How Does a Residential HVAC System Work?

How does an HVAC system work?

Heating, ventilation and air conditioning (HVAC) systems have many components and form an integral part of your home. Knowing each component and the different types available will give you insight into how the system works to keep your home heated or cooled.

How does an HVAC system work?

The three components of HVAC (heating, ventilation, and air conditioning) all work together to provide your home with the most ideal and comfortable temperature and air quality possible. When all parts of your HVAC system work together in harmony, you notice an improved air quality through the lack of heat, dust, odors, moisture, bacteria, and carbon dioxide in your air. 

Parts of the HVAC system and their functions

The following are different components of HVAC systems:


This is the most conspicuous part of the system, which people interact with the most. Often mounted on easily accessed walls, the thermostat can be set manually or automated to optimize the home’s temperature. When the ambient temperature becomes too hot or cold, the thermostat prompts the HVAC system to circulate air as required.


The furnace is a crucial element in the HVAC system and typically takes the most space. The furnace heats the air, which is delivered to different parts of the house through ductwork or piping. The heat source of the furnace could be solar energy, electric resistance, combustion, or heat pumps.

Evaporator coil

The evaporator coil cools down the air when the thermostat is set to a lower temperature. The cold air is then circulated throughout the house.

Condensing unit

This part is located outside the home and contains what is known as refrigerant gas. When the refrigerant is cooled, the condensing unit sends the liquid to the evaporator coil to be converted into a gas again.


These are the outlets through which cooled or heated air is delivered from the duct system to different parts of the house. They are usually located close to the ceiling with angle slats and fitted to send air downward. The vents must be open to ensure air delivery.

Refrigerant lines

These lines transfer refrigerant to the condensing unit in gas form. The gas is changed to a liquid state, then forwarded back to the evaporator coil.

Types of HVAC systems

Different types of HVAC systems have varying modes of operation. Homeowners must consider how the HVAC system works and their home structure to know which one would be the best fit in terms of function and efficiency.

Split system

This is the conventional type of HVAC system. It has indoor and outdoor units. Typically, it has an air conditioner to cool refrigerant outside the house and a furnace with a fan or coil indoors. They require ductwork to deliver air to different parts of the house.

Duct-free split system

This system is created to function without ductwork. Also called ductless mini-split, they are great for retrofitting homes without ducts or for rooms where installing distribution ductwork is not feasible.

Zoned systems

This system allows homeowners to cool or heat different parts of the house by controlling dampers or valves in the ductwork. The dampers allow selective blockage of airflow. They are cost-effective since they allow homeowners to decide which areas are heated or cooled.

Final note

Knowing how the system works will help when trying to pick the appropriate HVAC system. If you are considering a new HVAC system for your home, ensure you do your research first. Consult an HVAC professional for home inspection and HVAC system installation.

Request an appointment here: or call Bevills Plumbing, Heating & Air Conditioning at (325) 225-4115 for an appointment in our Abilene office.