HVAC System and Components: A Complete Guide

With the seasons in flux and extreme temperatures headed straight for you, it pays to familiarize yourself with your HVAC systems and components. We often go through life relying on our HVACs without ever giving them proper attention. Our HVACs plug along, pumping hot or cold air, and we ignore them. Not anymore.

It’s time to shine a light on the HVAC components and function. The HVAC stands as a marvel of modern air conditioning and heating technology. To provide you with that perfectly treated air, an entire process occurs behind the scenes.

In this basic guide, we’ll walk you through the main parts of an HVAC. After covering each main aspect of an HVAC, we’ll give you some maintenance tips for troubleshooting HVAC systems. By the end, you’ll gain a much better understanding and appreciation of your HVAC.

HVAC Systems Explained

Your air conditioner/heating unit — or HVAC — cools and heats your home. It accomplishes this feat through use of its separate parts all working in harmony. As we discuss the various parts, you’ll see how an HVAC system works. Before we move onto an explanation of the parts, let’s briefly discuss the main types of HVAC systems.

Split Systems

This type of HVAC relies on two main components situated inside and outside your home. It’s literally “split” between both components. Split systems also occasionally go by the name “central air conditioners.” They work by drawing fresh air in from outside and pumping it inside to the furnace or AC unit, which treats the air and disseminates it throughout the house.

The outdoor part houses parts like the condenser and compressor, while the indoor part has the evaporator coils and blower. The condenser pumps a liquid called refrigerant through the coils.


Like regular split systems, mini-splits utilize an indoor and outdoor component. However, unlike their larger relative, mini-splits don’t employ ventilation or ducts. They often sit high up on a wall that provides them with air from outside. They cannot perform the same level of proficiency as a true split, but they sufficiently cool or heat single rooms.


Set the controls to avoid the heart of the sun. The thermostat represents your console, your motherboard, and your best friend. Easily the most visible part of your HVAC, the thermostat sits, mounted on your wall — it’s the device you touch to adjust all your HVAC settings.

In the world of thermostat technology, there are several things to keep in mind. Your thermostat permits adjustments to the function of your HVAC. It operates using a readout display, which shows you several key pieces of information regarding your HVAC including current temperature, the desired temperature you select, fan status, automatic operations, and occasionally other elements such as the date or time.

For our purposes, we’ll quickly run through the main operational features of the thermostat. The two buttons with up and down arrows correspond to higher and lower temperature settings. The number that undergoes raising or lowering, in this case, refers to the optimal temperature, for which you want your system to produce. If you want it colder, set the desired temperature lower than the current room temperature. The same goes for heating — crank up your selected temperature, sit back and wait for HVAC to work its magic.

Depending on how you like your room cooled or heated, you might select the fan setting. Often represented by an appropriate little fan icon, your fan aids in the rapid cooling or heating of your home. As you probably expect, the fan whirls around, pumping the air out faster, while your HVAC compensates by drawing more air inward.

Automatic settings depend on your preferences. Many HVAC users set their systems on a timer. This enables the system to trigger half an hour, for example, before you get home. Come home to a pre-chilled or toasty house. Another feature of the automatic HVAC ability centers on automatic triggering. If your home drops below a certain temperature, the HVAC kicks on and starts bringing the temperature back to the predetermined degree. The mechanism is triggered when the temperature falls out of sync with the preset. For cooling, the evaporator coil-condensing unit is activated. If it’s heating, the heat exchanger kicks online.

It’s often easy to tell if your HVAC presently operates in auto-mode. The word “auto” frequently pops-up on thermostat displays to indicate that automatic cooling or heating is in effect. Auto features let your HVAC operate under the radar of your perceptions, quietly plugging away, ensuring your home stays put at the perfect temperature.

If your thermostat malfunctions, you’ve got a problem. You’ll likely need to replace the unit. There are several possibilities at play: the thermostat readout doesn’t work, it displays the wrong information, or it displays the right information but doesn’t relay it to the system correctly. In any event, it’s necessary to call a professional.


The other main feature of an HVAC system involves the heating capacity of an HVAC system. In many ways, it represents the heart, pumping warmth to all the parts of your home through the ventilation. And like a heart, it pays to ensure it’s working properly. Look after your furnace, and your furnace will look after you.

The furnace takes up a lot of space. Usually located in a basement or tucked away in a front hall closet, the furnace finds a spot and sticks to that location — furnaces are sedentary beasts. If you encounter a furnace in its natural habitat, a secluded area in a house, feel free to approach it. Furnaces are friendly.

In fact, take the opportunity to notice some features of the furnace. You’ll see ventilation tubes coming out of the furnace, which lead to the aluminum ventilation ducts that pump hot air throughout your home.

Essentially, furnaces heat the air before circulating it throughout your house. The HVAC distributes the heated air to its destinations. There are several main types of furnaces. Electric resistance furnaces unsurprisingly run on electricity. They work by blowing intake air over heated electric resistance coils. The air gets pumped onward through vents. The system heats your air in stages to prevent overusing electricity. A malfunctioning electric furnace might use too much power and blow a fuse, but healthy furnaces monitor and curtail their own power use carefully.

Electric furnaces employ highly sensitive sensors to determine whether the electrical capacity has overwhelmed the circuits or not. In a major way, electrical heaters represent an incredibly intelligent option for home HVAC heating and cooling.

