$7000 does seem high unless he is quoting higher end units. The indoor coil needs to be replaced to match the outdoor unit. Plus it is what usually is leaking anyway. Since the indoor coil is built into most blower units, chances are it would be easier just to replace all. Today's higher efficiency coils tend not to fit in older air handlers.

I live in Michigan. My home is a colonial with approximately 2400 sq ft. The current heating system, when it worked, was excellent. The house would heat up in a matter of minutes. The temperature also stayed pretty consistent. In the old house we also had the furnace replaced. I hated, hated, hated the new furnace. The furnace would turn on, the house would get warm, then the temperature would go down about 5-7 degrees before turning back on. The air was also super dry and we had never had that problem before. I don't want to make that mistake again. Here's the actual information from the quote: Remove and haul away old equipment. Install Carrier 110,000 BTU 80% efficient furnace with 35ft chimney liner. Install a Carrier 3.5 ton 13 seer central air package with 25ft copper lineset, ac pad, a coil cond (can't figure out what he wrote) pump to pump to laundry. Elect (can't figure out what he wrote) and disconnect. All permits, sheet metal, work, taxes, and cleanup included. Warranties: Furnace - 20 year heat exchanger Parts - 10 year Service & Labor - 2 year Total Cost - $4890 Extras: air cleaner - $200 95% Carrier 100,000 BTU furnace $700 more It seems that it makes more sense to get the 95% or 96% furnace but I really don't know.

I have not been checking recently, but as of a couple of years ago, there was little objective data that indicated that UV lights could do much of anything to help with allergies. I think the return on expensive filters is similar. That would be when added to a system that is functioning well in a home that is kept clean and outside air infiltration is controlled. Of course "allergies" does not really tell much of the story. The most important thing in dealing with allergies is to identify the allergens. If you don't know that, you are stabbing in the dark. Humidity control is going to be very important in S. Florida. Another issue is duct placement and leakage. If the ducts are outside of the house envelope (crawl space or attic) and leak, you are blowing out conditioned air through supply duct leaks causing a partial vacuum in the house. That sucks in hot humid air through any leaks cut in the house envelope. Hot humid air then hits cool surfaces and causes condensation and fungus growth. I have not looked at this for a while, but check it out: My House is Killing Me! The Home Guide For Families with Allergies and Asthma, by Jeffrey C. May, Johns Hopkins University Press, 2001. For building and AC issues in the hot humid South, FL universities have some good resources. So does www.buildingscience.com . If you are going to look at one thing at that site, make it this: http://www.buildingscience.com/documents/insights/bsi-015-top-ten-dumb-things-to-do-in-the-south/?searchterm=top%20ten

"This is true in general but if this was not happening before the replacement, they did something else when they replaced the equipment." It's pretty clear the replacement contractor "did something else when they replaced the equipment." Indeed, based on the information provided by the OP, the replacement contractor 1.) reduced the heat output of the furnace by 2%, 2.) reduced the airflow by 6%, 3.) improved the combustion efficiency by 22%, and 4.) modified the ductwork. The OP needed to restrict the air flow to the 2nd floor prior to the equipment replacement and needs to restrict the flow to the 1st floor now. I see that as a six of one, half dozen of the other issue and a reasonable trade off for the increase in combustion efficiency. Attempting to control two levels utilizing a thermostat located on one level doesn't typically result in comfortable conditions on both levels at the same time. That's what zoning is for. We don't know whether the replacement contractor proposed a zoning option. Absent zoning, balancing dampers will help compensate for differences in the heating and cooling demands of both levels. They may need to be adjusted seasonally or even during temperature extremes in a single season.