A Buying Guide for Central Air Conditioning


Installing or replacing central air is a big commitment and investment in your home, and all the choices available can be overwhelming. We’ve put together a buying guide for central AC to help you make the most informed decision you can.

Types of Central Air Conditioning 

Split System

The split system is the most common design for central air conditioning. If your home has a split system, then ductwork is used to distribute the cooled air around your home.

The steps to cool your home are as follows:

  • • Your home is feeling a little warm (or downright hot!), and you adjust the thermostat. Your system turns on. (The thermostat will maintain your desired temperature once the house cools.)
  • • Refrigerant circulates between the outdoor condenser with compressor (the large box that sits outside of your home) and an indoor coil.
  • • The refrigerant cools and dehumidifies the air as a blower circulates the cooled air throughout your home using ducts.

A variation on the split system is the heat pump system, which functions as both an air conditioner and a heater.

Split Ductless Systems

Some homes cannot accommodate central air because there isn’t room to install ductwork. For those homes, a split ductless system is installed. The cooling effect feels like a central air system.

Like central air, a split ductless system has an outside condenser and compressor, but that is where the similarities end. Air handlers (indoor blower units) distribute the air and are mounted high on the wall. These handlers cool the individual room in which they are installed and are controlled with a remote. The outdoor and indoor elements of the split ductless system are connected by a conduit that encloses the refrigerant tubing, power cable, and condensate drain. The channel is hidden behind each air handler.

Important Factors When Choosing Central AC

Once you’ve confirmed that your home can accommodate central air conditioning, there are other factors to consider.


The larger your home is, the bigger your central air conditioning’s cooling capacity will need to be. AC size is calculated in British Thermal Units (BTUs) per hour or tons.


Home Size                                        Air Conditioner Size

600–1,000 square feet                    1.5 tons (18,000 BTUs)

1,000–1,500 square feet                 2 tons (24,000 BTUs)

1,500–2,000 square feet                 3 tons (36,000 BTUs)

2,000–2,500 square feet                 4 tons (48,000 BTUs)

2,500–3,300 square feet                 5 tons (60,000 BTUs)



Efficiency in an air conditioner equals how much cooling the unit produces for every watt of electricity. An air conditioner’s Seasonal Energy Efficiency Ratio (SEER) rating will signal whether a system is efficient or not. The higher the rating, the more efficient the cooling equipment is, and the lower your energy costs will be. You should purchase a unit with a SEER rating of 15 or greater.

Programmable Thermostats

Programmable thermostats are an easy way to reduce your energy costs. Learn more about ideal settings and thermostat use here.


Scheduling a routine HVAC system checkup before each season will keep your heating and cooling system running at peak efficiency and save you money on energy bills. Plus, identifying and fixing minor problems helps you avoid expensive repairs later on. It also validates the manufacturer’s warranty for your units with certified, twice-a-year service. Learn more about our Comfort Plan.

Upgrading an Existing Central Air System

Upgrading your central air? You may need a different size from your old system. Upgrades you’ve made to your home such as new windows, adding insulation, etc., can affect your HVAC size. However, if you have expanded your home, you may need a larger system. The good news is that modern systems are 20–40% more energy-efficient than past models.

When upgrading your central AC, you will need a load calculation from your contractor, which includes whether your ducts will need to be resized, insulated, sealed, or even replaced.


If you are installing a brand-new AC system, your contractor will need to calculate the size of the system you need. If ductwork for your heating already exists in your home, adding a central system can cost less. However, heating ducts may not be in the right location or the correct size for optimal cooling. To be sure that your old ducts will work in harmony with your new system, your contractor must check that ducts are the correct size and that there are enough supply registers to deliver cooled air. Undersized ductwork can waste energy and be noisy. Other ways to optimize your ducts:

Clean Your Ducts 

Having your ducts professionally cleaned results in better indoor air quality and an HVAC system that runs more efficiently with better airflow. It could also mean fewer colds and respiratory problems for your family and a decrease in your energy bills. If you are unable to have your ducts professional cleaned, then be sure to clean dirt and other debris from the condenser coils, change filters monthly, and check for blockages in the drainpipe. Also, be sure to keep any hedges or bushes that are close to the outside unit trimmed.

Seal and Insulate Ducts

It’s easy to recognize drafts coming in through a door or window, but a drafty door doesn’t have near the effect on your energy bill that an improperly sealed or insulated duct will. A leaky duct can waste 20–30% of the energy used to run your system. Yikes! Be sure to seal and insulate your ducts to save money and to stay cooler in the summer, and toasty in the winter.

Installation: Call on Stuart Pro! 

When looking for a company to install or replace a central AC, we hope that we are the first you call. We’ve worked for years to build and maintain a trustworthy reputation in our community. If you would like to investigate before making your final decision, here are the steps to take.

Ask Around

Talk to your neighbors, friends, and family. Whose work do they recommend? Visit competitor websites and look at online reviews. Then call and speak to the different businesses. Ask questions, get a quote, and get a feel for each company.

Background Checks

It may seem extreme, but people who work on your air conditioning system will be in your home. You want to be sure that they are reliable. Things to look and ask for:

  • • Verification of bonding and insurance
  • • Required contractor’s licenses
  • • Standing with the Better Business Bureau and consumer affairs office
  • • Certification with NATE – North American Technician Excellence
  • • Online reviews and feedback

Get It In Writing. 

When getting a bid, ask for a detailed analysis of cooling needs for each room in your home. Request a printout of all calculations, including ductwork design. It is important to get a document from each contractor so that you can compare what each is offering. If a bid is drastically lower than a competitor’s, it may be because something crucial isn’t included in the less expensive bid.