How Does the Central Heating System Work?

In residential and commercial buildings, central heating and cooling systems play a key role in maintaining comfortable indoor temperatures. They provide warmth during cold winter months and coolness in hot summers. 

Understanding how these systems work is essential for HVAC service technicians, who are responsible for installing, maintaining, and repairing them. A reputable HVAC program can equip you with the required skills to provide quality service in both residential and commercial settings.

Central Heating and Cooling Systems in Residential Buildings

In a residential building, a central heating and cooling system distributes conditioned air throughout the home using a series of ducts and vents. Let’s take a closer look at the heating and cooling process.


A central heating system in a residential building typically consists of a furnace or boiler, ductwork, and a thermostat. The process begins with the thermostat, which senses the indoor temperature. When the temperature falls below the set level, the thermostat sends a signal to the heating system to initiate the heating process.

In the case of a furnace, natural gas or oil is burned inside a combustion chamber, producing heat. The heat is then transferred to the air through a heat exchanger. The heated air is distributed throughout the building via ductwork and registers, providing warmth to each room.

On the other hand, a boiler heats water, which is then circulated through pipes to radiators or baseboard heaters, releasing heat into the rooms.


The central cooling system in a residential building typically involves an air conditioner, a blower, ductwork, and a thermostat. When the indoor temperature exceeds the desired level, the thermostat signals the cooling system to start.

The air conditioner extracts heat from the indoor air and transfers it outside, cooling the air in the process. The cool air is then blown through the ductwork and distributed throughout the building, maintaining a comfortable temperature.

Key Components of Central Heating and Cooling Systems in Commercial Buildings

In a commercial building, the central heating and cooling system is usually more complex and larger in scale. HVAC technicians should be familiar with the key components to ensure quality work. Here’s an overview:

  • Boilers or furnaces: These devices generate heat by burning fuel, such as natural gas, oil, or electricity. The heat produced is then transferred to the air or water, which is circulated throughout the building.
  • Chillers: Chillers work by cooling water, which is then circulated through the building to provide cooling. They can be air-cooled or water-cooled, depending on the system design.
  • Air handling units (AHUs): AHUs are responsible for conditioning the air processed in the HVAC system and distributing it throughout the building. They typically contain filters to remove debris and a blower to circulate air.
  • Ductwork: Ducts transport conditioned air from the AHUs to the various zones within the building.
  • Thermostats: These devices allow occupants to set the desired temperature and control the operation of the heating and cooling system.
  • Building management system (BMS): The BMS monitors and controls the entire system.

Common Types of Central Heating and Cooling Systems

There are several types of central heating and cooling systems used in residential and commercial buildings, including:

  • Forced air systems: These systems utilize ductwork to distribute heated or cooled air.
  • Heat pumps: Heat pumps can provide both heating and cooling by transferring heat from one location to another. They can be air-source, ground-source, or water-source, depending on where the heat is being transferred from.
  • Hydronic systems: Hydronic systems use hot or chilled water to heat or cool the building. The water is circulated through pipes and connected to radiators, fan coil units, or other heat exchangers.
  • Variable refrigerant flow (VRF) systems: VRF systems use refrigerant as the heat transfer medium and can provide simultaneous heating and cooling to different zones within the building.
  • Packaged rooftop units: These are mostly commercially used, combining heating and cooling functions into a single unit installed on the roof.

Begin Your HVAC Career with ETI’s HVAC/R Certification Program

If you have a passion for working with residential and commercial heating and cooling systems, choose ETI School of Skilled Trades. We offer effective training to become a certified HVAC service technician in just seven months.

With practical experience and industry-relevant knowledge, you’ll be well-prepared to start your rewarding career in the field of HVAC.

Enroll in our HVAC/R Certification Program today to take the next step in your career.

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