I wouldn't buy a new system without seeing all model numbers. A few thoughts. What size system are you replacing-both furnace and AC? First please verify the size living area this system will serve. I assume the Infinity 80 furnace is the 70 K model size. Surely, a 1 1/2 ton Performance model is not correct for a home your size. I would think a 3 ton Performance 17 2 stage would be the best choice. You want a Carrier model coil, ALA suffix. Any filter cabinet? New lineset? I never recommend an Infinity furnace without Infinity controller. A nice system if sized and configured correctly. You asked. I answered. IMO This post was edited by tigerdunes on Sun, May 11, 14 at 7:38

Virginia How many returns do you have for basement and main floor? And just to be clear, the AprilAire mdl 2210 is filter media cabinet that is normally attached to the return side of the furnace. The up charge to go to a 95% eff Infinity furnace is absolutely absurd. Makes me wonder about this dealer. Have you considered getting another dealer involved in the quoting process? IMO Here is a link that might be useful: AprilAire Whole House Media Filter Cabinet

Forgot to add - we are adding a new return up and down, new supply up, increasing some duct diameters, replacing plenum, etc. I think ductwork will be much better after the replacement. One thing carrier vendor recommended was repositioned supply feeds so they are not within 17" of end of rigid supply duct (currently flex hoses are connected 6" from end), and adding "scoops" in the duct to direct air towards a media room near the end of the supply duct that gets hot in the summer. He said both of these would help put more air in that room. There is a small return in that room - 7" flex. But return is also near end of the return duct and he didn't feel increasing the 7" duct would do too much vs those supply changes (other vendors suggested increasing that flex duct diameter). The return in a shallow in-wall job with 14x14 grill. No one else suggested these particular changes. Does this sound like a good approach to get more air in that room. (in addition to another independent return to another room).

RE: AC and Furnace replacement NEW DETAILS In Atlanta / one-story / 1,800 sq ft / furnace in attic / easy installation / both quotes from reputable contractors / Already at top of my budget (including rebates/tax credits) without upgrades, but can finance if some upgrades worth it 2 Quotes, both @$6,000 (another Carrier quote of $9-11,000 was so out of budget) Thank you for your insights. See new details/answers below. "What mdl. thermostats? What mdl. evap coils? These are not insignificant details." "Generally you can not pair a two stg. condenser w/out a var. speed furnace" CARRIER 4.0 Ton, 16 Comfort Series Gas Furnace 16 SEER Rating Comfort Series 16 A/C (24ACC648A003) Coil (CNPV 4821) 80% Performance Boost Furnace (58PH0110-16) Carrier Thermostat Edge VERSES TRANE XV80% afue 100,000 BTU Variable Speed 2 stage gas furnace Model# TUD2C100A9V5VA and the Trane 4 ton XR13 SEER high efficiency R410a Puron air conditioner Model# 4TTR3048D1000A and Trane 4 ton all aluminum cooling coil Model# 4TXCC049BC. Trane Touchscreen Super Dehumidification Thermostat Model# XL803 "considering the carrier is a 2 stage comfort series and costs $1,000 less, go with it..." It is $1,000 more (not less). Is the long-term savings of variable speed worth the upfront upgrade cost? "certainly would not recommend the larger XV80 furnace. It will only cost you more to operate..." Thank you, we were questioning this "are you familiar with heat pumps. You want one if you don't have one�" That would be a $600 upgrade. Is this worthwhile? "Dealers are quoting new line sets?..." I don't know what this means? Still wondering *Is there a significant difference between Trane and Carrier parts/engineering? *Is there another suggested brand within range of these systems? *Who are you guys answering these questions? ïÂÂ