Air Conditioning 101

Congratulations! You just bought a new home to call your own. But that also means you now are responsible for maintaining that home. When you’re a homeowner, there’s no landlord or property manager to come by and fix things when they aren’t working right – it’s all on you.

Most homeowners quickly find an ounce of prevention is worth way more than a pound of a cure when it comes to their central air unit.

It’s one of the most complex and crucial systems in your home and you have to play an active role in maintenance if you want it to run as efficiently and as long as possible.

The only way to properly maintain your central air conditioner is to understand the basics of how it works.

This guide is designed to be an introduction for homeowner. We hope you’ll learn:

  • What a central air unit is.

  • The different parts of your central air system.

  • How the different parts work together.

  • How to properly care for the entire system.

Forced Air vs Central Air System

We often get asked about the difference between central air and “forced air” systems. The truth is there isn't much of a distinction between the two terms. Forced air simply means that the system used ductwork and vents. Therefore, a central air conditioning system can also be described as a forced air system.

However, some people do refer to the heating system as the forced air system and the cooling system as central air conditioning.

The Components of Your Central Air Unit

Hundreds of pieces and parts go into a typical central air conditioning system. You don’t need to know every single part, but it’s good to know the core components of a central air unit. They include:

Evaporator Coils

The evaporator unit contains the cooling coils. The evaporator coils are able to remove heat (and humidity) from the air using refrigerant. Dust will buildup and cause your coil to "ice over" if you run the AC without a filter or with the wrong size filter.

Blower

The blower, also called the fan, draws air in over the evaporator coils to be cooled. The blower then pushes the cooled air into and through the ductwork in the home.

Condenser Coils

The heat absorbed by the evaporator coil travels to the "outdoor unit", also known as the outdoor condenser unit, and finally dispelled. The picture shows a condenser unit before and after being cleaned.

Compressor

The compressor is a pump that moves refrigerant from the evaporator to the condenser so that the air can be cooled. There’s also a fan on top of the compressor that helps release the collected heat outside. The compressor is inside the outdoor condenser unit.

Ductwork

This is a system of tunneling that is connected to the air handler and runs throughout the home distributing air through registers that open into rooms. There is a central duct with branch offs into smaller ducts.

Thermostat

This is a device on a wall in the home that is connected to the AC system and allows you to control the air temperature, set schedules or turn the system on and off completely. There are many types of thermostats, some that allow programming, others that allow you to control the comfort of your home from your smart devices.

Air Filter

The air filter is an external component that is usually put into a compartment of the air handler or can be found in an intake vent to capture air particles and contaminants so that they don’t get into the internal components of the air conditioning system. Filters can come in many sizes, make sure you are putting the correct size in your system so it can do its job right.

The Right Central Air Conditioner for Your Home

The first question you’ll want to ask is, what size central air conditioner do I need?

There is no “one size fits all” answer to this question, but it will always have a huge impact on performance, comfort, and cost.

You’ll want the system to be big enough to properly condition the home so that it’s comfortable but going too large can be a waste of money and ultimately ends up being less efficient.

So how do you know what size unit is right for your home?

The rule of thumb is to calculate the number of BTUs that are needed for cooling. You can get a rough estimate using square feet alone, taking into consideration how many square feet are above grade.

For example, a 1,000 square foot house would need at least 18,000 BTUs.

By making sure you have an adequately sized central air unit, you can rest assured that you won’t be spending money in the near future for a replacement.

If you choose a high-efficiency model, you can save 20-50% on your air conditioning costs over time. Plus, there are tax credits and rebates that help to lower the cost of Energy Star central air conditioners.

Cost Factors

The price of the central air unit is going to be a major factor for most homeowners.

Before you start comparing systems, you need to have an idea of your budget. Whether you plan to pay for your system upfront or finance it, this will be a big investment. As you consider the cost of a central air system, you also want to keep maintenance costs in mind.

You’ll need to clean or replace the air filter regularly, so a system that provides easy access to the air handler where the air filter is located is ideal.

It’s also a good idea to plan on having the central air conditioning system professionally serviced once a year. This can help you avoid major repairs that are much, much more expensive.

Routine maintenance may seem like an added or unnecessary expense, but it can actually save you money over time in the form of lower utility payments and not having to pay for expensive repairs.

Reliability and Longevity

Another cost factor is how long you can expect the system to remain in place and whether you’ll have to make costly repairs to keep it running.

It’s always a safer bet to go with an air conditioner manufacturer that has a track record of reliability. There are three things you can do to gauge an air conditioner unit’s reliability and longevity:

  • Read reviews from actual customers

  • Check the manufacturer’s warranty.

  • Look into the performance of past products

Here’s an example of how air conditioners can compare:

A Trane air conditioning system may cost more upfront, but they are known to be very efficient and reliable. Or you could select an Amana system that costs less to install, but the warranties only offer coverage for 5-10 years as opposed to up to 20 years for Trane units.

Ultimately, a lot goes into selecting the best central air conditioner for your home.