In general, the more efficient the unit, the more it will cost initially. However, the more efficient, more expensive unit will actually save you money over time as it requires less fuel to cool your home. The typical SEER rating of units manufactured prior to 1992 is about 6.0. Most air conditioners operate at 8 to 9 bels. The quietest units operate at 6.8 bels.
Some air conditioners come additional features that provide greater comfort.
In order to achieve comfortable cooling and dehumidification, the system must be correctly sized. The size of central air conditioning is measured in tons. The following is a rule of thumb guideline for sizing residential systems in Harris and Montgomery Counties. Ton 1,000 - 1,200 sq.ft. Ton 1,200 - 1,500 sq.ft.