Choose a dependable contractor
Choosing the right unit for your home will largely depend on the contractor you choose because he will determine the capacity required. A good contractor will estimate the cooling loads and duct requirements by collecting detailed information in your home and using industry calculations to determine the correct size. (For more information on how to select a contractor, including what questions to ask him, see the article on choosing the right contractor.)
The beauty of a central air conditioning system is that it can distribute cool air through the whole house as opposed to window units which are generally designed to cool a single room. Despite the larger initial cost, a central cooling system can still save you money by reducing your monthly utility bill. If new or modified ductowork is required, then your initial investment will rise. Central air conditioning units also vary in size and efficiency. A common, costly error is to install an oversized unit in the home.
Install the correct type of unit and efficiency level
There are different models, sizes and efficiencies available on the market. The type of unit, for example, a split system versus a single-packaged unit, may depend on the region of the country you live in and the type of home you live in. Regardless of the type of central air conditioner you install, the size and efficiency can have the most impact on your costs.
Get the right size unit for your home
Air conditioner sizes, also referred to as cooling capacities, are measured in British thermal units per hour (Btuh). One ton is equal to 12,000 btuhs. A unit that has too little capacity may not keep the whole house cold, while an oversized unit will cost more and be more expensive to run.
The most expensive part of an air conditioner to replace is the compressor. Air conditioners typically feature a scroll or reciprocating compressor, depending on the unit size and efficiency. Check to see if the compressor has an additional warranty (e.g. 10 year compressor warranty), separate from the standard cooling system warranty
Invest in a proper thermostat
Finally, if you are gone during long periods of the day (or night) invest in a programmable thermostat. With a programmable thermostat, your cooling system can use less energy while you’re gone and then adjust itself so the house temperature is comfortable when you arrive.
And if you are wondering whether you should turn off the air conditioner so you can open a window to enjoy a break in the warm weather, here is some advice: do not continually turn on and off your air conditioner to adjust to the changing warm weather patterns outside. If you want to open a window to get some fresh air, it is better to leave your air conditioner on rather than turning it off. If the inside of the house gets hot and you have to turn the air conditioner back on then your air conditioner has to work harder to cool down your house and everything in it.