What Are the Main Elements of an HVAC System?

HVAC (heating, ventilation, and air conditioning) systems keep buildings and homes comfortable. The systems heat the interior of a building when the weather is cool and cool off interiors when temperatures outside climb. HVAC systems also filter the air and help control humidity levels.

If you’re interested in training to become an HVAC technician, one of the first things to know is the various parts of an HVAC system. Each component has a critical role to play in heating, cooling, and improving airflow in a building.

1. Blower Motor

HVAC systems are connected to a system of ducts that run throughout a building. Air travels along the ducts, exiting through registers into a building’s various rooms.

The blower motor plays an essential role in allowing air to move through the ducts. It’s connected to a fan that pushes heated or cooled air through the ducts. When heating a building, the blower kicks on after combustion begins and the air is warmed up. It turns off again once combustion stops.

Some HVAC systems have variable speed blower motors, which allow the system to regulate the flow of air throughout a building. Variable speed blower motors also help to regulate humidity levels inside a building.

2. Combustion Chamber

When an HVAC system is heating a home or building, it relies on the combustion chamber to warm the air. The combustion chamber is also called the burner.

Combustion chambers need two things to work properly: Fuel and air. When the system’s thermostat sends a message to the furnace that the temperature has dropped below the set level, oxygen enters the combustion chamber, where it combines with the fuel, such as natural gas. The fuel-air mixture ignites, producing heat. More fuel and air enter the chamber.

Older HVAC systems featured a pilot light, which burned continuously. Pilot lights weren’t energy efficient and also increased the risk of carbon monoxide poisoning. Newer systems feature electronic ignition, which only light when the system kicks on.

3. Condenser Coil

The condenser coil on an HVAC system plays a role in cooling the air inside a building. Part of the system’s AC, the condenser coil is located outside of the building. Its primary job is to release warmed air away from the system and building.

Refrigerant travels through the condenser coil in a warm, gaseous state. A fan blows over the coil, cooling the gas and compressing it so that it converts into a liquid. The warmth evaporates into the air outside the building while the cooled liquid travels through the system to the evaporator coil.

Condenser coils are sometimes called compressors.

4. Evaporator Coil

While the condenser coil is outside of a building and has the job of expelling warm air, the evaporator coil is located inside a building. It’s responsible for absorbing, and cooling, warm air.

Evaporator coils are usually made from a heat-conducting material, such as aluminum or copper. The coils are found in the air handler of an AC unit.

When the air conditioner turns on, the refrigerant travels into the evaporator coil. The warm air inside the home or building travels over the coil. The refrigerant inside the coil absorbs the heat from the air, so that cool air gets blown outward into the room. The coil can also absorb humidity from the air.

5. Heat Exchanger

The heat exchanger in an HVAC system transfers heat from one area to another. When the furnace component of an HVAC system kicks on, cold air enters the system.

The air blows over the heat exchanger, which is full of warmed gas. The warmth from the gas heats the air below it gets sent through the ducts to heat the building. Exhaust gases exit the heat exchanger and the building through a flue.

When an HVAC system cools the air, the evaporator coil and condenser coil act as the heat exchanger.

6. Thermostat

The thermostat is the device that controls the HVAC system. It measures the air temperature inside a building and sends a signal to the system to turn on when the temperature falls below a set point (for heating) or climbs above that point (for cooling).

The location of the thermostat matters, as it needs to accurately regulate air temperature. If the thermostat is located in a drafty area or too close to a vent or register, the temperature might fluctuate frequently, causing the system to work overtime.

If you’re interested in learning more about how HVAC systems work or want to pursue a career as an HVAC installer or maintenance technician, Orange Technical College offers two career certificates, HVAC 1 and HVAC 2. For more details on applying and what you can expect from the programs, contact us today.