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Mastering Comfort: The Ultimate Guide to Central Air Conditioning System

What makes the central air conditioning system important? What are its components? How does it work? Our HVAC content team set out to give a brief highlight of the system. Let’s dive right in.

Anyone in the construction industry will tell you that no one wants to invest in a home that isn’t comfortable to live in because that means the home will be hard to resell too. A leading building materials provider in Nairobi agrees that in ensuring safe and healthy spaces, many components come into play, chief among them being air conditioning.

The air conditioner is among the most prominent players in enhancing your space aesthetically and functionally. While there are several air conditioners to choose from, what makes the central air conditioning system stand out?

Well, for starters, a central AC is not only easy but also convenient to operate. What’s more, it offers better efficiency than typical room air conditioners.

So, the accompanying benefits are endless, whether switching from a window air conditioning unit to a central air conditioning system or installing a new central AC for the first time.

That said, while it may seem costly, the payoffs of installing a central AC system will ultimately prove worthwhile. From better air quality, reduced humidity, and reduced allergens to better indoor living, you will be glad you installed a central air conditioning system!

This piece provides more information about a central AC system, its types, components, and how it works. By the end of the article, you will be a more educated buyer should you consider installing a central AC in your home or commercial space.

Read ahead.

What is a central air conditioning system?

Thanks to its quick and efficient cooling, quiet operation, and enhanced aesthetics, the central air conditioning system has grown in popularity.

So, how do you describe or identify a central AC system?

A central air conditioning system is a cooling system that works by cooling air at a centralized location before distributing the cool air to several different rooms or spaces through fans and ducts.

In other words, once the air is cooled sufficiently, the central AC system circulates it to the relevant rooms with the help of both supply ducts and return ducts.

The supply ducts and registers are typically installed as openings on floors, ceilings, or walls with grill covers. They are responsible for transporting cool air from the central cooling unit to your home or commercial space.

As the cooled air circulates throughout your space, it picks up the heat within the room and gets warmer. The warm air is then returned to the central AC system for cooling through another set of return ducts and registers.

Through this simple cycle, your central cooling unit cools while dehumidifying your air for a comfortable, healthy, and livable space.

Thus, a central air conditioning system differs from a window air conditioner. While the central AC features many parts and relies on a building’s duct system, the window AC comes as a standalone unit with no extra parts.

That means the central AC is ideal for cooling larger rooms, while the window AC performs well when used to cool single rooms or smaller spaces.

What are the types of central air conditioning systems?

Having understood what a central air conditioning system is, let’s review the types available.

Usually, central air conditioning systems come as either:

  1. Split-system air conditioners
  2. Packaged air conditioners

If you want to install central heating in your space, which of the two options is right for you? Take a closer look at the unique distinctions.

Split-system air conditioners

As the name states, split-system AC units come with split components. They feature a separate evaporator coil split from the compressor and condenser coils.

The evaporator is often located inside an indoor cabinet somewhere. On the contrary, the compressor and condenser are housed in an outdoor cabinet. That means the AC comprises an indoor and outdoor unit linked with copper tubing.

With that in mind, split-system AC units are the most common type of central AC systems thanks to their flexibility and value-addition. They are also the most economical to install if your space has a furnace but lacks an air conditioner.

Furthermore, split-system AC systems are ideal for homes or commercial properties with additional space to accommodate large indoor cabinets.

Packaged air conditioners

From the sound of the name, packaged air conditioners house all their significant components (evaporator, compressor, and condenser) in a single metallic cabinet to save installation space. Typically, the housing cabinet sits on a designated concrete slab next to the structure’s foundation or on the roof.

The packaged unit (sitting outdoors) links to the building through supply and return ducts emerging from the exterior walls or roof. Therefore, it draws air from inside the building, cools it sufficiently, and then sends it back through the special ductwork.

You don’t need a separate indoor furnace with a packaged AC unit. Most such systems come equipped with electric heating coils to provide central heating.

