I have a 6 year old custom home (4800 sq ft total - second story 1700 ft, first story 2000 ft, finished basement 1100 ft) in central Ohio. When the house was built, we requested a zoned HVAC solution but were talked out of it by the builder and HVAC contractor (something I have never gotten over, but water under the bridge now). The installed solution was a 4 ton Rheem 90+ gas furnace and a 4 ton WeatherKing (Rheem contractor grade) A/C. We have never been happy with the heating/cooling in the upstairs of the house, especially in the 2 bedrooms furthest from the furnace.

Last week our A/C failed when we got our first hot, humid day and we found out we have a major refrigerant leak. We have talked to 3 service techs/contractors and 2 of the three said it isn't worth trying to repair the A/C after they tried and failed to determine the location of the leak because of the size and quality of the unit. The third thought it might be worth trying to repair, but only for use for the first floor of the house because he doesn't believe it is large enough to service the whole house adequately (although he couldn't find the exact location of the leak either and admits that until they find it, the cost of repair is unknown).

We have gotten 3 different potential solutions from the three contractors. All three companies come with either good personal recommendations and/or reviews from other resources (Angie's List, etc.), so I believe all three are trustworthy and would do a respectable job on an installation. 2 of the 3 did heat-loss analysis. All three also say that the furnace is in fine working condition; however, as it is single stage, it is not compatible with high-efficiency 2 stage A/C units even if I did want to continue use of it.

The first proposal is to replace the system with a new 5 ton furnace and A/C. The A/C would be 2 stage and the furnace would be 2 stage with a variable speed blower. The equipment is branded with their own label (Atlas-Butler), but it is manufactured by United Technologies and carries a 10 year parts/labor/maintenance warranty. This contractor did a heat study. The proposal is in the $14k range.

Second proposal is for a new 4 ton furnace and A/C. Equipment would be Rheem with a 2 stage A/C and furnace would be a modulating unit with variable speed blower. This contractor did not do a heat study, but inspected the trunks and ductwork and assessed that 5 ton might be too much for the existing work, and with 75% of the basement finished, major rework of the trunking and ductwork is not a reasonable option. The proposal is in the $9k range.

Third proposal is not yet complete, but this is the one where the contractor wants to repair the existing 4 ton unit, but he wants to disconnect or block the ducts to the upstairs supplies and returns and then put a 3 or 4 ton electric heat pump in the attic to condition the upstairs. All of the supplies and returns would be cut into the ceiling and all ductwork would be in the attic. The initial "ballpark" on this solution is $7k-$8k for the heat pump and install, but don't know about the repair on the existing or cost to replace with a smaller, high-efficiency A/C and furnace. To add to the mix, this contractor installs only Maytag equipment (manufactured by Nordyne), which is not a brand with which anyone I talk to is familiar. The info I find on the web seems to be positive, for the most part (longest parts/labor warranty in the industry at 12 years and stainless steel components are 2 of the things that are mentioned frequently), but as Nordyne has only licensed the Maytag name for about 2 years, there isn't any long-term data out there yet.

The third proposal interests me from the standpoint of specifically addressing the issues in the upstairs; however, I have a lot of concerns with what happens to the airflow in the existing ductwork when some supplies are disconnected and others are blocked at the far end as well as potential air leakage though all those new cuts in the ceiling. Oh, and having to get up into the attic to change filters doesn't thrill me either.

All three solutions seem workable on the surface and I am sure all would be improvements over the initial system, but I am truly at a loss to determine which it truly the right way to go. (To make myself even crazier, I have contacted a couple other highly recommended contractors that specifically use Carrier and Trane equipment just to get bids on that equipment for comparison).

Your comments and advice are appreciated. Even though hot summer weather is on the way, I am making sure to take the time to investigate every option and make sure we do this right so we aren't kicking ourselves down the road for not getting this right this time around.