I'm investigating a new AC system to replace an existing 13 year old Carrier system. I'm trying to determine if the new high efficiency 2 stage compressors are worth the additional cost, which generally seem to run about 30% more that the single stage compressors. I'm looking at mainly Carrier or Trane units so far. I'm in Charleston, SC with high summer heat and humidity. The current unit is probably a 12 SEER. The units I'm thinking of are the Carrier single stage 14 SEER or the 2 stage 16 SEER, or the Trane 16i. Living area is about 2000 sq. ft. and sizing should be 4 ton based on the people who've looked at it so far.
If my summer power bill is now $300/month, how much could I expect a 2 stage compressor to save me over a 1 stage? And is one any more or less reliable than the other type.? Many thanks. Wally

 

Best buy right now on Trane is the XL15i or go up the the XL19i this has two compressors in it. the two stage compressors have a unloader in them so the compressor runs all the time for 1 stage or 2 stage. With the 15 or 19 you can stay with R 22 it will be here to2030. For where you are you want a V/S blower also . With it you can have a humidistat on it that when the humidity is very high It will slow down the blower and pull more humifity out of the air. When its done the blower speed will pick back up.. Going with the 15 seer or more you can get a tax credit of $300 and for the V/S blower $50. If you change the heat and AC you can get a 10 year warranty
Dont know the home or load but 4 ton for a 2000 sq ft home seems high. I had 1900sq in FL with a 3 ton. It cost less for a unit to run longer than to stop and start all day.
ED my .02 cents.