Originally Posted by techpappy
I don't understand what you mean by "problem with condensation with hi eff units" The condensation (on a condensing type furnace) is produced on the combustion side of the secondary heat exchanger and is exhausted to outside so, does not affect your supply air. Otherwise, your application should work just as well as the old system.
What I mean is the possibility of the condensate drain freezing increases with high efficiency units since the ambient air in an attic could drop below 32 degrees. And since I have septic and not sewer, I'm not sure if it is ideal to have it drain on the inside of my home.