Air conditioning is an essential part of modern homes, especially during hot summer months. Since its invention by Willis Carrier in 1902, air conditioning technology has evolved significantly, which means there are more options than ever for homeowners. Today’s systems not only cool the air but also dehumidify it. This guide will explore the basics of air conditioning, different types of systems, and how to choose and maintain the right AC for your home.
How Does Air Conditioning Work?
Air conditioners use fans to move interior air over a cold surface, usually comprised of grids or “coils” of copper or aluminum tubing. As the coils chill the air, its moisture condenses on the coils and is drained away.
The coils are chilled by a refrigerant that’s pumped by a compressor through insulated lines to a condenser located outside. Refrigerants are liquids with a low boiling point, or the temperature at which the refrigerant turns from a liquid to a gas. In air conditioners the phase change happens at the coils, cooling them and removing heat from the inside air.
After leaving the coils, the refrigerant moves to the condenser where the pressure from the compressor changes it from a gas back to a liquid.
This second phase change makes the refrigerant give up the heat it gains from the inside air. After passing through the condenser, the refrigerant once again makes its way to the coil. Heat pumps provide winter heat in exactly the same way as air conditioners remove it in the summer, except the refrigerant flow is reversed. Learn more about the differences between a heat pump and AC.
The Cooling Process
The cooling process in an air conditioner involves several steps:
- Warm air from the room is drawn into the system
- The air passes over cold evaporator coils, which absorb heat
- Moisture in the air condenses on the coils and is drained away
- The cooled, dehumidified air is circulated back into the room
- The absorbed heat is transferred outside through the condenser unit
What Are the Key Components of an AC System?
An air conditioning system consists of several crucial components:
- Evaporator: Contains cold coils that absorb heat from indoor air
- Compressor: Pressurizes the refrigerant and moves it through the system
- Condenser: Releases the absorbed heat to the outside air
- Expansion valve: Regulates the flow of refrigerant
- Refrigerant: The substance that changes from liquid to gas and back, facilitating heat transfer
What Types of Home Air Conditioning Systems Are Available?
There are several types of air conditioning systems available for homes, each with its own advantages and best-use scenarios.
Central Air Conditioning
Central air conditioning is the most common type in modern homes. It uses a network of ducts to distribute cooled air throughout the house. The main components are typically split between an indoor air handler and an outdoor condenser unit.
Pros of Central Air
- Cools the entire house efficiently
- Can be integrated with existing heating ductwork
- Provides consistent temperature throughout the home
Cons of Central Air
- Requires ductwork, which can be expensive to install in older homes
- Maybe less energy-efficient if ducts are leaky or poorly insulated
Most new homes are built with central air conditioning. The same ducts used to heat the house in the winter carry cool air in the summer. The cooling coils might be near an air handler (large fans in the ductwork that move air) in the attic or in the basement, or in both places.
If you’re having a new system installed or an old condenser replaced, insist that your contractor do a “Manual J” calculation. A Manual-J calculation evaluates the size of the house, its insulation, solar heat gain from the windows, and air leakage. It’s the only way to be sure your condenser is properly sized. Too small a condenser won’t cool adequately, and too large a one won’t dehumidify well.
Mini-Splits
Ductless mini-split systems have gained popularity in recent years, especially for homes without existing ductwork. These systems consist of an outdoor compressor unit connected to one or more indoor air handlers.
Pros of Mini-Split
- No ductwork required
- Allows for zone cooling
- Often more energy-efficient than central air systems
Cons of Mini-Split
- Higher upfront cost compared to window units
- Requires professional installation
A mini-split is a small central air system. Many also function as heat pumps. Depending on the cooling needs of the house, the best ductless mini-split AC will have one or more wall-mounted heads that circulate air. Ducted mini-split systems have small sections of duct to move air between rooms.
With their reputation for high efficiency, mini-splits have become a popular way to retrofit air conditioning in older houses, and as the prime heat and cooling source in well-insulated new homes. As with central air, be sure your contractor does a Manual J calculation to properly size a mini-split.
PTAC Systems
Packaged Terminal Air Conditioner (PTAC) systems are commonly found in hotels but can also be used in residential settings. These units are installed through an exterior wall and provide both heating and cooling.
Pros of PTAC Systems
- All-in-one heating and cooling solution
- Good for individual room control
- No ductwork required
Cons of PTAC Systems
- Limited aesthetic appeal
- May not be suitable for whole-house cooling
Window AC Units
Window air conditioners are self-contained units that fit into a window opening. They’re a popular choice for cooling single rooms or small apartments.