Packaged air conditioners are suited for buildings with little to zero crawlspaces or lack a basement.

What are the components of a central air conditioning system?

Beyond the essential operation of your central air conditioner, it is imperative to master the components of your cooling system. This knowledge comes in handy when diagnosing and possibly troubleshooting problems with the unit.

Here is a closer look at the main parts of your central AC system and how they fit together to keep your indoor temperature comfortable.


Sitting at the heart of your central AC system, the compressor plays an integral role in keeping your space cool and comfy. The compressor sits next to the condenser in the outdoor cabinet of your cooling system.

It works by compressing (adding pressure to) the refrigerant vapor. This effect increases the vapor’s pressure while converting it into a hot gas. The extra pressure (force) then pushes the denser refrigerant into the condenser coil for cooling.

Thus, a compressor’s primary role is to complement a condenser’s cooling function by pressurizing the refrigerant.


As the refrigerant absorbs warm air from your space, it passes through the compressor for pressurizing into hot vapor. Once the hot refrigerant vapor lands on the condenser from the compressor, it is relieved of all its heat.

As the vapor reaches the condenser, it is also converted into a liquid as it cools. From there, the liquid refrigerant flows through the condenser and condenser coils before being circulated indoors for another cooling cycle.


Safely tucked inside your central air conditioner, the evaporator serves the direct opposite function of the condenser. After cooling in the condenser, the cool liquid refrigerant flows to the evaporator.

The refrigerant encounters a lower pressure in the evaporator and turns back into a gas. As a lighter gas, it absorbs the warm air around it to cool your indoors.

After absorbing the hot indoor air, the warm refrigerant flows to the compressor and the condenser. This cooling cycle continues until your indoor space reaches a comfortable temperature.

Expansion valve

Think of the expansion valve as an intermediary equal to but opposite in function to the compressor. That is to say, while the compressor helps the condenser by increasing the refrigerant’s pressure, the expansion valve assists the evaporator by reducing it.

Thus, the expansion valve helps to effectively reduce the pressure of the liquid refrigerant to facilitate conversion back into a gas when passing through the evaporator.

How does central air conditioning work?

As detailed above, the central air conditioner works through the collaborative function of its different components.

The whole operation revolves around the system’s refrigerant and how its changing states (temperature and pressure) support the cooling process of your ambient air.

The cooling process of a central AC system starts with the thermostat. Usually located centrally inside the building, the thermostat monitors the indoor temperature. When it detects that the indoor air temperature needs some regulation, the thermostat alerts your central cooling system’s indoor and outdoor components.

When the different components start running, the indoor fan drives out indoor hot air through return ducts. The hot air is then filtered before passing over the evaporator coil. In this very instance, the evaporator is busy converting the liquid refrigerant from the condenser into a gas.

The gaseous refrigerant then absorbs all the heat from the hot indoor air before heading outdoors to the compressor and condenser through copper tubing for cooling. Once cooled, the indoor unit’s fan blows the cooled air back into the building through the ductwork.

The cold air then begins absorbing indoor hot air again. The cycle repeats itself until the desired indoor temperature is reached.

technical specs of a central air conditioning system

FAQs About Central Air Conditioning Systems

1. What is a central air conditioning system? A central air conditioning system is a type of cooling system that uses a centralized unit to cool and distribute air throughout an entire building or home. It typically consists of an outdoor unit, an indoor unit, ductwork, and a thermostat.

2. How does a central air conditioning system work? The central AC system works by extracting warm air from inside your home, cooling it through a refrigeration process in the outdoor unit, and then circulating the cooled air back into the indoor spaces through ductwork and vents.

3. What are the advantages of using central air conditioning? Central air conditioning offers consistent and even cooling throughout the entire space, provides better indoor air quality when paired with proper filtration, and doesn’t require bulky window units that obstruct views and create noise.

4. How energy-efficient are central AC systems? Newer central air conditioning systems often come with high energy efficiency ratings (SEER – Seasonal Energy Efficiency Ratio), which can result in lower energy bills. Regular maintenance, proper insulation, and thermostat settings also contribute to energy efficiency.

