There are five types of air conditioner systems to consider. Which is right for you?
This guide to AC types explains each one including its pros and cons plus air conditioning system prices for each. We provide the best air conditioner brands for each type too.
- Types of Air Conditioner Systems
- Air Conditioner Systems
- Census Data on Air Conditioning
Types of Air Conditioner Systems
- Split system air conditioners and packaged units
- Mini split system air conditioners
- Geothermal split system air conditioners
- Room Air Conditioner (Window ACs, portable ACs, etc.)
- Evaporative Cooler
Air Conditioner Systems
This overview chart allows you a basic at-a-glance comparison of the best air conditioner systems to consider.
Sizes in BTU/h
Split System AC
18K to 60K
Good for Replacement
6K to 48K
Good for New Builds
Can Be Costly
36K to 120K
6K to 30K
Single Room Only
Dry Climates Only
Split System Air Conditioners
The standard split system AC remains the most common system used in American homes. This is partly because most homes have ductwork, so it makes sense to use a ducted system. Traditional air conditioning and heating system has much to offer in value and efficiency. Here is our comprehensive split system AC guide.
System Components and Operation
The outdoor unit, often called the air conditioner but technically the condensing unit, contains a compressor to pump refrigerant, a radiator-like coil to transfer heat and a fan to pull air through the coil to speed heat transfer.
The indoor unit is usually a furnace in climates where heat is needed. In very warm climates, an air handler might be used instead. The furnace or air handler contains a coil too. Refrigerant cycles between the outdoor and indoor coil through a set of refrigerant lines. Refrigerant is evaporated in the indoor coil, and it absorbs heat as it does. The refrigerant carries it outside where it is condensed from a vapor back into a liquid. It sheds heat in this process, and the heat radiates out of the coil.
Meanwhile, the indoor coil gets very cold as all that heat is removed. Humidity in the air condenses on the coil and is drained away, drying the air in the home. Drier air is more comfortable during AC months.
The air handler or furnace also contains a blower, a motor and wheel fan combo, that pulls in warm air, aka untreated air, and pushes out cooled or treated air. A thermostat controls the system.
Packaged air conditioning units and packaged gas/AC units use standard components, but they are housed outside in one large cabinet.
That’s a long explanation! Those are the basics of how most air conditioning works. There is less detail in the descriptions below.
Features and Options: Split system air conditioners come in three performance levels. Single-stage or 1-stage units run at full capacity all the time. They’re affordable, but offer less climate control, i.e., temperature balance and dehumidification. Two-stage or 2-stage units run at 65% (70% for some models) and 100%. They are the middle ground for efficiency, cost and climate control. Variable capacity or modulating or variable speed air conditioners have compressors that run at any capacity between 40% (25% for some models) and 100%. They cost the most, are the most efficient and provide the best climate control.
Systems sizes start at 1.5 tons, or 18,000 BTU/h to 5.0 tons, or 60,000 BTU/h. Btw, BTU/h is the amount of heat they remove per hour.
System Efficiency: 13 SEER to about 26 SEER. The upper end rises almost every year.
Pros and Cons: First the advantages. These can be affordable whole-house air conditioners. They give you lots of performance and feature options to suit your climate, budget and climate-control preferences. Repair parts are easily obtained, and repairs can usually be made in a day or two. The disadvantages are that they are not as efficient as geothermal air conditioners or the most efficient mini split systems. Because they use ductwork, their total efficiency can be hurt by duct leaks and non-insulated ductwork.
Comparison to Other Types: They are midrange in cost, as the chart shows. Of course, they require ductwork and deliver cooled air to the entire home.
System Cost: $2,600 to $10,000 installed. Factors are size, how many stages of cooling it offers and efficiency.
Top Brands: Identical brands owned by a parent company are grouped together – Trane/American Standard, Carrier/Bryant, Rheem/Ruud, Armstrong Air/Aire Ease, Lennox/Payne, Heil/Tempstar/Day & Night, York/Luxaire and Daikin/Amana/Goodman. Here are the brands research shows are the Best Air Conditioner Brands.
Best Use: If your home has ducts, then this will be the most cost-effective air conditioner type. If you’re building a home or addition, we recommend researching our Ductless Mini Split guide and getting cost estimates for both types.
Mini Split/Ductless Air Conditioners
The market for mini split systems is growing. They have a lot to offer in efficiency and climate control.
System Components and Operation
Like standard split systems, the condensing unit is outside. It can be set on the ground or roof or attached to the side of the home.
