Help with Trane XE 90 furnace

[Martin Karl]

Had this Trane XE 90 furnace today. Notice all the rusting. what is causing this? also on the outside the icicle on the exhaust. Can I get your opinions on this. Let me know what more info you need.
Model # TUX080C942C1 Serial # P443H3F7G
I assume it was made in 1999.
Thanks!

[Joseph Hagarty, CMI]

Poor installation of the air intake / exhaust piping will cause this.
Blockage of the drains would be indicated by more extensive corrosion.

defer back to the Contractor that installed the system (maybe still under warranty) to correct

http://www.nachi.org/forum/f2/trane-xe90-rusting-68135/

[Rick Strand]

Where is the condensate from the furnace and A/C draining to???? The piping is there but where is the drain exit?

[Martin Karl]

It runs to a floor drain.

[Rick Strand]

Is it at the low point of the drainage piping? Does it run towards the rear of the cabinet on the right side? Sure looks to be the result of backed-up / leaking condensate which is quite corrosive. Improper drainage would also leave more vapor in the exhaust which could contribute to the icicles on the exhaust.