What is an Air Handler or Air Handling Unit?

When it comes to heating, ventilation, and air conditioning (HVAC) systems, the air handler, also known as an air handling unit (AHU), plays a crucial role. Often unseen but vital to indoor comfort, an air handler is a key component that helps regulate and circulate conditioned air within buildings. In this article, we will explore what an air handler is, its components, and its significance in HVAC systems.

Understanding the Air Handler: An air handler, or air handling unit, is a device responsible for conditioning and distributing air within a building. It is typically located in a designated area, such as a mechanical room or basement, and connects to a network of ducts that distribute the conditioned air throughout the building.

Components of an Air Handler:

  1. Blower: The blower, or fan, is a critical component that circulates air through the system. It draws air in from the return ducts and pushes it through the HVAC system for conditioning.
  2. Heating and Cooling Elements: Air handlers are often equipped with heating and cooling elements, such as coils or heat exchangers. The heating elements can include electric coils or a hot water coil, while the cooling elements consist of refrigerant coils.
  3. Filters: Air handlers are equipped with air filters that help remove dust, pollutants, and allergens from the incoming air. These filters improve indoor air quality by capturing particles before the conditioned air is distributed throughout the building.
  4. Humidifiers and Dehumidifiers: In some cases, air handlers include humidifiers or dehumidifiers to regulate the humidity levels within a building. These components help maintain a comfortable and healthy indoor environment.
  5. Controls and Sensors: Modern air handlers incorporate advanced control systems and sensors to monitor and adjust various parameters. These may include temperature sensors, humidity sensors, pressure sensors, and airflow sensors. The controls ensure optimal performance and energy efficiency.

Importance of Air Handlers: Air handlers play a crucial role in maintaining a comfortable indoor environment in various settings, such as residential, commercial, and industrial buildings. Here are some key reasons why air handlers are significant:

  1. Air Distribution: Air handlers ensure that conditioned air is evenly distributed throughout the building. By controlling airflow and pressure, they help maintain consistent temperatures in different areas, eliminating hot or cold spots.
  2. Air Quality: Air filters in the air handler help remove contaminants, dust, and allergens from the incoming air, improving indoor air quality. This is especially important for individuals with allergies or respiratory conditions.
  3. Energy Efficiency: Advanced controls and sensors in modern air handlers enable precise monitoring and adjustment of airflow and temperature. This helps optimize energy consumption, leading to increased efficiency and cost savings.
  4. Climate Control: With integrated heating and cooling elements, air handlers provide the ability to regulate the temperature and humidity levels within a building. This allows occupants to maintain a comfortable environment regardless of external weather conditions.


Air handlers, or air handling units, are an integral part of HVAC systems. Their primary function is to condition and distribute air throughout a building. By regulating temperature, humidity, and air quality, air handlers play a crucial role in maintaining a comfortable and healthy indoor environment. Understanding the components and importance of air handlers helps us appreciate their significance in achieving optimal HVAC performance and occupant comfort.