One of the main considerations when deciding on an air conditioning unit for a home is the unit’s size. “Size” in this instance doesn’t have to do with the amount of space taken up by the unit (even though that IS a consideration), but rather how much power it has when it comes to cooling capacity.

Choosing the right size AC unit very important. You want it to have enough cooling capability to maintain a comfortable temperature. Choosing one that is too small or too powerful bring with them their own unique sets of problems and those problems can be very serious. This is one reason why it is so vital that you let a professional handle the installation. Mistakes can lead to a system that doesn’t work correctly and will subsequently cost a considerable amount of money to put right.

What if the Unit is Too Small?
If the AC unit cannot provide a cooling capacity that is sufficient for the space, the temperature of that space will not be consistently comfortable. Cooling will be unevenly distributed leaving rooms further away from the unit with noticeable hot spots. The AC will then run for longer than it ought in its effort to make up for the lack of cooling ability. Systems that work that hard age quickly and break down more often. They also cause spikes in energy usage which leads to higher electric bills. A smaller system may mean a smaller initial investment, but it will cost more over time than would one suited for the space.

What if the Unit is Too Large?
While it may be more difficult to envision why a larger unit would pose a problem, turning it down is not a viable solution. If the unit is too large, it will begin “short-cycling.” In other words, it will cause the temperature in the nearest rooms to drop too rapidly making the unit shut down and restart more frequently. This has the same effect on the longevity of the unit as running too long. Parts wear quickly and other operational problems can arise. Short cycling also wastes energy since AC units draw the most power at start-up. Fewer start-ups means less draw and less energy consumption.

Short-cycling also creates hot spots by over-cooling in areas closest to the unit and tricking the thermostat into shutting the unit down before the entire space is cool.

Professional Sizing
In either case, when major problems occur, there is little that can be done by way of repair to solve them. The unit will need to be replaced.

You can avoid the expense and aggravation by simply hiring an experienced technician to size the unit. A trained and qualified installer will perform a heat load calculation to determine the exact cooling load necessary to keep your home comfortable. Once that is done, selecting the right unit size is easy and you will only have to pay one time for an ideal air conditioning unit that is properly installed.