I am having a new furnace installed, I need to know what the difference is between a horizontal furnace and a lowboy? My job has just been switched from the horizontal to the lowboy and I want to make sure that it is just as efficient and will properly heat my home. Thank you:confused:

A low boy usually is used for a basement install. A horozontal can be used in a attic or crawl space. The efficiency rate will be posted on the furnace or ask your contractor for that information since he will have it for your particular model of unit.

If this lowboy is going to be installed in the attic in the upflow position are they going to put a secondary condensate pan under it? This would some be thing I would want to consider in installing either furnace. I have seen these furnaces installed above a return air grill to save money on duct and labor(noisey)
The efficiency of the furnaces can be compared with the AFUE number, the higher the number the higher the efficiency. Good luck, Mike