Anyone heard of the plastic evaporator drain pans melting?

Do you mean the ones under the indoor AC coils in a home HVAC system? I had some melted on my HVAC by the heat of the gas furnace. The evaporator stack (the upside down V in the plenum above the furnace) had melt-through on the lower pans which allowed the condensation to trickle down through the furnace into the catch pan. Of course the catch pan had no drain and the cutoff float switch was ineffective so there was more than a bit of water running before I noticed it. The installers replaced the evaporator and attached pans at no charge beyond my inconvenience but they refused to install the "upgrade" evaporator which had pans which appeared to be thin brass instead of plastic. I've had no repeat in the several years since.

Pretty common knowledge, I thought! With oil furnaces and a plastic pan "A" coil you need to give the pan a foot or so of head room. On gas furnaces it is not a problem. Greg

Typical clearance recommendations for the units I've seen are 6 inches....