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How Does A HVAC System Work?

Your HVAC system is the core of heating and cooling within your home. If you get a high-quality system, you’re never going to feel uncomfortable at the height of summer or in the dead of winter. So how does one of these systems work?Looking for Commercial HVAC? Look no further, Commercial HVAC Services  has you covered.

HVAC systems are, effectively, everything from your air conditioner at home to the large systems used in industrial complexes and apartment blocks. A sound HVAC system aims to provide thermal control and indoor comfort, and one that is designed using the principles of thermodynamics, fluid mechanics, and heat transfer.

The three primary functions of an HVAC system are interrelated, especially when providing acceptable indoor air quality and thermal comfort. Your heating and air conditioning system are often one of the most complicated and extensive systems in your home, but when it stops working, you’ll know soon enough! There are nine parts to your HVAC system that you should be familiar with: the air return, filter, exhaust outlets, ducts, electrical elements, outdoor unit, compressor, coils and blower.

The oversized air conditioner boxes that you might see on top of apartment blocks or offices are examples of (the visible part of) HVAC systems. They’re typically deployed in large industrial buildings, skyscrapers, apartment blocks, and extensive interior environments. They’re also an essential component of environments where health regulations are requiring that Temperature and humidity be kept at certain levels, using air taken from outside

But heating and cooling systems you use in your home are also HVAC systems. They may take a different form, but many of the fundamental principles determining how they operate, as well as their efficiency, cross over from the smallest of personal devices right through to the most significant commercial installations.

Heating and Cooling Distribution Systems

It’s essential to understand how different heating and cooling distribution systems work. This will help you to understand your HVAC system better.

Heating systems can take a couple of different forms. Some are furnaces that burn material to provide heated air through the ductwork. At the same time, another popular choice is boilers that heat water for steam radiators, or forced-water systems with baseboard radiators, electric heat, and heat pumps. A furnace will generally operate on natural gas or propane, while a boiler will use gas or oil to heat the water.

Another option is a radiant floor, also known as a hydronic heating system. These use piping under a foundation and are made up of flexible tubes that are filled with water or a glycol solution. These can heat any floor, including concrete, and are an efficient method of providing warmth in a home. They can even be retrofitted into wooden flooring, though they need to be carefully installed in sheathing for wooden floors.

Cooling systems Air conditioners come in many forms, from the massive boxes designed to cool an entire house to a portable window-mounted box that can be pulled out and used in colder climates to handle short summers. Many air conditioners can even be installed by the owner, with ductless mini-split systems a popular choice. Installation is still a significant project, as the interior and exterior elements of the system need to be correctly connected, but they are relatively inexpensive to buy and run.

For dryer climates, evaporative coolers are a popular choice. They draw outside air into the system, passing it through water-saturated pads, which calm and moisten the air before pushing it into the living space and displacing the hot air.

Forced Air Systems

The forced air system takes hot or cold air and forces it through metal ducts using a blower. Hot air is forced through one set of vents, and cold air is sent through another set of ducts, depending on whether you’re using the air conditioner or the furnace.

The most common problem with forced air systems is blowouts. Towards the end of their lifespan, the blowers can malfunction and stop working. It’s also not uncommon for cheaper plans to have issues with volume.

Gravity Systems

 Gravity systems operate using the principle that cold air sinks, while hot air rises. Therefore, a gravity system cannot be used in conjunction with an air conditioning system. These systems are positioned in the basement. When switched on, the warm air rises through the ceiling and heats your home. When it cools, it sinks down again and is reheated.

Radiant Systems

Radiant systems also come with the same problem as gravity systems. They cannot be used in conjunction with air conditioning systems. A radiant heating system heats the floors, walls, or ceilings of a room. Most commonly, though, they’re used to heat implements like radiators, which distribute heat around your room. The main downside of radiant systems is the pipes used to transport hot water are prone to malfunction, either due to mineral deposits or general wear and tear.

