It's complicated comparing what we have now because what we have is three systems that combined are way oversized. The house is in Georgia so proper A/C is key. It's about 2700 sq ft, 1.5 story (meaning there are two small guest rooms upstairs but most of the house is on first floor) and has had foam put in the attic (same floor as the guest rooms). I'd go with a different contractor but SO seems to resonate with this one since he is so highly recommended by people who put in whole new systems like ours. He has done zones for others and we did see the Manual J. We even went to one person's house and looked at his whole system including the zoning to check out the workmanship as best we could tell. But I guess I'm wondering if either Amana or EWC has put out some new equipment that could account for us being the guinea pigs. Knowing this is a big investment we are keeping a long time, I want to do all I can to get it right. This post was edited by cas20 on Sun, Feb 10, 13 at 15:40

If I did not know better I would swear that this info was about me. In any case I am in the same ship. Last Oct I replaced the accumulator at the cost of $800 and then last Thurs the compressor died. Well I am hard pressed to put another one in as the system is 12yrs old. so now I have a 10seer unit and that is out of date. Seems to me that I am getting a new system. Problem is which one. I am in Mobile Al so the Heat pump is pretty good here. I have 3 proposals. 1- 13seer $4838 Merv 10 filter sys. Or #2 15seer $4990 merv 10 or #3 16 seer 2stage cooling and Air Handler with Var spd blower...$7040. So there is a $2000 diff here and I do not know if I am going to get 2k worth of savings to warrant..Help!!! BTW that is total prices.

Thanks Tiger and Harlem. 3rd quote came in yesterday (partially, explained below). This is one of the larger and better reviewed contractors in the area. Interestingly they do a fair amount of work through Costco and are the only sub in the area that gets referrals from them. They only quote Lennox at an initial visit, but if pressed will also quote Rheem/Ruud. This shop's "comfort specialist" seems to be the most credible for a few reasons (why do all the larger contractors in my area refer to the sales people as "comfort specialists"? Makes them sound like they're in the world's oldest profession...). 1) I've mentioned previously I'd like to do some rezoning, but I haven't gone into detail as I thought it was pretty minor. Our main house was built in 1990 with about 3,000 sf under air. In 1999 a previous owner built an 850 sf addition that includes two kids bedrooms and a bathroom and turned one of the original bedrooms into a play room that you enter to get into the addition (about 150 sf). At that time they put in the two existing units, a 5 ton for the main house and a 2 ton for the addition (I originally said they were Lennox but are actually IPC). Because of the layout, in my mind it makes sense to rezone the playroom so it feeds off the smaller unit. The first two contractors said "no problem, it will just take some additional ductwork (ka-ching) and by the way you might want to make it a 3 ton unit now. 3rd contractor said he wouldn't do this since his load calcs showed it would make a 5 ton unit oversized for the remaining space. 2) Like the other two contractors, he pointed out that the 5 ton unit had serious air flow issues. His recommendation on the return side was the same as the first two(add two returns), but on the supply side it was different. The first contractor suggested increasing the diameter of all the supply ductwork ($1900 worth of work), and the second said supply was not an issue. Third contractor said supply absolutely is an issue (and showed me pictures and sizes of the ducts explaining the airflow through each), but thought the best solution would be to add two medium size supplies. In his opinion, increasing the duct diameters without changing the size of the existing vents would cause problems. Plus, his way is more cost effective, or maybe his pricing is just better. Additionally, he pointed out that the condenser fan space needs to be adjusted. They are in a fairly tight area, surrounded on three sides by a four foot privacy wall. He would space the condensers further apart and also suggested we have someone cut vent holes into the wall as there isn't enough space to get good ventilation. Great advice. Finally, he showed me pictures of the existing plenum from the two ton unit which is angled like a roof (two 45 degree angles) off the air handler. They would replace this with a box like plenum which he says is better for airflow - makes sense to me. The Lennox systems seem pricy, about $16,000 total for 5 ton and 2 ton xc21 units with corresponding air handlers (CBX 32MV) and I-comfort controls. He will "throw in" a high efficiency filter set-up - 5" filter at airhandler, removes 95% of microns, $100 replacement cost annually per unit - and a high grade UV light for both. He's going to give me a quote on the Rheem/Ruud units which I think will come in about $13k, similar to the second contractor. So is it worth paying almost 25% more for Lennox vs Rheem/Ruud? Per consumer reports the complaints are about the same for both. Is the technology and equipment that much better on the Lennox or am I paying for branding and "american-made?" And if I'm going to pay about $16k for the Lennox, is it worth paying $17k for the Trane system which as Harlem pointed out are 2 stage 2 compressor and seem superior at higher SEER? If so, I can't use the third contractor because he doesn't sell Trane. Final contractor is coming in tonight. They are the market leader in the area, sell all makes/models, and have a great reputation, although they are thought to be expensive. I'll update when I get his recommendations/quote. Thanks for your comments and reading through my insanely long posts.

Attic heat gain on ducts can be considerable so yes, it can negatively impact performance & efficiency. Starting over using the best materials properly installed you can minimize that but I would expect some cost of operation increase. The right way to design a new duct system is do a room by room load calc. That will tell CFM needs for each room. Then a good contractor will use duct sizing methods based on ACCA's Manual D to get it right. Unless someone has particular allergies, I'd skip the electronic cleaner and just use a good media cleaner. And yes, 5 ton for 2100 sq ft seems steep. But only an accurate load calc will tell.