You’ve probably heard the term ‘HVAC’, whether it be in the context of a home improvement conversation or maybe you’ve heard a local HVAC company’s advertising.

So what is an HVAC system?

HVAC refers to the systems used to heat and cool homes and other buildings. In addition to producing a comfortable temperature, HVAC systems also ventilate your home and ensure fresh air by exchanging air from outside.

HVAC stands for heating, ventilation, and air conditioning. An HVAC system encompasses all the components of the system, from a furnace, heat pump, air conditioning unit to the ductwork through which the heated or cooled air flows.

What Is HVAC & What Does An HVAC System Do?

An HVAC system heats, cools, and regulates temperatures in residential and commercial buildings. HVAC systems move air from outdoors to indoors and vice versa. Air coming into the system is heated or cooled according to the desired temperature. HVAC systems equipped with a filter filter the air coming into the space for contaminants. They bring in fresh air so you can breathe easier and be healthier.

Filtered HVAC systems improve indoor air quality by removing dust, moisture, smoke, smells, airborne bacteria, carbon dioxide, and other gases, as well as maintaining temperature and resupplying oxygen.

You can find HVAC systems in anything from apartments, to condos, to single-family homes.

How Does An HVAC System Work?

The important thing that an HVAC system does is move air. It takes hot air from a furnace or heat pump and moves it into the home or building. In hot months, a heat pump removes hot air.

In the case of air conditioning, the air conditioning unit moves cold air into the home.

The furnace, heat pump, and air conditioner in a house extract or generate heat, which is then moved around the house with the aid of the blower and ductwork.

Here’s how each component of an HVAC system works:

How Central Air Conditioning System Works

Contrary to popular belief, air conditioners and heat pumps do not produce cold air; rather, they transport heat from inside a house to the exterior unit, where it is vented outdoors.

A cooling system’s refrigerant plays an important role in this. The refrigerant can either be a gas or a liquid, depending on the pressure. Depending on its location, the HVAC system modifies the refrigerant’s pressures. Once it reaches a different pressure, it can collect ambient heat and expel it.

Heat is gradually removed from the house by repeatedly traveling from inside to outside while regulating the refrigerant’s pressure in accordance with that process.

A heat pump has the ability to take heat from the outside and transfer it inside. A heat pump can still take in heat from the outside when it’s extremely cold, but it will do so less effectively. This is why an electric furnace, which has compatible technology and enhances the heating capabilities of the heat pump, is typically used in conjunction with a heat pump.

Types Of Heaters & How Heating Works

Most homes will have a furnace (heater) heating their home. There are several types of furnaces, each one suited to specific needs. A natural gas furnace uses natural gas to heat your home, while electric furnaces use electricity to heat your home. Both types of furnaces require regular maintenance. Some homeowners prefer propane furnaces because they run very quietly and don’t produce much smoke. However, some people find oil furnaces too noisy.

Furnaces come in different sizes and can use different fuel sources to heat your home. They range from small units used in apartments to large ones used in single-family homes.

Natural Gas Furnace Types

There are four main types of natural gas furnaces: forced air, radiant, packaged, and ductless. Each type serves a different purpose. Forced air furnaces provide the most consistent temperature throughout the house. Radiant furnaces distribute warm air evenly across the floor, providing comfort without wasting energy. Ducted systems make it easier to route hot air where you want it. Packaged units combine the best features of both radiant and forced air systems.

Electric Furnace Types

Electric furnaces are usually smaller units designed to work with existing electrical wiring. These units are often installed in attics or basements. They’re great for those living in older houses and/or buildings that lack adequate ventilation. Many of these units are also quiet and efficient.

HVAC Ventilation

The term “ventilation” refers to any of the attached systems within a home that helps to process and move air around the home. These include ductwork, floor, walls, and ceiling vents, as well as chimney flues, PVC vents, and other ventilation holes. All of these holes allow warm or cold air to flow out of the home. They also serve to keep smoke and odor away from the home, and prevent moisture from entering the home.

Inadequate ductwork can slow down a heating or cooling system because it prevents air from moving efficiently throughout the home. If you’re having trouble keeping your home comfortable during the summer months, check to see if your ductwork needs repair or replacement.

