tigerdunes -- thanks for your input! Much appreciated. That is the direction I'm heading, subject to final price, warranties, etc. (The last quote from Company 2 had the Infinity furnace with the Comfort A/C.) The tendency here seems to be the "1 ton / 500 sf" approach. I've been pushing the final two dealers to really be sure about their sizing by giving them as much info as possible (the number of windows in the house, no insulation, orientation, etc, etc.) vyasmk9 -- I'm on the Peninsula -- as are all of the contractors I've contacted. It just seems that people around here seem to service a smaller area (although I could be wrong), plus I like to support local biz whenever I can. Just FYI, I started by selecting a couple of well-known brand names (Trane and Carrier) and looking on their websites for local dealers. Followed that up with searches for reviews of those dealers on local.yahoo.com and yelp, as well as checks on the BBB. Also asked my electrician and utility company guy for their thoughts/referrals. Not sure what the forum rules are for recommending contractors, so I'd rather ask before naming names. Anyone want to comment?

Based on the information you've provided, sounds like the York quote is the best option, but I don't agree with the 80% modulating furnace. That's a high-end furnace, and going with the 80% version doesn't make sense to me, especially in our region where it can get cold at times (I'm in Maryland). Is PVC venting an issue? The York Affinity is a nice line of equipment. American Standard isn't bad, either, but the equipment that the York rep. is quoting is better in my opinion. 3 tons is a bit much for your cooling load, but it's what you'd have to go with if you went with the Affinity line. The 2.5-ton Latitude unit would be the better fit. With the low stage on the Affinity approximately meeting the cooling load at design conditions (which won't be met on all days), I don't think you'll be getting those long run times that you should with a 2-stage system. Ask the York rep. if he can quote the CZB or YZB 2.5-ton single-stage Affinity unit with a 90+ efficient v/s furnace (modulating or 2-stage). Not sure where the American Standard rep. came up with his sizing. Do you like it cold in your house (68-70)? Did the York rep. do the load calculation?

Thank you for the prompt reviews! Looks like Proposal #1 is the winner so far. Mike ��" the attic fan made a huge difference in second floor comfort. One of the best things I did. Glad your experience was the same. I will look into the 2 stage AC. I will not run the fan or put in an extra return for the humidity/temperature change issues. I will just continue to use my dehumidifiers. They do take care of the issue. I am going to plan on replacing the line set ��" it is easy to get to. What do you think about the drain pan/wet switch that will shut off the AC if there is a leak? Is it going to go off over nothing like a smoke detector I used to have and drive me nuts? Or is it a good idea? I might not have been clear about one thing. Both contractors told me to keep the old air filter set up (Spaceguard High Efficiency). It is the old Aprilaire humidifier that Contractor #1 said replace due to age/parts and Contractor #2 said keep it, parts are not going to be a problem and the only part that goes bad is the solenoid. Keep the old one or buy a new one? Contractor #1 is going to look into the Carrier early failure of heat exchangers settlement. It might only apply to the secondary heat exchanger. The primary one failed on my furnace. I meet with the last contractor tomorrow. I hope to have all the bids by the end of the week. My goal is all new equipment before I have to turn on the heat!

existing furnace is probably oversized...raising temp 4 degrees sounds good but a swing like that does nothing for comfort...I would change out thermostat when you install new furnace...you want an even temp setting to be maintained...add a filter cabinet at furnace return if you don't already have one...for a 1200 sq ft home besides the physical footprint needed, I would get a smaller furnace that can handle your 2 1/2 ton AC condenser...even a 60 KBTU furnace would be oversized. IMO