Heat pumps offer another common furnace option. Essentially, they transfer hot or cold energy from one area to another. A heat pump either heats or cools the air adjacent to its condenser coils. In this way, it shares many similarities to standard HVAC air conditioner/heaters.

Combustion furnaces burn fuel such as propane or natural gas. They combust an energy source whereby producing heat, which gets pumped throughout your house using ventilation. Unfortunately, these types of furnaces rarely feature combined air conditioning features.

Don’t go poking around in your furnace if it’s not necessary. If you experience any issues, contact an HVAC expert to come and investigate the issue. Don’t try to clean any internal components unless you turn off the HVAC’s power.

Heat Exchanger

The heat exchanger enables the successful convection transfer of energy from a fluid to the surrounding air. It’s what heats or cools the air. The heat exchanger exchanges heat, taking it from the surrounding air and cooling it off. The heat exchanger component includes the condenser coils.

The heat exchanger gets cued when the HVAC powers on. This occurs either through manual triggering or automatic sensing. If the temperature drops below a certain temperature, the heat exchanger kicks to life and starts its process.

Many HVAC systems employ chilled water or a refrigerant as the fluid in the cooling coils. For refrigerant liquid HVAC systems, cold air is produced through a process of vapor-compression. When a refrigerant boils or evaporates, it rapidly draws in the surrounding heat energy. Refrigerants have a much lower boiling point than water. In fact, most air at room temperature possesses enough heat to boil such refrigerant. At higher pressures, the boiling point drops, enabling you to trigger the vapor-compression processes at nearly any household temperature.

Heat exchangers require a little technical knowledge to maintenance correctly. Call a trusted HVAC professional to attend to your heat exchanger. Standard cleaning tools often fall short of meeting the service needs of this piece of machinery.

Evaporator Coil

Evaporator coils concern the cooling aspect of an HVAC. They work by removing heat from the air around them. The refrigerant in the evaporator coil evaporates, creating cold energy that transfers to the nearby air. A blower then expels the air outward and into your house. As with every aspect of an HVAC system, every material is carefully chosen to optimize the heating or cooling process. In this case, the most common metal used in evaporator coils is copper, which acts as an excellent conductor of cold and hot energy. Copper evaporator coils initiate the temperature exchange.

Some systems employ a hybrid heat pump system that produces both hot and cold air. These systems utilize the evaporator coil to initiate heating sequences instead of their traditional cooling function, and they make the most of the evaporator coil, utilizing it for the two main operations of an HVAC.

Occasionally, evaporator coils get dirty. Because they require direct contact with the air in order to transfer their temperature, it’s important not to let gunk prevent their seamless contact. To clean your evaporator coil, first shut off all power to the unit. Then use a screwdriver to open the side panel that stores the coils. Once located, simply wipe them down to the best of your ability.


Vents they play a vital role in the function of an HVAC system. They transport the conditioned or heated air to its destination in your house and act as the final apparatus in the process carried out by the HVAC. Specifically, vents refer to the rectangular, metal-slatted outlets that dispense the treated air. Vents are often installed in the floor, walls or ceiling. The slats that direct the air feature a design that helps direct the air to its desired target. These vents usually employ adjustable slats to enable redirection of the air.

The metal employed in the vents undergoes treatment to enable it to safely deal with prolonged periods of heat or cold exposure. These temperature-treated vents don’t assume the energy of the air. You don’t want to heat your vents. The special metal prevents any heat or cold energy from getting wasted in this final stage.

It’s wise to lubricate the hinges of your vents using a little WD-40, or another product if you prefer. Remove the vents, and bring them outside or to a well-ventilated area. Give them a quick spray, let them dry and return them to their place. This ensures that the vents don’t seize up over time, but remain limber and rust free.


The ducts represent the system of hollow, aluminum, tubes and conduits that course through your house carrying the treated air. The lightweight aluminum material makes for an excellent way to get air where it needs to go. Ducts need strength and durability, and they need to be light weight. Most ducts are made from aluminum, but other materials are used occasionally such as polymers, plastics, fiberglass or polyurethane.

Ducts occasionally begin to leak air as they age. As ducts usually hide in your attic or basement, it’s easy to ignore them. If you suspect your ducts of losing air, enlist a professional. If you have safe access to inspect your ducts yourself, feel for any air coming out. Consider using duct tape for a temporary patch.


For any HVAC user, it’s important to know how to remove and clean your filters. Your filter quality directly determines the cleanliness of your air after it passes through the system. To access your air filters, simply open their access panel, reach in and take them out.

To clean, start by vacuuming out all the debris and dust using the hose extension on your vacuum. Once they’re clean, prepare a solution of equal parts water and vinegar. Let them soak for about half an hour, take them out and let them air dry on a towel. After all that, put them back in, and breathe the reward of your diligence.

Keep Learning About Your HVAC

HVAC units require a little affection from time to time to keep running smoothly. We at StateCE love to discuss HVAC systems and their components. Hopefully we’ve peaked your interest in HVACs and you’re keen to learn more. Continue to research features of your HVAC and keep up your care and vigilance over its condition and status. If you’re curious to learn more, feel free to contact us. We hope to hear from you soon!