Instead of one indoor air handler, these systems have 1-8 indoor units. Each room or zone is served by an indoor unit, aka evaporator unit. They can be individually controlled. The indoor units have a blower. Some have oscillating louvers to evenly disburse the cooled air. Each has a drain line plus a power line and refrigerant line set that connects it to the condensing unit.
Features and Options: While AC-only split systems are available, most are heat pumps. They provide cooling and heating. All ductless air conditioners and heat pumps have variable capacity compressors that provide outstanding temperature balance and dehumidification. The indoor unit is often wall-mounted, but other locations for the unit are the ceiling, floor and inside existing ductwork – so they are hidden from view.
System Sizes: Condensing units range from as little as 6,000 BTU/h up to about 48,000 BTU/h. You can find a few larger units, but they are not common. Large homes typically use 2 or more condensing units, which is true if the system is a standard split AC system.
System Efficiency: The range is 14 SEER to 38 SEER. Most are 17-21 SEER.
Pros and Cons: The plusses of split system air conditioners and heat pumps is their efficiency, the fact they don’t require ductwork and their excellent climate control. Standard split system heat pumps don’t work well in freezing weather. The top ductless systems can draw enough heat to keep your home warm in sub-zero temperatures. There are a few disadvantages too. Each zone needs its own indoor unit. If your home has an open floor plan, then maybe one or two units will do. If rooms tend to be closed off, then you might need 4-6 or more indoor units. This leads to higher equipment and installation costs compared to standard split system, ducted air conditioners.
Comparison to Other Types: Ductless mini split air conditioners and heat pumps are more efficient than most standard split air conditioners, but that gap is closing quickly. They are versatile. You can use a mini split air conditioner or heat pump as a whole-house system, and they are ideal for additions, converted garages or attics or a part of the home that isn’t adequately served by the central AC system.
System Cost: $1,500-$15,000 or more. The smallest one-room ductless ACs are quite affordable. They have the advantage over a window unit or portable AC in efficiency, quiet operation and climate control.
Top Brands: Mitsubishi, Fujitsu, Gree, Samsung, Daikin, Pioneer, LG and MrCool. US brands like Carrier and Trane have begun making mini split systems. Some are rebranded systems from one of the companies already mentioned.
Best Use: If you’re building a home or commercial building or constructing an addition, we recommend getting prices on a mini split system. They are also ideal for converted space because the existing system probably won’t effectively cool the extra square footage.
Geothermal Split System Air Conditioners
Standard air conditioners disperse heat into the air. Geothermal heat pumps “dump” the heat into the ground or water, hence the term “geothermal.”
It’s much easier to transfer heat into earth or water that is 55-60 degrees instead of dispersing it into hot summer air is much easier. That’s why geothermal air conditioners, or more often heat pumps, are very efficient.
System Components and Operation
Indoor equipment is similar to standard and mini split systems. Refrigerant is used to collect and move heat from indoors outside and from outdoors inside.
Features and Options: Most units are either 2-stage or variable capacity models. Blowers are often variable speed. These features create excellent climate control and outstanding efficiency.
System Sizes: Systems start at about 2 tons, or 24,000 BTU/h. In geothermal lingo, that would be written 24MBH. Most models are offered up to about 5 tons, but many are produced in larger sizes up to 10 tons, or 120MBH.
System Efficiency: Geothermal heat pumps are rated in EER rather than SEER. The rating is slightly different, which is explained in this FAQ post.
Geothermal units range from about 25 EER to more than 50 EER.
Pros and Cons: The efficiency is tremendous. That is their chief advantage. There are several concerns to consider. They are far more expensive than split systems. And while some systems are more efficient, your energy cost savings might never offset the higher cost of equipment and installation– especially installation. Secondly, repairs to these systems can be expensive. There are good comments in our Geothermal Guide from homeowners that have had them installed. They give a clear picture of the pros and cons.
Comparison to Other Types: Efficiency is much higher; costs for equipment and repairs are higher.
System Cost: The smallest systems installed start at close to $10,000. Average cost is about $20,000. Prices have come down in recent years.
Top Brands: ClimateMaster, WaterFurnace, Carrier, GeoCool, Daikin/McQuay, Trane/American Standard.
Best Use: Climates with extreme heat or cold. In those regions, lowering energy costs is more crucial than in moderate climates where less air conditioning and heating is required.
Room Air Conditioners
Room air conditioners are window air conditioners, portable air conditioners and through-the-wall air conditioners (or simply wall air conditioners).
We have completed the Window AC Buying Guide and a library of reviews of top window air conditioners in each size class.
System Components and Operation
Everyone is familiar with window air conditioners. An internal coil and the radiator-style outdoor coil are connected with refrigerant lines. Heat is absorbed indoors and dumped out the back along with moisture.
