I purchased an older home several months ago, and I am in the process of upgrading every thing.
The old AC was installed in 93 and had a SEER rating of 10. The gas furnace was installed in 77 and was probably 50% to 65% efficient.
I had a new AC with a two stage scroll compressor and a SEER of 16 installed with a new two stage gas furnace with an efficiency of 80% and a variable speed fan.
The new system cost me over $1000 more than the standard 13 SEER systems. However, my utility will give me a rebate of $375 for a SEER of 16. I figure the 16 SEER will save me $300 a year compared to the 10 SEER system.
With the rebate, the 16 SEER will pay off the extra $1000 in several years.
My utility will give rebates for added attic insulation so that’s probably one of the things that will get done next.
Both central AC and air source heat pumps are rated according to seasonal energy efficiency ratio (SEER). This is the cooling output divided by the power input for a hypothetical average U.S. climate. The higher the SEER, the more efficient the air conditioner.
http://www.aceee.org/consumerguide/cooling.htm http://www.allqualityair.com/SEER.htm