It'll certainly, on average, cost more to heat than cool. A lot of areas now impose summer electrical rates which are higher than winter rates so they may be close. As for determining the cost effectiveness in relation to higher initial costs of higher SEER ratings, there may be more sizzle than steak. Compare the increase in energy savings with the higher efficiency units as opposed to the actual higher cost of a higher efficiency unit. The expected life cycle on a unit is 10 years so figure the energy savings you will experience in your area and see if it will shadow the initial and ongoing maintenance costs. Keep in mind the newer units also have a maintenance schedule that will be required by most companies, which is going to increase those costs. If your energy savings is more than the overall cost of the unit in a 10 year period, then it's worth it. But for the most part, I think you'll find it won't.

Thank you for all of the input. A third party did clean our ductwork not long ago, and told us it was in great shape. A HERS (Whole House Home Energy Rating), duct leakage testing is mandatory in CA when installing or replacing HVAC system. It was included in both bids, $250.00. Part of the bids were to do resealing and add insulation. As to the 5 ton versus 4 ton, I gave you the wrong sq. ft., it is a little over 2,500 sq. ft. Both contractors recommend the 5 ton. When I questioned again after reading your responses, the first bidder again recommended we stay with a 5 ton. Trane: Contractor said our space was to small for the coil? on the Trane. If he went that way, would need to use an after-market part to make it work, and didn't want to do that... Mike, we do get hot weather: few weeks of 90's but can get up to 110 infrequently in the summer. 60's day but down to the 40's night, occasionally 30's, winter, but try not to overuse our units. Keep it in the mid to high 80's summer, high 60's winter. Turn off at night. Try to do our bit for energy conservation. Bid on XC13 AC condenser, $200.00 more on first bid. 90 K BTU ML180E model furnace with 5 ton rated blower, $600.00 additional. Total $6,549.00 I hope I answered all the questions. Thanks again.

Again would like to see model numbers for outside condenser and inside air handler. Just so you know, Goodman is a low end brand still sold more on price than quality. If price includes new ductwork, then probably OK. You want the ductwork properly sized, sealed and insulated R8 minimum.. How many returns? Two at a minimum strategically located for best airflow and comfort. Interior doors must remain open or have clearance for airflow. I prefer ductwork at least to have metal trunk lines and flex runs. What plans to filter return air? Know the warranty. IMO

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