosion and rusted tube sheet issues.
If more government is the answer, then it's a really stupid question.