by Jeff Parsons

Created on: October 11, 2010   Last Updated: October 26, 2010

When people think about air conditioning, they tend to remember the old windowsill units, or, modern central air conditioning. Respectively, these units will only cool one room, or, every room at the same temperature. Alternatively, an air conditioning split system will allow you to cool many rooms individually.

All air conditioners use a fan to draw air from your house, push it across a cold evaporator and then send it back into your house. Refrigerant fluid in the evaporator absorbs the heat and sends it to a condenser, which, in turn, uses a radiator to cool the fluid off before it gets sent back to the evaporator.

A room air conditioner is the typical windowsill unit which provides cooling to one room. The evaporator and condenser are located next to each other, so they decrease each other’s performance – there’s only so much cooling that the cooling unit can do next to the hot evaporator. They can also be quite noisy. On the plus side, these units are inexpensive and easy to install.   

A central air conditioner is usually located within one cabinet, but it does have more separation between the evaporator and condenser systems. It uses ducts, usually sheet metal tubes, to send circulate the air. They are more efficient than room air conditioners, but in the length of the ductwork, the air will heat up before it gets to your rooms. They also have only one temperature setting on the thermostat. That is, you can’t have individual settings for each room. As a result, some rooms may be colder or hotter than others.

An air conditioner split is a system that completely separates the evaporator and cooling system. If an air conditioner split is used, the cooling system is located outside of the house, making it quieter and more efficient. The main advantage is that many rooms can be individually cooled using just one cooling system. The ability to set the temperature for each room can provide a great savings in the long run.

An air conditioner split may also take on a more compact form – one that doesn’t need any ductwork. Hotels often use this type of air conditioning, called ductless split air conditioning, where the evaporator is located inside the room and the cooling system is located outside the room, both interconnected by insulated tubing which is much more efficient than ductwork. Many evaporators, or rooms, can also use the same cooling system!  One very popular option, called a ductless mini split unit, is very compact - it opens up a great variety of design options for houses that have space limitations.  

To help compare air conditioning systems, the EPA and DOE have created the Seasonal Energy Efficiency Rating (SEER) to describe a system’s efficiency. The SEER number is the system’s cooling capability divided by the cost to operate it. So, a system with a higher SEER is more efficient. To put this in perspective, a window unit may have a SEER of 10 and a ductless split air conditioning system may have a SEER of 25. Of course, a higher efficiency product costs more. Also, if you don’t have much demand placed on your cooling system, then you won’t need the best model. A good service technician should able to help you decide what’s best for your house.

All in all, a split air conditioning system works best in most cases, even more so if it’s ductless or compact enough to suit your needs, such as a mini-split.

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