Hello all!

Brand new here, although I've done a bit of searching and poking around to get up to speed. I am replacing a Carrier system, furnace is 1981 and A/C is 1991. Having ongoing issues with both and decided it's time to replace the whole ball of wax.

I've received two quotes already, one from a local Carrier dealer and one from an American Standard dealer. I was surprised at the variance in the quotes and the system specs.

The house is 2-story, about 1,700 sq. ft. Carrier recommended a 2.5 ton A/C and 75k BTU system. The American Standard dealer recommended a 3 ton A/C and 100k BTU system. Efficiency ratings were similar for both systems (13/14seer on the A/C and 93% on furnace).

To correct for extreme variances in the upper floor, both independently recommended a return and second supply line to the top floor, and both suggested a zoned configuration to help further.

Surprisingly, the American Standard system came in at over $1,000 less for the base system despite the higher specs. In both cases we're looking at a "middle" option - i.e. not the Infinity system. The AS dealer was also about $800 cheaper on a 3 zone system.

Both are independently owned, have been in business for quite awhile, and have references.

I'll be getting at least one more quote before making a decision. I'm hoping that I can get some advice to know what to ask the next guy, and questions to direct back towards the vendors I've already spoken with.

A few more specific questions:

1) Is such a price difference common? In general, is there room on quotes for negotiation, or is pricing fairly fixed?

2) Are the variances in specifications all that significant?

3) Both vendors plan to use most of the existing ductwork while replacing part of it near the furnace to make room for the additional supply line. The ductwork appears to be in good condition, and both vendors said with a cleaning it will be fine. Is this generally the case?

4) Are there any specific questions I should be asking? Are there tricks I should be aware of, or are there system components that should be replaced that vendors will try to re-use to save or bid low?

5) The Carrier systems use a Carrier thermostat with humidity control, and the American Standard system quoted White Rogers thermostats. I'm guessing there's no real significance between thermostats except for perhaps in the top of the line systems?

Since I'm making such an investment, I obviously want to do my homework over and above the manufacturer literature.