HVAC System Components

There are many different pieces of equipment that go into an HVAC system, including fans, blowers, heat exchangers, compressors, expansion valves, dampers, ductwork, vents, filters, and much more. Here are some of the most important parts that make up an HVAC system:

Air Return
An air intake is the part of your HVAC system that brings fresh air into your home. Your air intake is usually located near the top of your ductwork, and you’ll need to install an air filter at this location to keep out particles and other contaminants. You should also clean the filter regularly to ensure proper airflow.

Warm air is drawn into the main part of the unit by the blower. Keep in mind that your HVAC system will be more robust and more durable the more effectively this air goes through it.

Coils chill the air as it goes through with a little assistance from the refrigerant and are typically another component of the outside unit. Getting a yearly coil inspection along with the rest of your HVAC system is a good idea. If your coils start to ice over, you should get an inspection of the filter and/or refrigerant levels.

A compressor converts refrigerant from a gas to a liquid, which allows for dumping heat out of the HVAC system. Compressors are an essential component of air conditioning systems. A properly functioning compressor will keep your HVAC system running smoothly. When you start noticing problems with your system, check your compressor first. It may be the root cause of many system issues.

Air ducts are the passageways through which heated or cooled air flows through to adjust the temperature of your home. Every two to five years, your ducts should be professionally inspected and cleaned in order to maintain proper operation.

Electrical Components
There are several electrical parts that are essential for an HVAC system to operate. Some of the electrical parts include wiring, batteries, fuses, breakers, and more. If any of these components fail, it can cause an HVAC system to underperform or break down, which is why it’s a good idea to get yearly inspections because these issues can be caught before it results in system failure.

Exhaust Outlet
Your heating system also needs an outlet to expel heat. A chimney flue or ventilation stack is usually located at the top of your house. You should check it once a year and clean out any debris. If there are cracks or holes in the roof, you may need to replace them.

A filter is an important component of any HVAC system. Your filter helps remove impurities from the air before it enters the rest of the system. A dirty filter will cause problems like poor airflow, increased energy usage, and reduced comfort levels. Regularly changing your filter will help you avoid these issues.

Humidity Control
The majority of contemporary HVAC systems can control humidity. The evaporator coil in your HVAC system condenses water vapor from the air. This happens when the chilly evaporator coil comes into contact with the warm, humid air in your home. Your home becomes less humid as a result of the liquid getting condensed out of the air. The moisture that the evaporator coil has gathered is transported to a drain and subsequently sent outside.

Outdoor Unit
When someone mentions HVAC, this is probably the component that comes to mind for most people.

The fan that moves air through the ducts in your home is housed in the outdoor unit.

Keeping vegetation and debris away from your HVAC’s outdoor unit is important because it can cause major issues if anything gets sucked in.


Modern electronic thermostats use sensors to determine if your house is too hot or cold. Thermostats can be programmed to change temperatures based on time of day, weather conditions, and other factors. They also offer many additional features such as internet connectivity, remote access, and more.

If you have an older thermostat, it’s worth considering an upgrade due to how convenient they are.

Types Of HVAC Systems

There are four main types of HVAC systems, each with its own purposes and pros and cons.

Duct-Free Split System

As the name implies, a duct-free, or mini-split, is an HVAC system that does not use air ducts. It has high initial costs but significant advantages for particular applications.

These HVAC systems offer more independent control because they’re separate units in each room. These devices are often connected to an outdoor compressor and installed on walls.

It can be costly to install these units on an existing property because they require fitting them to a window or cutting a hole in a wall. These units are ideal for new additions to residences, such as garages, or expansions because they can be easier to install rather than having to fit your existing duct system to the new space.

These types of HVAC units are also a convenient option for service businesses such as hotels or venues, allowing individuals to control their own temperature. Another advantage is energy conservation, as only the rooms that are actually being used get heated or cooled, preventing energy waste in unoccupied rooms.

People who are retiring or downsizing may want to install these systems to keep the rooms they use comfortable and prevent the energy use of the areas they don’t use. Like any HVAC system, they require regular cleaning and maintenance.

Heating And Air Conditioning Split Systems

Heating and cooling split systems are the most popular kinds of HVAC systems. The system is divided into two primary parts, one for cooling and one for heating. These systems stand out because they have readily identifiable indoor and outdoor units. These HVAC units have an exterior cooling system that circulates refrigerant through compressors, coils, and fans to cool the air and expel hot air. These are often the sizable AC units that are installed outside of homes and operate in the summer.

