Central Air Conditioning

An entire home or building can be cooled consistently and comfortably by a central air conditioning system. The main components of such a system are an outdoor compressor unit and an indoor air handler. These two units work in concert to draw in warm, humid air from inside the building, extract the heat (and a great deal of moisture), and return cooled, dehumidified air back into the building. Central air conditioning is more efficient than using several window-mounted or portable units placed in various rooms. Moreover, cooling the whole space from a single, centralized system allows for better control of temperature and humidity throughout all the rooms.

Under typical usage conditions, the bulk of HVAC professionals agree that you should change the filter in your central air conditioning system every three months. If your dwelling houses pets, has a lot of people living in it, or is in an area where there's a lot of dust (and who doesn't have at least some of that!), then you're going to want to change your filter more often—probably every one or two months, or even every two weeks if your system uses high-MERV filters.

With careful maintenance and attention, the average central air conditioning system can last 15 to 20 years. Factors that can impact the longevity of an air conditioning unit include local climate, how often the system is used, the quality of its installation, and the sorts of maintenance practices generally followed. Potential longevity notwithstanding, when a system hits the 10- to 15-year mark, it's ripe for consideration as a replacement candidate, both for reasons of energy efficiency and reliable service during the hottest months of the year.

The installation price of a central air conditioning system can differ greatly from one situation to another, often falling between $3,500 and $7,500 for a centrally located air conditioning unit in a space about our size. The estimates we obtained had a lot of variability, and they're fixed by a fundamental ratio of the estimate's size to either a size or an efficiency number. In our case, we compared the air conditioning estimate to our square footage and to how efficient we hoped the unit would be. And so we got back a kind of a number that is operating on a reasonable explanation for how much central air conditioning should cost to install in our home.

The consistent efficiency of your air conditioning system largely depends on its annual upkeep; that's the starting point. The next is regular, seasonal filter changes. From there, you can troubleshoot a few common central air problems, which don't necessarily mean that your system needs repair. The first thing to check is insulation. After that, you should be looking around for air leaks. If there are any, your system's going to have to cool your house to a temperature even lower than the desired one, which is a waste. If you insulate well and seal air leaks, your system won't be working against you. Consequently, if you do these several things, your system will have an excellent chance of working efficiently.

There are several telling indicators that your central air conditioning system is in need of repairs. These include, but are not limited to: hearing unusual sounds—grinding, squealing, or something else odd you're not used to hearing—coming from the unit; feeling a noticeably weak airflow from the vents; and being hit with the surprising realization that your energy bills have jumped up way more than you expected. Other potential red flags include frequent cycling, funny smells, and the appearance of actual moisture or ice on the unit itself (not in front of it where a puddle might form from condensation when the heat is on). If you notice any of these signs, get in touch with an A/C pro ASAP.

Central air conditioning systems cool effectively but can have difficulty in very humid conditions. Heat pumps are capable of both cooling and heating. They are typically more energy-efficient than either central air conditioning or electric resistance heating. They can, however, be less efficient than natural gas furnaces. Central air conditioning systems typically work with a separate furnace in the winter. When the choice is between central air and a heat pump, the decision often hinges on whether your house's design makes it easy to use the ducts a heat pump requires.

Determining the proper size for a central air conditioning system begins with figuring the basic dimensions of the house to be cooled. This means not only the square footage but also the height of the ceilings, since these figures all contribute to the total volume of space that the A/C must chill. It is also vitally important to take into account the quality and type of insulation that the house has. Poorly insulated homes must have a much larger A/C unit than well-insulated homes, which can "hold" the cold better. Finally, local climate conditions must be considered. An A/C that works well in a dry, hot climate may need to be somewhat larger (and should definitely be different in kind) to cool equally well in a hot, humid climate.

If you want to lower your energy expenses, think about installing a thermostat you can program.