List of HVAC System Parts and How They Work

It’s essential to understand the various parts that make up the HVAC system, so you know how they work together. Despite different models having unique features, the differences between their core components are comparatively few. There are four main parts to every HVAC system.

The furnace utilizes natural gas or oil to heat the air. Within the furnace is a heat exchanger, which is the part of the stove responsible for heating up the air to the Right Temperature. You’ll typically find the stove in the attic, basement, or a specially designed closet space.

The air conditioner cools the air and is found outside of the house. It uses electricity and coolant liquid to reduce the Temperature of the air while sending hot air outside and cold air inside.

Ductwork is the transit system for hot and cold air throughout the home. It moves it throughout the interior of your home.


This is the most prominent portion of your HVAC system, and the piece you’ll interact with most. Usually installed on an easily accessed wall, it can be set manually and programmed to keep your home at your ideal temperature. When the ambient temperature gets too hot or cold, the thermostat triggers your HVAC system to start circulating air as needed.

The thermostat acts as the brain of your system. It can turn your system on and off, control the Temperature and also operate any other unique features that you have installed alongside your course.

A thermostat is an electrical device inside the home that senses ambient air temperature and then regulates HVAC functions to keep the house at a set temperature. It’s a closed-loop device that works to close the gap between desired Temperature and actual Temperature.


Your furnace is the star of your HVAC system, and it can be huge—it’ll require the most space out of all of the different components. The furnace is designed to heat air, which is then distributed to other portions of your home via ductwork or piping. Furnaces use varied heat sources, including solar energy, heat pumps, electric resistance, and combustion.

Evaporator coil

The evaporator coil is used to cool down the air when your thermostat is set to a lower temperature. This cold air is then funnelled throughout your home. When we’re thinking about an HVAC system as a cycle of condensation and evaporation, the evaporator coil would be the counterpart of the condenser. It’s the first stop in this closed-loop system after the compressor, holding chilled liquid refrigerant from that component. The evaporator coil is located inside the blower compartment or air handler, where air moving past the unit speeds up evaporation.

Condensing unit

This unit is found on the outside of your home and filled with what is called refrigerant gas. When the refrigerant is cooled, the condensing company pumps this liquid to the evaporator coil to be transformed into a gas again.

To understand condensers, you must first understand the process of cooling. It starts with a gaseous refrigerant that is compressed until it becomes a liquid, which is then evaporated and allowed to condense so it can turn into a liquid again. You can think of it as a cycle of compression and expansion, or evaporation and condensation, as a result, is the same.


These are the outlets that help distribute heated and cooled air from the duct system into the various rooms of your home. They’re generally found near the ceiling with angle slats, designed to send the air downward. It’s essential to ensure these vents don’t become blocked.

The air that’s coming from the HVAC unit or furnace has to be distributed to the home somehow, and that’s where the vents come in. The blower forces air through a network of ducts, and the vents (or registers) are outlets for the ducts that allow air to circulate into the rooms.

Refrigerant lines

These lines carry refrigerant to the condensing unit in the form of gas. This gas is transformed into liquid form, then transferred back to the evaporator coil.

Refrigerant lines are the tubing that carries the refrigerant through the system, from the compressor to the evaporator and condenser, then back to the compressor again. This process is controlled by valves located along the refrigerant lines.

Controls for Heating and Cooling Systems

The heart of your heating system is the thermostat. This is heat-sensitive and controls the temperature of your home. It also can respond to the current air temperature by itself.

The setpoint is the Temperature you set manually as your preferred Temperature. If the thermostat notices it is above or below the setpoint, it will act accordingly, by turning the furnace on or off. The critical component is the bimetallic element that contracts or expands when the temperature changes within your home.Check out our range of domestic air conditioning to help in your problem.

If you have an older thermostat, it will have two exposed contacts. When the room cools, the bimetallic element bends. It contacts electronically, before making a second contact. The system activates when the second contact turns, which launches the heating system.