Pros of Window Units
- Affordable and easy to install
- No permanent modifications to the home required
- Can be removed and stored during cooler months
Cons of Window Units
- Limited cooling capacity
- Can be noisy
- May block natural light and views
Held in place by the upper sash of a double-hung window, the main virtue of a window air conditioner is that it’s cheap to buy. In heating climates, you’ll want to take them in every winter, otherwise, they can leak a tremendous amount of air.
Similar to window units are through-the-wall air conditioners. The main difference is that these units fit inside a sleeve that’s installed in the wall and they stay in place year-round.
Portable Air Conditioners
Portable air conditioners are freestanding units that can be moved from room to room. They typically vent hot air through a window using a flexible hose.
Pros of Portable ACs
- Can be moved as needed
- No permanent installation required
- Good for renters or temporary cooling needs
Cons of Portable ACs
- Less efficient than other types of AC
- Can be noisy
- Takes up floor space
How Do You Choose the Right AC System for Your Home?
Selecting the appropriate air conditioning system for your home involves considering various factors to ensure optimal comfort and efficiency.
Factors To Consider When Choosing an AC System
When choosing an AC system, keep these factors in mind:
- Home size and layout
- Existing ductwork (if any)
- Climate and average temperatures
- Budget for installation and operation
- Energy efficiency preferences
Energy Efficiency Ratings Explained
Energy efficiency is a critical factor in choosing an AC system. The main efficiency ratings to consider are:
- SEER (Seasonal Energy Efficiency Ratio): Measures cooling output relative to energy consumption. Higher SEER ratings indicate greater efficiency.
- EER (Energy Efficiency Ratio): Similar to SEER but measures efficiency at a constant temperature.
- ENERGY STAR certification: Indicates that the unit meets strict energy efficiency guidelines set by the U. S. Environmental Protection Agency and the Department of Energy.
As of 2023, new minimum SEER standards require ratings of 14 in northern states and 15 in southern states for most residential AC systems.
How Do You Maintain Your Air Conditioning Unit?
Proper installation and regular maintenance help improve the longevity and efficiency of your air conditioning system.
Regular Maintenance Tips
To keep your AC system running efficiently, follow these maintenance tips:
- Change or clean air filters monthly during peak usage
- Keep the outdoor unit clear of debris and vegetation
- Clean evaporator and condenser coils annually
- Check and clean condensate drains to prevent clogs
- Schedule professional maintenance at least once a year
Professional vs. DIY Installation
While some homeowners may be tempted to install their AC system themselves, professional installation is generally recommended for several reasons:
- Ensures proper sizing and installation
- Maintains manufacturer warranty
- Complies with local building codes
- Reduces the risk of system inefficiencies or failures
DIY installation may be feasible for window units or portable ACs, but central air and mini-split systems should always be installed by professionals.
How To Troubleshoot Common AC Problems
Understanding common AC issues can help you identify problems early and potentially avoid costly repairs.
Identifying Issues
Some common AC problems include:
- Insufficient cooling
- Strange noises or odors
- Frequent cycling on and off
- Ice formation on coils
- Water leaks
When to Call a Professional
While some AC issues can be resolved with simple troubleshooting, others require professional attention. Call an HVAC technician if you encounter:
- Complete system failure
- Electrical issues
- Refrigerant leaks
- Persistent problems that don’t respond to basic troubleshooting
Understanding the Efficiency and Capacity of Your AC Unit
The capacity of all but the smallest air conditioners is measured in tons. A one-ton air conditioner has the same cooling capacity as one ton of ice. Sometimes, BTUs are used to describe capacity as well. For cooling purposes, 12,000 BTUs are equal to one ton.
It takes electricity to run the compressor and fans that make an air conditioner work. The fewer watts of electricity used to create a ton of cooling, the more efficient the air conditioner. This is referred to as the Seasonal Energy Efficiency Rating, or SEER. The higher the SEER, the more efficient the unit.
New standards will require minimum SEERs of 14 in northern states and 15 in southern states for air conditioners with outputs smaller than 45,000 BTU/hour. For larger units, the standards will be slightly lower in the South, at 14.5 BTU/hour. If the unit is also a heat pump, that SEER will have to be at least 15 everywhere. The most efficient units available today have SEERs of 26 or higher.
Our Conclusion
Air conditioning systems have come a long way since their invention, offering homeowners a variety of options to suit different needs and preferences. From central air systems to ductless mini-splits and portable units, there’s a solution for every home and budget.
When choosing an AC system, consider factors such as home size, energy efficiency, and long-term costs. Regular maintenance and proper use can significantly extend the life of your system and improve its efficiency.