Tracey - some points of reference for out local climate/economy Nobody uses anything but flex duct at R8(code in attic and used elsewhere for simplicity). Our original HVAC budget was $13 and we spent $20. One contractor was $30 for metal ducts. Original was Seer 13 with no frills. We got Seer 15/16 Heat pump with gas backup down/electric up. Variable speed. 2 stage. Zoning. Total of 7 tons - 4 down, 3 up Your specs are typical in that they are not very informative. They don't give size - usually what they'll do is say that they can maintain 20 degrees cooler than outside and ?? degrees warmer. If you have the $$, seer 15 is generally worth it. I think dual fuel (ie gas and HP) is worth it. Variable speed and 2 stage are more comfort items - worth it if they are worth it to you (the other 2 are worth it in $$ saved). If you have the land and the $$, geothermal is worth considering. To throws numbers around, I suspect we would have spent $40 for geo - down to $27 after tax credit. If you have land, the geo should be less - perhaps down to $20 after tax credit. You can then not have gas, longer life of Pumps, quieter operation, no external pieces and of course energy savings. Geothermal is the one of the few options for tax credits on new construction. In my situation, the money saved was not worth it in just $$$. Lastly - there are a few items for our climate worth mentioning (forgive me if I have done this before). R-40 in the attic cost me $200 and reportedly saves $50 a year (code is r-30). Radiant barrier in the attic gave similar numbers. Energy star certification cost me $850 (or so) but saves me 5% on gas and electricity for life (Progress Energy and PSNC) - payback about 8 years. The extra insulating they do with energy star (cost hard to figure) all makes a ton of sense - mostly using foam around windows and doors - which I think cost $200. They also install backing behind tubs/soffits/on attic walls - that is hard to figure cost of since it went to the framers

As far as your ductwork, is it metal or fiberglass? You can't clean fiberglass. Trane and American standard are good units but for the extra price and the fact that you are looking to save money, it might be a great Idea to check with a Local NuTone, Tappan, or Westinghouse Dealer. These are Nordyne produts. You just might be able to get yourself a 16 seer Split heat pump with a Var speed blower motor on the indoor unit, and a 2 stage compressor on the outdoor heatpump. Since this system would qualify for the tax credit you would get $1500.00 off, or look at it like this. You would get free ductwork. All this for what you will most likely pay just for the Trane system. As far as warranty, Trane nor Carrier can touch the Nordyne products warranty If you go with the Nordyne you will get 10 years all parts and 10 year quality Pledge. If the compressor fails for any reason within 10 years, you don't just get a new compressor you get the entire outdoor unit along with labor allowance to replace it. Also the outdoor fan motor on the nordyne never has to be oiled. Trane just gives you a new compressor. Better warranty, more for your money, less maintenance. One more thing you don't need a seacoast kit for the Nordyne product. www.nutonehvac.com check out that website and you can see pics of the units.

Before the evaporator froze up was there good airflow indoors? It could be low on refrigerant; could have a restriction somewhere in the refrigerant lines, at the metering device, or the filter drier; or could be quite low on refrigerant. There is a problem or two that the HVAC technician has to find and fix.

Okay, I found the info in the installation manual. The 2-stage scroll compressor has solenoid control of valves. When the valves are open, some of the gas which would be compressed is dumped from the first compression pocket back to the low side of the compressor, thereby decreasing the displacement and capacity. Which brings me to a related question. When the A/C compressor is on Low, the expansion coil is effectively quite oversized. The Infinity controller should slow down the blower to match the load. Generally speaking, what is the disadvantage of having a coil larger than necessary?