5. Can I install a central AC system myself? Installing a central air conditioning system is a complex task that requires expertise in HVAC (Heating, Ventilation, and Air Conditioning). It’s recommended to hire a licensed professional for proper installation to ensure safety, efficiency, and warranty coverage.

6. How often should I replace the air filters? Air filters should be checked every 1 to 3 months and replaced as needed. This helps maintain good indoor air quality and ensures that the central AC system operates efficiently.

7. What maintenance does a central AC system require? Regular maintenance includes cleaning or replacing air filters, cleaning the evaporator and condenser coils, checking refrigerant levels, lubricating moving parts, and ensuring proper airflow. It’s advisable to schedule professional maintenance annually.

8. Why is proper sizing important for a central AC system? Choosing the right size for your central AC system is crucial for optimal performance. An oversized unit can lead to short cycling (frequent on/off cycles), inefficiency, and uneven cooling, while an undersized unit won’t effectively cool your space.

9. Can a central AC system be zoned? Yes, central AC systems can be zoned by using dampers in the ductwork to control the airflow to different areas or rooms. This allows for personalized temperature control and energy savings by only cooling the zones that need it.

10. How can I improve the efficiency of my central AC system? To improve efficiency, you can upgrade to a higher SEER-rated unit, enhance insulation and weatherproofing in your home, use a programmable thermostat, seal ductwork for better airflow, and ensure proper maintenance and regular filter changes.

11. What’s the difference between central air conditioning and ductless mini-split systems? Central air conditioning systems use ductwork to distribute cooled air throughout a building, while ductless mini-split systems provide targeted cooling to specific zones without the need for ducts. Ductless systems are more flexible in terms of installation and can be ideal for homes without existing ductwork.

12. How do I know if my central AC system needs repairs? Signs of potential issues include reduced cooling efficiency, unusual noises, inconsistent temperatures, unusual odors, and increased energy bills. If you notice any of these symptoms, it’s best to schedule a professional inspection and repairs if necessary.

13. What’s the typical lifespan of a central air conditioning system? The average lifespan of a well-maintained central AC system is around 10 to 15 years. However, factors such as usage, maintenance, and quality of installation can impact how long the system will last.

14. Can a central AC system also provide heating? Some central AC systems can be part of a HVAC setup that provides both cooling and heating through a heat pump. This is called a “heat pump system,” and it uses the same ductwork and components to provide heating during colder months.

15. Are there eco-friendly options for central AC systems? Yes, there are energy-efficient and environmentally friendly options available. Look for systems with high SEER ratings, energy-efficient compressors, and those that use more environmentally friendly refrigerants, such as R-410A.

16. How does a central AC system affect indoor air quality? Central AC systems can help improve indoor air quality by filtering out dust, allergens, and pollutants through the air filter. Upgrading to higher-quality air filters or using air purifiers in conjunction with the system can further enhance indoor air quality.

17. What’s the difference between the compressor and the condenser unit? The compressor is the “heart” of the central AC system and is usually located in the outdoor unit. It pressurizes and circulates the refrigerant, while the condenser unit in the same outdoor component releases the heat absorbed from inside the building.

18. Can I install a central AC system in an older home without existing ductwork? Yes, it’s possible to install a central AC system in an older home without ductwork. However, this might involve retrofitting ducts into the existing structure, which can be complex and costly. Ductless mini-split systems are often a more straightforward option for such situations.

19. What should I consider when choosing a central AC system for my home? Factors to consider include the size of your space, energy efficiency ratings (SEER), budget, local climate, insulation, and the reputation of the manufacturer and installer. Consulting with an HVAC professional can help you make an informed decision.

20. Can I control my central AC system remotely? Yes, many modern central AC systems come with smart thermostats that allow remote control through smartphone apps or voice assistants. This feature enables you to adjust temperature settings and schedules even when you’re away from home.

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