There are four types of HVAC systems: split systems, packaged units, heat pumps, and ductless mini-split systems. Traditional split systems are indoor and outdoor units that are attached to an extensive ductwork system that runs through the house to air vents in each room. Packaged systems and heat pumps are contained in one unit and ductless systems, as the name suggests, don’t require ducts. The thermostat controls all central air systems.

Understanding the different varieties of HVAC systems can save you a lot of time while you’re considering your options, and help you better understand how HVAC works. Narrow down your choices before you begin shopping, and get a clear picture of what you need to make yours function at its best.

Air Return

Your air return is the part of your system that marks the starting point of the ventilation cycle. This return sucks in air, draws it through a filter, and then passes it into the central system. Pro tip: Make sure to dust your returns frequently as debris and dust can quickly build up on your filters.


Your filter is the second part of the air return in which the air is drawn through. Pro tip: Make sure to change your filters regularly to keep your system in tip-top shape.

Exhaust Outlets

Another part of your system is the exhaust outlets where the exhaust created by the heating system is expelled. Pro tip: Check your chimney flue or vent stack annually and tune it up if necessary.


Your ducts are the channels in which the heated or cooled air passes through. Pro tip: Get your ducts cleaned every 2 to 5 years in order to keep everything in working condition.

Electrical Elements

This part of your system can be a bit trickier, but often problems originate here first. Pro tip: If something isn’t working right check for a tripped breaker or dead batteries in your thermostat.

Outdoor Unit

This is likely the part of your system you think of when someone mentions an HVAC system. The outdoor unit houses the fan, which provides airflow. Pro tip: Keep your company clear of debris and vegetation as it can cause severe problems if plants are sucked into your lover.


As a part of the outdoor unit, the compressor is responsible for converting refrigerant from a gas to liquid and sends it to the coils. Pro tip: If something isn’t working quite right, check your compressor. It is often the cause of many system failures.


Usually another part of the outdoor unit, coils cool the air as it passes through with a little help from the refrigerant.

 Pro tip: Check your locks annually. If they freeze up, you may want to check your filter and refrigerant levels.


The blower draws in warm air through the main section of the unit. Pro tip: The more efficiently this air moves through, the more durable your system will be.

Types of HVAC Systems

Understanding the different varieties of HVAC systems can save you a lot of time while you’re considering your options, and help you better understand how HVAC works. Narrow down your choices before you begin shopping, and get a clear picture of what you need to make yours function at its best. We have the best air-conditioning maintenance in Outline Air at Melbourne,Australia

Heating and air conditioning split system.

This is the traditional type of HVAC system. It has components both in and outside of the home. Generally, it contains an air conditioner designed to cool refrigerants outside of your house, and a furnace with a fan or coil inside the house. These systems feature ductwork, which carries air throughout the various rooms of your home. Newer, energy-efficient split systems offer unique accessories, including air purifiers, cleaners, and humidifiers.

Duct-free split system

 This system, as its name implies, is designed to function without ductwork. Also known as a ductless mini-split, this can be a good option for retrofitting homes with non-ducted heating systems. They’re also a good option for rooms that can’t be outfitted with the distribution.

Zoned systems

This type of HVAC system lets you cool or heat different areas of your home by controlling valves or dampers within the ductwork. These dampers are used to block airflow selectively. Zoned air systems can save you a great deal of money, as they allow you to control which areas are heated or cooled at specific times.

Humidity control

Most modern systems offer optional humidity control features. Humidifiers and dehumidifiers can be added depending on your climate needs. These systems let you automatically control the humidity levels throughout your home when your HVAC system is running. In some parts of the country, humidity can be as much of a problem as high temperatures. Ever heard this weather forecast? “Temperature is 90 degrees, feels like 100 degrees.

Choose the right-sized system:

Bigger isn’t always better, and this is especially true of HVAC systems. Don’t purchase a larger unit than your home needs. If the system is too big for the amount of square footage it’s cooling, it will cycle through its rounds too quickly. This could lead to excess condensation, mould, rot, and of course, decreased comfort. Ask your contractor for help determining the appropriate sizing.

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