Before You Start
A heat-gain and heat-loss calculation is the first thing to do. An air conditioning system too large will cause short cycles and waste energy. A system too small would run constantly and not cool your home properly. All heating and air conditioning contractors can do a Manual-J heat load calculation and size your system properly.
If you have the attic and basement space needed, two systems for a two-story home is most efficient. The attic system will cool the bedrooms upstairs while the first floor system would be off, or set at a higher temperature. Saving energy while you sleep comfortably is good for everyone.
You Have Options
Some regions call for heat pumps. A heat pump produces cold air in the summer and warm air in the winter. Many consumers choose the heat pump as a back-up source of heat. The cost of a heat pump condenser is a little higher but it is worth it.
There are high efficient Hepa air filters on the market. These filters capture tiny particles and debris that would slip right through a regular filter. Electric filter systems zap tiny particles that are whizzing through it, much like a bug light.
Mini-split Air Conditioning Systems
The rave today is the mini-split systems. If your attic or basement cannot support a conventional installation, the mini-split is the answer. The units consist of an outdoor condenser, an air handler that hangs on a wall, a drainage hose, and copper tubing between the two.
They are great for problem areas in a home that already has an air conditioning system. Today you can have one outdoor unit and up to four air handlers. They work independently and each has its own remote control thermostat.
Unless you are fully confident in an air conditioning company, always get at least three estimates. This will give you a better idea on what the price for the job is. Make sure they are using the environmentally friendly R-410A Freon. The older Freon R-22 will be phased out by 2020 and the cost is rising each passing year.
Source: Russ Teed, I am a heating and air conditioning contractor.