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Central Air Conditioners

Efficiently Keeping Your Whole House Cold.

Central Air Conditioners are essentially split system air conditioners accompanied by ductwork. This means that the noisier compressor and heat–shedding condenser components are installed outside and connected by refrigeration lines to the evaporator and blower unit installed inside.

This, in turn, is connected to a system of insulated ductwork which distributes the cool air produced by the evaporator.

The standard warranty you should look for should have a 10–year warranty for the compressor and a 5 year warranty on the rest of the unit. A contractor will generally do this type of installation for you, as it will likely require a permit. The Department of Energy recommends that you ensure your contractor is bonded to ensure the performance promised, insured against liability, and certified by one of the two national programs (Air Conditioning Contractors of America or North American Technical Excellence).

Central air conditioner power is measured in tons of cooling. One ton of refrigeration is equal to 12,000 BTUs and is the amount of heat energy required to melt on ton of ice at 32°F in 24 hours. Units generally range between 1 ton and 5 tons of cooling capacity. The greater the capacity, the greater the cost. Remember that this type of unit may also function as a heat pump. If you are looking for this functionality and live in an area with mild winters, this may prove to be a great way to take care of all your comfort needs.

Seasonal Energy Efficiency Ratings (SEER) for Central Air Conditioners may have be as low as 13 and as high as 23! Be aware these higher–efficiency systems can be as much as $2,500 more expensive than their lower–efficiency counterparts, though they cost significantly less to operate and will pay for their upfront premiums and more over time. They may also be eligible for a tax credit if you live in the United States. These higher efficiencies are achieved by utilizing by larger heat–exchange surfaces dual (also known as 2–stage) compressors. In a dual compressor setup, a smaller compressor runs most of the time and usually exclusively on milder days. On hotter days, a second compressor switched on to help carry the load. This means that a single, more powerful compressor is not being cycled on and off constantly. As mentioned in our BTU sizing section, longer cooling cycles offer less noisy and more efficient operation as well as better humidity reduction.

It is worth mentioning that there are predominantly two types of compressors available in central air conditioners: scroll and reciprocating. A reciprocating compressor operates in very much the same fashion as a piston in a car. A scroll compressor is a bit more complex and uses one fixed scroll opposed to one oscillating scroll to trap refrigerant vapor in the spaces of the outermost portions. The oscillation of the system conveys these vapor–filled cavities to the ever–smaller center of the scroll where they reach the desired compression before exiting the system. A good video to help visualize this can be found here. The general assumption is that the scroll compressors are somewhat quieter and more mechanically resilient and thereby requiring less maintenance while the reciprocating compressors are much cheaper for manufacturers to produce and consumers to purchase. The RSES (Refrigeration Service Engineers Society) journal recently did a study comparing the efficiencies of each system and concluded that while both are quite good, reciprocating compressors are slightly more efficient in systems with 1 to 3 tons of cooling while scroll compressors are more efficient where 3.5 to 5 tons of cooling is required. At the end of the day, you need not trouble yourself with this both methodologies have excellent quality and reliability ratings that will often outlast their warranties for years to come.

Newer central air conditioners also use more efficient Puron (R–410A) refrigerant instead of ozone depleting Freon (R–22) which is being phased out. Buyers should at the very least look for a unit that utilizes Puron, as maintenance costs for Freon-driven units will certainly rise over time as it becomes more scarce.

Buyers should keep in mind the location where a unit is to be installed when making a purchase, as obstructed airflow can reduce efficiency. Vibration dampening compressor covers and rubber fittings can reduce system noise when in full operation. Central Air Conditioners should also have some sort of rust–proofing in the base pan and body panels. If a unit does not have full body panelling, look for heavy–duty wire guards and insulation to protect the exterior unit against the elements and incidental impacts with gardening equipment, garbage men or rogue sporting equipment.

If you are doing a replacement, you need to make sure your contractor does not simply look at your existing central air conditioner unit and sell you another with the same BTU output. These types of units have become much more efficient over the years, as has insulation for walls, windows and ceilings. Make sure the contractor does a Manual J calculation that takes all these factors into consideration to determine the appropriate capacity or you could end up with an oversized system. You may not need as many BTUs as you did in the past! By the same token, a Manual D calculation should be done by the contractor to ensure properly sized ductwork and efficient layout design. provides a thorough discussion of the importance of Manual J and Manual D calculations when planning an air conditioning installation for your home.

If you are retrofitting a new central air conditioning system into an existing structure, there are many possible architectural obstacles that may need to be considered. For example, if your home has a lot of masonry, this may prevent ductwork from being routed through the walls and could increase the total installed cost of the system. One option available to consumers in this situation is to purchase a mini–split ductless air conditioning system. These systems are similar to a central air system in that the compressor and the condenser are installed outside, but this single unit will service the needs of several single–room evaporators installed through–the–wall inside. These systems generally rare to find in the United States and while cheaper than a central air unit to purchase, can be expensive to install and require more maintenance due to the increased number of components.

Central Air Conditioners offer good operating efficiency and low–noise but at a high installed cost even in the most ideal situations. Each system has its upsides, downsides, capabilities and restrictions and it may be worthwhile to weigh the value of an alternative system such as a high capacity window or portable air conditioning units and see what is most cost appropriate for your circumstances.

Central Air Conditioner Comparison Charts

To quickly and easily compare the specifications, warranties and features of available central air conditioners, please refer to our Central Air Conditioner Comparison Charts section below:

Amana - Cooling Homes since the 1950's

Carrier - The Largest Air Conditioner Producer in the World

Goodman - Inexpensive Units Backed by a Winning Warranty

Lennox - Leading the Industry in Innovation and Efficiency

Trane - Offering one of the Widest Selection of Units with Features to Fit Your Needs

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Central Air Conditioner Comparison Charts

Amana - Cooling Homes since the 1950's

Carrier - The Largest Air Conditioner Producer in the World

Goodman - Inexpensive Units Backed by a Winning Warranty

Lennox - Leading the Industry in Innovation and Efficiency

Trane - Offering one of the Widest Selection of Units with Features to Fit Your Needs

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The Quietest Air Conditioners - No more yelling when the compressor kicks on!

Lennox Air Conditioners - Leading the Industry in Innovation and Efficiency

Small Air Conditioners - Small but strong

Carrier Air Conditioners - The Largest Air Conditioner Producer in the World

Trane Air Conditioners - All about Trane Central Air Conditioners - Offering one of the Widest Selection of Units

Window Air Conditioners - For Standard or Casement Windows

Amana Air Conditioners - Demand an Amana

Portable Air Conditioners - Take your Air Conditioning with you!

Air Conditioner Sizing - What's the right Size and BTU output I need?

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