A wall AC operates the same. Most through-the-wall ACs have a steel sleeve that fits into the hole and allows for sliding the AC in and out seasonally.
A portable AC is fully inside the house. Heat and humidity are vented through a flexible vent hose and window kit.
Features and Options: Most are single-stage. They have low/medium/high cooling settings and fan speeds. Most have timers, remotes and digital controls, but a few window ACs are still made with rotary controls.
Sizes: Portable ACs top out at 14,000 BTU/h currently. Window units can be as large as 30,000 BTU/h. A few are larger.
System Efficiency: EER ratings for window and wall air conditioners range from about 9 to 15. Portable ACs are less efficient – about half as efficient. We discuss why this is true in our Portable AC Guide, which we recommend reading before you choose a portable AC vs Window AC.
Pros and Cons: The advantages are cost well below central air conditioning and the option to move a window or portable unit to a different room. Plus, you’re only cooling the room you are using, not wasting energy and cost cooling the whole house. The disadvantages are lower efficiency, especially portable air conditioners, cooling only one room if you want air conditioning everywhere and the higher noise levels since the compressor is inside or at best in the wall.
Comparison to Other Types: Single room air conditioning vs whole house AC, much lower prices.
System Cost: They start at less than $200 and range to about $600 for large units with lots of features. Models that are heat pumps can range to $1,000 or more.
Top Brands: LG, Frigidaire, Friedrich, GE, Honeywell, Haier, Danby, Ivation.
Best Use: Most are used in mild climates where just a little air conditioning is needed. Also, in centrally air conditioned homes, they cool rooms that don’t get enough of the cool air. They are also popular for converted attic and garage space.
Evaporation is the key to all types of air conditioning. Most of the time, the evaporation occurs in a closed system – In AC coils. Evaporative coolers use evaporation in open air to cool it. These units are also called swamp coolers.
System Components and Operation
The essentials are a water tank, cooling pad or pads and a fan to move the air.
Water from the tank wets the highly absorbent pad. The fan forces air through the pad, causing moisture to evaporate. Water has the capacity to take a lot of heat with it when it evaporates. The air passing through the pad is cooled by this evaporation.
Features and Options: Indoor units and outdoor evaporative coolers are available. Outdoor models are larger with more powerful fans. Most have multiple fan speed settings. Some have connections for a hose, so you don’t have to fill them. Most also have low-water alerts for using a tank rather than a hose.
System Efficiency: There are no ratings. What does matter is how humid the air is. Evaporative cooling works best when the air is dry – the faster evaporation happens, the more heat is taken with it. In humid climates, these coolers won’t help much.
Pros and Cons: The cost of the equipment can be lower than a portable or window AC. In arid climates, they can be quite effective. The disadvantage is that a swamp cooler is ineffective in high humidity.
Comparison to Other Types: They are greener, since no refrigerant is involved. They use about as much energy as other types.
System Cost: Prices for residential models start at about $50 for personal-size units. Most cost $125-$250, but several cost above $500.
Top Brands: Honeywell, Hessaire, Cool-Space and Luma. There are reviews and buying tips in our Best Evaporative Cooler guide.
Best Use: A swamp cooler is ideal for cheap cooling in a small space in arid conditions.
Census Data on Air Conditioning
The most recent Census Bureau information on air conditioning comes from a 2017 survey of 121,560 households. Here’s what the data shows.
How Many US Households Have Air Conditioning?
9.6% had no air conditioning of any kind.
90.4% had at least one air conditioning unit.
What Type Air Conditioners Are Used in US Households?
Of the 90.4% that had at least one AC unit:
69.5% had central air conditioning.
20.9% had room air conditioning – a window, portable or wall AC.
9.6% had another, unspecified type of air conditioning such as an evaporative cooler.
How Many Room Air Conditioners Do Households Without Central AC Have?
Of the 20.9% of households that use room air conditioning as their primary AC:
42.4% had one room AC.
32.8% had two room ACs.
15.9% had three room ACs.
6.5% had four room ACs.
2.4% had five to seven room ACs.
Do Homes with Central AC Use Other Types Too?
Of the 69.5% of households with central air conditioning as their primary AC:
15.5% had a second AC.
84.5% did not.
What Kind of Secondary AC Do Most Households Have?
Of the 15.5% of households with central AC that also used another air conditioner:
59.3% had a second central air system. This is often the case in large homes. Part of the home is served by one unit, the other part by the second.
40.7% had one or more room air conditioners to supplement their central AC. These room ACs are often used in rooms facing west or south and/or in rooms far from the air handler that aren’t adequately cooled by central air conditioning.