A grossly undersized air conditioner just can not keep up on those genially hot days. Oversized units can be even worse, however, because they cool in abbreviated, energy-saving bursts, then shut down. During which, the interior humidity level increases and the air begins to feel clammy. Properly conditioned summer air, remember, is drier, and also cooler. If that portable or window air conditioner unit just is not keeping up with your cooling needs, a central air conditioning system is the answer. How big of an unit depends on the area and layout of your home.
When a contractor figures out what your house's heat gains are, an installer will check the furnace blower and ducting to determine if they can handle the heavier cooled air. While the plenum is being inspected, ask if it can be changed easily to accept an electronic air cleaner, a power humidifier, or both. Even if you can not afford these items now, allowing for them will save on installation costs later.
You also should consider installing a zoned system. Such a system could save on energy costs by keeping daytime temps higher in empty rooms.
Two-speed condensing units offer another way to lower operating costs, matching a system's capacity to its needs. Lights on the thermostat let you know whether a two-speed unit is running at high or low speed, giving you a chance to raise the temperature setting and reduce demand when you choose.
Natural-gas-powered systems are also available. Installation costs will be greater than for an electric air-conditioner, but you may recover the difference, and more, in lower operating costs, less maintenance, and longer life. This depends on your energy costs.
Finally, do not be surprised to find a wide range of prices for equipment with similar Btu capacities. Quality differences account for most of this variance. Some components are guaranteed for five years, other for ten.
So how much will a quality air conditioner system cost, installed? Local prices will of course vary a great deal but assuming a 1500 square foot house, 15 years old with all ductwork in place, expect to pay between $ 1500 to $ 2000 to replace an old 3-ton air conditioner with a new energy efficient SEER 10 setup . If you currently have no air conditioner unit in place, expect to pay between $ 5000 to $ 7000 for a complete setup including the ductwork. Not cheap by any means but in certain areas, it is a necessary expence.
