An oversized air conditioning unit comes with several negative side effects. Improper sizing can result in high electric bills, excess humidity and inconsistent temperatures in your home. It’s important to make sure your air conditioner is neither too big nor too small when installing a new unit in your home. Here’s how to make sure your AC is the perfect fit.

Signs Your Air Conditioner Is Too Big

1. Short Cycling

Short cycling prevents your home from being able to effectively heat and cool. This leads to increased utility bills since your air conditioner is constantly having to start and stop. Short cycling also decreases the life expectancy of your air conditioner since the motor is being used more frequently to start up the system.

2. Inadequate Dehumidification

When your air conditioner is too big for your home it causes inadequate air flow. Temperatures drop rapidly which seems like a positive when in reality this only causes a small amount of air to move across the coil in efforts to extract the moisture from the air before being emitted again. This will result in a cold house, but a humid, swamp-like environment that only opens up the opportunity for mold and fungus to grow around the house.

3. Inconsistent Temperatures

Your AC has a sensor that stops air from cooling as soon as the temperature on your thermostat is reached. Since an oversized air conditioner reaches that temperature faster than it should, the rest of your home may not have gotten the same amount of cool air as the area surrounding the sensor.

How Do You Measure the Size of an Air Conditioner?

There are multiple factors to consider when calculating what size AC is suitable for your home. Some of these factors include the length, width, height and insulation condition of your home (you can find this information on a property tax statement). Air conditioner size is measured in the British Thermal Unit (BTU) as a unit of energy, measured in tons per hour. While most air conditioners range between one and five tons, the formula to find the perfect fit is easy once you understand the science behind it. One ton is the ability of your air conditioner to cool 12,000 BTUs in an hour which basically translates to: a 1-ton air conditioner can cool 12,000 pounds of water by one degree every hour.

Here is a chart that will provide you with a guide to the average air conditioner size in reference to BTU.


If that’s just too much information for you, then take advantage of this BTU calculator that calculates the amount of BTUs you will need in order to cool your home.

Troubleshooting the Size of Your Air Conditioner

Air conditioning runtime on a hot day will say a lot about the size of your air conditioner. If it is shutting off after 10-15 minutes and then starting up again shortly after to run for another 10-15 minutes then you have a problem. The average run time of your air conditioner on a hot day to properly dehumidify the air and distribute cool air evenly throughout your home should be about 45 minutes.

Expert AC Installation Means No Oversized Air Conditioner

Hiring a qualified AC professional you can trust plays a big role in the air quality and comfort of your home, which is why the technicians at Blair’s Air are the first choice for all your HVAC needs in the Tampa Bay area. Contact Blair’s Air today for your FREE service call!

Call 727-592-8479 to schedule your appointment.