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Operation of a Forced Air System: Efficient Cooling and Heating


Operation of a Forced Air System: Efficient Cooling and Heating


Did you know that the same system that keeps you warm in the winter, is the same one that keeps you cool in the summer? Forced air systems are often thought of as associated with the heating of buildings through equipment such as heat pumps and furnaces. However, this article will explore their use as both heating and cooling systems. Their versatility is just one of the many advantages of forced air systems. Today, people typically spend about 90% of their time indoors, so maintaining a comfortable indoor environment year-round is incredibly important to boosting our productivity, improving sleep quality, and so much more. Understanding how your HVAC system operates, and its potential could be the key to unlocking these advantages. Whether you’re a homeowner looking to optimize your energy usage, or a building manager striving to maintain an efficient and effective climate control system, grasping the nuances of forced air systems can offer significant benefits.

This blog will delve into the intricate workings of forced air cooling systems, highlighting the differences between central air and forced air setups and their essential components. We will explore the many benefits of a properly set up and maintained forced air system while addressing common challenges and maintenance tips to ensure your system operates at peak performance. 

What’s the Difference Between a Central Air System and a Forced Air System?

Central air and forced air systems are often confused or used interchangeably. But this is erroneous. Central air specifically denotes the air conditioning unit that cools the air in an indoor space. It operates on a closed loop of refrigerant that cycles through the system, providing consistent, cool air during hot weather. As for forced air, this HVAC term refers to systems that distribute air—whether heated or cooled—throughout the building via ducts and vents. When installing a new HVAC system, it’s common to replace or install a central air conditioning unit and connect it to an existing forced air distribution system.

What is a Forced Air System?

Most homes and buildings these days use a forced air system, which is an integral part of any HVAC setup. It uses a blower (or air handler) to “force” either heated or cooled air through a network of ducts that comes out through vents (or registers) in rooms. This system heats up or cools down indoor spaces depending on the requirements of the season. These days, not only can forced air systems control the general temperature throughout an entire building; but temperatures can also be made to vary throughout a building or home depending on demand. This is called demand-controlled ventilation (DCV). If you were looking to implement DCV, you would need to capture temperature and occupancy data using sensors (wired or wireless) in whichever rooms you desired to individually target. These sensors would send data to the smart HVAC system, and hot or cool air would be distributed to occupied rooms depending on the desired temperatures set on the thermostat. In other words, energy would not be used to heat or cool unoccupied rooms, reducing operating costs for building managers and homeowners alike. 

Forced Air System Benefits

Forced air systems offer several advantages. 

  • Efficient Air Distribution: These systems ensure even temperature distribution throughout spaces, eliminating hot and cold spots. This is assuming vents in rooms are not blocked, and ducts are clear. 
  • Air Filtration: They improve indoor air quality by filtering and purifying the air, reducing allergens, dust, and germs. To maintain good air quality in a space, be sure to clean air filters every few months, or replace them when necessary. 
  • Energy Efficiency: Modern forced air systems, especially those with smart controls and demand-controlled ventilation, can significantly enhance energy efficiency.
  • Comfort: With the ability to quickly adjust temperatures, these systems maintain a comfortable indoor environment year-round.


Challenges and Maintenance

Despite their benefits, forced air systems do come with challenges:

  • Ductwork Maintenance: Ducts can accumulate dust and debris over time, necessitating regular cleaning to maintain air quality and system efficiency.
  • Noise: Some systems can be noisy, particularly if the ducts or blowers are not properly maintained.
  • Air Leakage: Poorly sealed ducts can lead to air leakage, reducing the system’s overall efficiency and increasing energy costs.
  • Regular Filter Replacement: Air filters need to be cleaned or replaced several times a year to ensure optimal performance and air quality. Ask an HVAC professional for recommendations on the best air filters to use in your forced air system. 


How a Forced Air System Works

A forced air system operates through a series of coordinated steps:

  1. Temperature Control: The thermostat sets the desired temperature, signaling the system to either heat or cool the air.
  2. Air Handler Activation: The system starts with the air handler, which forces air through the ductwork.
  3. Air Circulation: The blower moves the heated or cooled air through ducts and into rooms via registers (vents).
  4. Return Air: Air is returned to the system through return ducts, where it is filtered, reconditioned, and recirculated.
  5. Vent Control: A system of vents, blowers, and dampers allows the occupant of each room to control the amount of warm or cool air.

How a Forced Air System Works

Components of a Forced Air System

The primary components of a forced air system include:

  • Air Handler: Contains the blower and other essential components to move air through the system.
  • Ductwork: Network of ducts that distribute air throughout the building.
  • Registers and Vents: Openings that allow conditioned air to enter rooms and return to the system.
  • Thermostat: Controls the system by setting the desired temperature.
  • Heat Exchanger: Heats the air in the furnace before it is distributed (in heating mode).


The Components of a Forced Air System Associated with Cooling, and How They Work

When it comes to cooling, several specific components come into play:

  • Outdoor Unit: This includes the condenser and compressor. The condenser releases heat from the refrigerant, while the compressor pumps the refrigerant through the system.
  • Evaporator Coil: Located inside the air handler, the evaporator coil absorbs heat from the indoor air, cooling it as it passes over the coils.
  • Blower: The blower fan pushes the cooled air through the ducts and into the living spaces.
  • Refrigerant Lines: These lines carry refrigerant between the indoor and outdoor units, facilitating the heat exchange process.


Efficiency Ratings for Forced Air Systems in Ontario

Efficiency is a crucial factor for any HVAC system, particularly in regions like Ontario where energy costs and environmental regulations are stringent. Efficiency ratings for forced air systems are measured using several metrics:

  • SEER (Seasonal Energy Efficiency Ratio): Higher SEER ratings indicate more efficient systems. Heat pumps should have at least a 6.8 HSPF rating, and a minimum 13 SEER rating is required in Canada today for new units. However, a higher SEER rating is ideal. To be considered highly efficient, a unit should have a SEER rating of 18 or higher. Some heat pumps have ratings above 20.


  • AFUE (Annual Fuel Utilization Efficiency): AFUE is a rating that reflects how efficiently a gas furnace converts fuel to energy. The higher the AFUE, the more efficient the unit is at heating your home. 
  • ENERGY STAR Certification: Many forced air systems carry the ENERGY STAR label, indicating they meet strict efficiency guidelines set by the U.S. Environmental Protection Agency and the Department of Energy, which are also recognized in Canada.



A forced air cooling and heating system is a versatile and efficient way to maintain comfortable indoor temperatures year-round. Understanding the components and operation of these systems can help homeowners and building managers make informed decisions about installation, maintenance, and upgrades. Regular maintenance, such as cleaning or replacing air filters and ensuring ducts are clean, is essential to keep the system running efficiently. For those in Ontario and beyond, considering the efficiency ratings and opting for ENERGY STAR-certified equipment can lead to significant energy savings and a reduced environmental footprint. Whether you’re looking to cool your home during the hot summer months or maintain a consistent climate in your commercial building, a well-maintained forced air system is key to achieving optimal comfort and efficiency. 

Contact TRI-AIR SYSTEMS today to find out more about forced air systems, and how we can help keep your HVAC system running smoothly.