i'm having a 3rd furnace added to the attic of my garage to provide heating and cooling to the 800sf of finished space above the garage. the other 2 furnaces are in the basement.

the contractor has chosen a Trane X90 series 2 ton system. model # TUC1B040. Horizontally mounted (the roofline is too short for a vertical install.).

he is installing new ductwork to supply 4 nearby rooms. 1 bedroom, 1 bath, 1 laundry, and 1 cedar closet.

he is installing the AC compressor at the opposite end of house next to the other 2. the lines go down 2 stories to the basement, and then over 60ft to the far end of house.

he will install gas line up to the attic. and everything else that goes with a furnace install. he will run the exhaust back through the attic to the far end of the house (as opposed to punching it through the roof above)

price for all this is $7500.

this seems very high. but there's a lot of ancillary work.

does this seem fair?
is the Trane a good system for this application?