HVAC is an acronym that stands for heating, ventilation, and air conditioning. The systems that comprise HVAC take in indoor air and cool or heat it before blowing it into space, according to the American Society of Heating, Refrigerating, and Air-Conditioning Engineers.

According to PlumbSmart Plumbing Heating and Air, an HVAC system consists of a furnace, air conditioner, and ductwork that connect to a thermostat. The thermostat regulates the system based on home comfort preferences and climate needs.

Heating

In its basic form, an HVAC system consists of three major components: a heating unit, a cooling unit, and ducts to move the air. Depending on your unique needs, a professional will generally install a combination of these systems in your home or business.

The first thing an HVAC system does is bring fresh air into a building. While old-fashioned architecture made this easy, as builders created more tightly sealed buildings, it became necessary to create mechanical ventilation systems to take air in from the outside and push stale indoor air out.

This ventilation system takes in air from windows, doors, and cracks, as well as venting stale indoor air outdoors. It then uses fans and blowers to move that fresh air throughout the building, circulating it for better air quality and regulating temperature.

Once that fresh, conditioned air is in place, it’s time to heat or cool the interior of your home or office. This can be done with a furnace or, in warmer climates, a heat pump.

Furnaces work by burning fuels like natural gas or propane to produce heat, which is then blown into the house through ducts. Alternatively, a heat pump can heat and cool a house using a series of pipes filled with liquid refrigerant. The refrigerant can be redirected to absorb heat from the air or to release it into the house, as needed.

These systems are regulated by thermostats that communicate with the rest of the HVAC system. When you change the temperature on the thermostat, it sends a signal to your system to start up or shut down. If you opt for a smart thermostat, it can even let you remotely control the temperature of your home or office.

Once the warm or cool air is in your building, it’s pushed through a series of ducts and registers to reach each room. These ducts can be found in homes with central HVAC systems or in places where a ductless system has been installed. In either case, this air is filtered and cleaned, with excess humidity removed, before it is directed into space.

Cooling

As the name suggests, HVAC systems are designed to heat and cool indoor environments. They also ventilate the air and remove or add moisture as needed. They typically use ducts to move air and a conventional or smart thermostat to control temperatures.

Bright Hub Engineering explains that ventilation is the first element of any HVAC system, which brings in outdoor air through open windows and doors or a system of fans, blowers, filters, and ducts. Because modern construction methods create very tight homes and offices, mechanical ventilation is now necessary for most buildings.

Once inside a building, the air is drawn into an air handling unit (AHU) by a fan and flows over filters to remove dust, debris, allergens, bacteria, and other particles. The AHU then blows the air through ductwork, heating and cooling the space as it goes.

During the heating cycle, an air conditioner’s condensing coils absorb heat from indoor air. This warms the liquid refrigerant and allows it to evaporate in the evaporator. The heat from the evaporator is then transferred outdoors through the condensing coils, which cools the air.

Setting your thermostat to the cool setting signals the air conditioning unit to begin operating. The air conditioning unit removes humidity from the conditioned space, cooling it further and reducing its energy consumption in the process.

The entire process is controlled by either a conventional thermostat or a smart model that connects to your home’s Wi-Fi. The thermostat monitors temperature and other criteria; when conditions are met, it triggers the system to run. Smart thermostats can also send alerts when the filters need changing and offer other helpful features.

There are a number of other components that may be included in an HVAC system, such as ventilation systems that direct outdoor air back into a home or office, humidifiers and dehumidifiers to adjust the level of moisture in the air, and air purifiers that filter out spores, bacteria, viruses, and other minuscule contaminants. Your local professional will be able to help you decide which additional systems make the most sense for your specific needs.

Ventilation

Air moves through an HVAC system in one of two ways, depending on the type of unit. In most systems, the fan draws air through a network of ducts traveling through walls and floors. Other units, such as high-velocity HVAC systems, move air through insulated mini-ducts and inconspicuous vents.

In addition to warming or cooling indoor spaces, an HVAC system can improve air quality by filtering out noxious gases and pollutants and introducing fresh, clean air. These benefits of HVAC can improve occupant comfort, promote a healthier environment, and reduce energy costs by reducing the need for heating and air conditioning.

Unlike the heater that uses gas to warm air, an air conditioner uses electricity to cool it. As the fan draws air in, it passes over evaporator coils coated with refrigerant. The heat from the air causes the refrigerant to evaporate or turn into a gas. The vapor then moves into the compressor, which pressurizes it. The hot refrigerant then condenses into a liquid, which exits through the condenser, typically outside your home or business.

The cooled air then passes through the air handler in your home or business. The blower fan sends the cool air into ducts that run to each room of your house or office. Any noxious fumes are expelled through an exhaust pipe as the air circulates. In some cases, you may need to install a vent in the room where this process occurs to keep odors from wafting through other parts of the building.

An HVAC system can also help prevent air leaks. If the ducts aren’t sealed properly, conditioned air can escape. This is a major source of energy loss and can make your system less efficient. An experienced HVAC professional will help seal the ducts properly and perform annual inspections.

While HVAC systems come in a variety of shapes and sizes, they all operate similarly. They take in air, heat, or cool it and then blow it into an indoor space. An HVAC system can also include other components like air purifiers and dehumidifiers, which are designed to help improve indoor air quality. It can also incorporate a smart thermostat that lets users set different temperatures for individual rooms or zones in a home or business.

Controls

The function of HVAC systems is more than just warming or cooling a space; they can also improve air quality by removing dust and reducing moisture and provide ventilation by moving fresh air through ductwork throughout the building. In addition, modern HVAC equipment may be able to track energy usage and automate operation through smart thermostats.

There are a variety of types of HVAC systems that differ by size, location, and type of use. The most common are central systems that include a furnace, air handler, and fan, which can be used to heat or cool an entire home. Other systems include packaged units that combine heating and cooling elements into one unit, either indoor or outdoor. And, of course, there are window and through-the-wall air conditioning units.

These systems share a basic set of components that ensure the system works properly. These include sensing devices to compare actual states, such as temperature or humidity, with target states and relay switches that control the actuators (e.g., fans). A network infrastructure carries messages between the controllers and devices and provides power for the devices.

Most HVAC systems distribute the air they produce from the outdoors into occupied spaces by using blowers and a series of internal ducts. Some systems have separate ducts for each room. In other cases, a single blower circulates the air throughout space.

These systems often include filters to remove airborne particles and odors as they circulate. They can also remove excess humidity from the air to prevent condensation in ductwork and on ceilings, walls, and floors.

HVAC systems can be a significant investment and require regular maintenance to keep them working efficiently. When the time comes for repairs, look for a local professional specializing in your system. You can find them through an online search or by contacting your trusted provider of HVAC and home services, like Petro. It is a good idea to have an expert service your system each year before the heating season in late summer or early fall and again before the cooling season in late spring or early summer.