The basics of air conditioning
With the start of summer and the onset of warmer weather, a central air conditioner could start to look like more of a necessity than a luxury. All air conditioners -- including portable air conditioners, room air conditioners and central air conditioners -- work basically the same way as your refrigerator: They pump heat from one area (in this case, your home's interior) and transfer it to another (the outdoors). An air conditioning system contains several parts:
- The evaporator is a winding coil, usually made of copper, which draws out warm air from indoors.
- The condenser is a separate coil that releases the collected heat outside. This coil is surrounded by aluminum fins to disperse the heat.
- The refrigerant is a liquid that transfers heat from the evaporator to the condenser. It evaporates in the indoor coil, pulling heat out of the air, and turns back to a liquid in the condenser, releasing its heat outdoors.
- The compressor is a pump that forces the refrigerant through this network of tubing and fins. This is the part of the system that uses electricity.
In a room air conditioner or a portable air conditioner (which we cover in separate reports), all these parts are contained in one compact unit that sits in a window; can be installed permanently in a wall; or, in the case of portable air conditioners, sits on the floor and is vented to the outside via flexible connecting hoses. Individually, these units are much cheaper than a central air conditioning system and are easy to install. However, they only have enough power to cool a single room and if you want to cool multiple areas, costs can mount up. We cover room and portable air conditioners in their own reports.
If you need to cool an entire home, a central air conditioner is much more efficient than having a window or portable air conditioner in each room. And even though room-sized air conditioners are quieter than ever, a central air unit is quieter still (at least as far as occupants inside your house are concerned). Central air conditioners are also easy to use, but they are much larger and more complicated to install.
Unlike a room air conditioner, which is an easy do-it-yourself task, a central air conditioner must be installed professionally -- and as we'll discuss in the Buying Guide section of this report, the quality of that installation can go a long way toward determining how satisfied you are with your choice of central air systems. However, a quality installation can add thousands of dollars to the sticker price of the system itself, though how much can vary greatly. Among the factors to consider is whether or not your home already has forced-air heat. If it does, the ductwork needed to distribute cold air from a central air conditioner is almost certainly already in place; if not, it will have to be added -- and that, of course, increases the cost and complexity of the project. If you're also thinking of replacing your furnace, we cover those in a separate report, recommending the top choices in that category as well.
Finding the best central air conditioners
In general, consumer publications do not test central air conditioners. Experts generally agree that proper installation and maintenance are at least as important to the performance of an air conditioning system as the unit itself, so testing in a lab would provide little useful information about real-world performance. However, we did find a few sites run by HVAC professionals, such as WebHVAC.com and TecHomeBuilder.com that recommend specific air conditioning brands based on factors such as features, efficiency and warranty. ConsumerReports.org doesn't rate central air conditioners, but does rate the reliability of the top brands based on a large survey of its members. FurnaceCompare.com has the largest selection of user reviews that we spotted. Together, these and other sources enabled us to choose top central air conditioners that combine efficiency, durability, strong warranties and quiet operation.