Heating and cooling split systems also include a heater that uses gas to heat the house. This heater is typically found in a basement or other storage area. Either a fan or an evaporator distributes this to move the air about. Most homes can be maintained at the desired temperature using this technology, which employs a conventional thermostat to control the temperature. Most units come equipped with humidifiers and purifiers as well, ensuring that your home or office is comfortable no matter the weather. These systems are the most commonly utilized since they may be used by everyone, regardless of needs or environmental conditions.

Hybrid Split System

Hybrid HVAC systems are like split systems, but there are some key differences between the two. These systems are becoming more popular because they can save money on energy costs.

This is because they use an electric hybrid heating system, which is different from other HVAC systems. This is an important difference because it allows homeowners to choose how to heat and cool their home, as they can switch between gas power, which is faster and more complete, and electric power, which is more efficient and quieter.

This system uses traditional ducts and thermostats.

Packaged Heating & Air Conditioning Systems

The most specialized sort of HVAC equipment is packaged heating and air. The system is a house-stored, self-contained heating and cooling equipment. It is typically kept in a storage area on the top floor or in the attic and is used to heat and cool homes. It can be placed within the house if an outside is not an option due to its tiny size, which makes it helpful for smaller spaces or dwellings. These HVAC systems can also be incredibly effective and simple to maintain. Since the heating system is not as strong as other options, they are typically employed in warmer climates. Although various types can mix gas and electric capabilities, the heat is often created electrically.

Common HVAC Ratings And Certifications

When you need a new energy-efficient HVAC system, there are many different ways to measure its effectiveness. Energy Star is an international program that rates products according to their energy consumption. ENERGY STAR® qualified equipment meets strict requirements for energy efficiency, while also meeting other important criteria like noise levels and indoor air quality. There are also local programs, like those run by the U.S. Department of Energy, that rate the efficiency of specific types of equipment.

This rating refers to the Annual Fuel Utilization Efficiency, which is a way to measure how well a gas furnace turns fuel into energy.

The Air Conditioning, Heating, and Refrigeration Institute is an independent lab that gives SEER ratings for HVAC equipment that are accurate and fair. They are in charge of making sure that a manufacturer’s claims about efficiency are true.

This stands for Energy Efficiency Ratio, which is a way to measure how well your air conditioner works when the temperature outside reaches a certain level. The more stars a system has, the better it works.

This refers to Heat Seasonal Performance Factor. It’s a way to measure how well heat pumps heat a room. The more efficient a heat pump is, the higher the HSPF number.

MERV Rating
This means Minimum Efficiency Reporting Value, which is a standard for judging how well an air filter works overall. The filtration system is better if it has a higher MERV rating. Better filtration is important because it keeps your family from breathing in harmful substances.

NATE Certification
When you want to hire an HVAC tech, the NATE certification is important. IT stands for North American Technician Excellence, which is a certification program for HVAC professionals that is run by a non-profit group. By making sure your contractor has this certification, you can be sure that they are qualified and skilled for the job.

Seasonal Energy Efficiency Ratio is a way to measure how well an air conditioner or heat pump works. The more stars a system has, the better it works. The minimum SEER rating set by the government is 13 or 14, but it can go as high as 25.

Frequently Asked Questions
What’s The Difference Between HVAC And Air Conditioning?
The “AC” in HVAC refers to the air conditioning part of the system. But you should think of them as interchangeable terms, as HVAC encompasses the entire system that regulates your home’s temperature and provides fresh air, including the air conditioner.

How Long Does An HVAC System Last?
You may be curious about the lifespan of a new HVAC system now that you know what they are and how they work. The lifespan of an HVAC system really depends on the equipment and other factors such as how you use it. However, if you perform the necessary yearly maintenance, your HVAC system should stay working for a very long time.

What Is An HVAC Tune Up?
An HVAC tune up involves having an HVAC technician inspect your system for performance and any potential points of failure. It’s optimal to set up an appointment for your air conditioning each spring and schedule an inspection and cleaning for your furnace each autumn. This allows you to get your HVAC system prepared for the upcoming cooling or heating season and get it operating at its best.

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