Central Air Conditioning Buying Guide (2020)
What Factors Should You Consider When Buying a Central Air Conditioner?75% of home in the US use air conditioning, and 75% of those homes have central air. Central air conditioners are popular because they deliver more cooling power per square foot for the money than regular air conditioners. Whether you are purchasing a central air conditioner for the first time, or replacing your current AC unit, this guide is deigned to help you make an educated buying decision. Air conditioning units usually last between 10 and 15 years, as opposed to furnaces, which generally last between 20 and 30 years. There are many factors to consider when buying a central air conditioner – size, price, energy efficiency, warranty, ongoing maintenance, and energy rebates, to name a few.
Table of Contents
- How Do Central Air Conditioners Work?
- How the Indoor Air is Cooled
- Central Air vs Heat Pumps – What’s the Difference?
- Types of Central Air Conditioning Systems
- Considerations for Buying a Central Air Conditioning System
- SEER Rating
- Size of the Air Conditioning Unit in BTU
- Consider the Local Climate
- Pricing and Efficiency
- Programmable Thermostats
- Rebates and Financial Incentives
- Choosing a HVAC Contractor
- Maintaining Your Central Air Conditioner
- Final Thoughts
How Do Central Air Conditioners Work?
There are a few components that all central air conditioners have: a condenser unit (with a compressor), and air-handling unit with a blower, an evaporator, and a system for exchanging hot indoor air with chilled air. Supply and return openings move cool air from the air conditioner through the home. As the air becomes warmer indoors, the warm air flows back into the central air conditioner. The condenser unit usually sits outside on a concrete slab, or on the roof, and contains the condenser and compressor. In packaged central air conditioners, the evaporator may also be placed in the condenser unit. In split systems, and non-packaged central air conditioning units, the evaporator is indoors. Ductwork or air handling lines distribute cooled air to the different rooms in the house.
How the Indoor Air is CooledIn the evaporator unit, usually placed indoors, arm air from inside the house passes through an intake with an air filter. This air passes over cooling coils which remove heat and humidity from the air using refrigerant. A fan blower, placed over the evaporator, disperses the cooled air inside the house. Meanwhile, in the outside condenser unit, in the condenser unit, heat is transferred from coils to the outside. A compressor moves refrigerant between the evaporator and condenser to chill the indoor air. A fan releases warm air to the outdoor air. This is all a complex way to say that indoor heat is transferred to the outside. Here is a PDF and infographic that explains in detail how this process works.
Central Air vs Heat Pumps – What’s the Difference?A heat pump differs from a central air conditioner in one way. Heat pumps are essentially central air units that can be reversed in the winter to move heat indoors, instead of extracting heat from the home and moving it outdoors. A heat pump has a valve that reverses the flow of refrigerant, allowing the unit to either heat or cool the home. Heat pumps extract heat from the outdoor air, moving it into the house. In colder climates, there comes a point where the heat from the outside air is insufficient to heat the indoor home, so a backup heat source, like a furnace, is necessary.
Types of Central Air Conditioning Systems
There are two main types of central air conditioners, packaged and split-system.
Packaged Central Air Conditioners.
In a packaged central air conditioner, the condenser, compressor, and evaporator are usually housed together in an outdoor unit. The cooled air is usually circulated through the home using ductwork. The advantage of packaged air conditioners is they provide even cooling throughout the house.
Split -System Air Conditioners.
Split systems usually have the condenser and compressor in an outside unit. An indoor unit is oftentimes connected to a heat pump or furnace. The evaporator coil is usually contained in the cabinet or supply air duct of the furnace or heat pump. The indoor unit is usually mounted to the wall in each room. One main advantage of ductless split-systems is you can cool specific rooms. Split-systems cost a bit more than packaged air conditioning units. They are a good option for homes that do not have existing ductwork. Split-systems and mini-splits also work well in all climates.