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What is an Air Handler?

Air handlers are fundamental components of HVAC systems used in commercial settings, responsible for regulating air flow, temperature, humidity, and air quality within a building.

air handler with text 'what is an air handler'

These units play a crucial role in distributing conditioned air throughout the premises, ensuring a comfortable and healthy indoor environment for occupants.

Air Handler Definition and Purpose:

  • Air handlers, also known as air handling units (AHUs), are devices designed to circulate and condition air as part of a heating, ventilation, and air conditioning (HVAC) system.

  • The primary purpose of an air handler is to facilitate the exchange of air between the interior and exterior of a building while regulating its temperature and humidity levels.

  • Air handlers work in conjunction with other HVAC components such as chillers, boilers, and ductwork to deliver conditioned air to various zones or spaces within a commercial building.

Importance of an AHU in Commercial HVAC Systems:

  • In commercial settings, where large spaces and diverse occupancy demands are common, air handlers play a critical role in maintaining indoor comfort and air quality.

  • By efficiently distributing conditioned air, air handlers help regulate temperature fluctuations, control humidity levels, and mitigate indoor pollutants, creating a conducive environment for occupants and activities.

  • The versatility and customization options offered by air handlers allow businesses to tailor their HVAC systems to meet specific comfort and operational requirements, enhancing productivity and occupant satisfaction.

Now that we have set the stage, lets explore the air handlers' functionality, components, applications, and benefits within commercial HVAC systems.


components of an air handling unit AHU

Components of an Air Handler

Air handlers consist of several essential components that work together to circulate, filter, heat, or cool air as required by the HVAC system.

Understanding these components is crucial for comprehending how an air handler functions within a commercial HVAC system.

Air Intake:

The air intake section of an AHU is where outside air or return air from the building is drawn into the unit for conditioning.

It typically includes dampers and louvers to control the flow of air, ensuring an adequate supply for ventilation and comfort.


Filters within the AHU remove airborne particles, pollutants, and contaminants from the incoming air stream.

Depending on the requirements, filters may range from basic particulate filters to high-efficiency filters capable of capturing fine particles, allergens, and pathogens.

This helps improve indoor air quality, thereby creating a healthier and more comfortable environment for building occupants.

Regular filter maintenance is essential to ensure optimal air quality and prevent the buildup of debris that could hinder airflow and strain the system.

Blower Motor/Fan:

The fan in an AHU is an electromechanical system responsible for circulating air through the unit and into the ductwork.

It creates the necessary airflow to distribute conditioned air throughout the building.

Variable-speed blower motors offer flexibility in adjusting airflow rates to match varying demand levels, enhancing energy efficiency and comfort control.

Heat Exchangers:

Heat exchangers in an AHU transfer thermal energy between two fluid streams, typically air and a cooling or heating medium.

They ensure precise temperature control by either removing heat from or adding heat to the air as required to maintain comfort conditions.

Cooling Coil:

The cooling coil, also known as the evaporator coil, is a heat exchanger that cools the air passing through it.

It removes heat from the air, causing moisture to condense and be collected in a drain pan.

This process lowers the air temperature and reduces humidity levels for improved comfort.


Silencers are coatings/acoustic devices installed within the AHU to reduce noise generated by the fan and airflow.

They consist of sound-absorbing materials and baffles designed to attenuate sound levels, ensuring quiet operation of the HVAC system.


Plenums are chambers or compartments within the AHU where air is collected, mixed, or distributed.

They ensure uniform airflow distribution and pressure balance throughout the unit, optimizing performance and efficiency.

Ductwork Connections:

Air handlers are typically connected to ductwork that distributes conditioned air to different zones or rooms within a building.

Supply ducts carry conditioned air from the air handler to the occupied spaces, while return ducts transport stale air back to the unit for reconditioning.

Proper ductwork design and sizing are critical to achieving efficient airflow distribution and maintaining consistent comfort levels throughout the building.


the steps of how an air handler works - air intake, conditioning, filtering, and blower operation

How an Air Handler Works

Understanding the operation of an air handler is essential for grasping its role in commercial HVAC systems.

Air Circulation Process:

  1. Air Intake: The air handler draws indoor air through return ducts, pulling it into the unit for conditioning.

  2. Conditioning: Inside the air handler, the air passes over the evaporator coil, where it is cooled or heated, depending on the system's mode.

  3. Filtering: As the air flows through the unit, it passes through filters that capture dust, allergens, and other airborne particles, improving indoor air quality.

  4. Blower Operation: The blower motor propels the conditioned air through the supply ducts, distributing it to different areas of the building.

Cooling Functionality:

  • During the cooling mode, the evaporator coil extracts heat from the indoor air, causing moisture to condense and collect in a drain pan.

  • The cooled and dehumidified air is then circulated back into the building, reducing indoor temperatures and maintaining comfort levels.

Heating Functionality:

  • In heating mode, the air handler reverses the refrigerant flow direction, allowing the evaporator coil to act as a heat exchanger.

  • Heat absorbed from the outdoor air or generated by electric resistance coils is transferred to the indoor air passing over the coil, raising its temperature.

Humidity Control:

  • Air handlers play a crucial role in regulating indoor humidity levels by removing excess moisture during the cooling process.

  • The condensate collected in the drain pan is typically drained away from the unit to prevent moisture buildup and maintain a comfortable humidity level indoors.

Air handlers primary functions are to condition and distribute air within commercial spaces, ensuring optimal comfort and air quality for occupants.


installation and integration of an air handler (AHU)

Air Handler Installation and Integration

Proper installation and integration of air handlers are essential for ensuring efficient operation and optimal performance within commercial HVAC systems.

This section elaborates on the key considerations involved in installing and integrating air handlers into commercial spaces.

Placement within Commercial Spaces:

Strategic Location:

Air handlers should be strategically placed within the building to optimize airflow distribution and minimize ductwork lengths.


Accessibility for maintenance and servicing purposes is crucial when selecting the installation location.

Noise Considerations:

Placement should also take into account noise levels to minimize disruptions to occupants and neighboring areas.

Ductwork Design and Configuration:

Sizing and Layout:

Proper sizing and layout of ductwork are essential to ensure adequate airflow distribution and minimize pressure losses.

Sealing and Insulation:

Ductwork should be properly sealed and insulated to prevent air leakage and maintain energy efficiency.

Zoning Considerations:

Zoning capabilities of air handlers should be taken into account when designing ductwork to accommodate different comfort zones within the building.

Electrical and Control System Connections:

Electrical Requirements:

Proper electrical connections must be established to power the air handler and its components safely.

Control Integration:

Integration with building automation systems (BAS) or HVAC control systems is essential for seamless operation and monitoring of the air handler.

Sensor Placement:

Placement of temperature, humidity, and airflow sensors should be carefully considered to ensure accurate monitoring and control of the system.

Compatibility with Other HVAC Components:

Chiller/Boiler Compatibility:

Air handlers should be compatible with chillers or boilers used for heating or cooling purposes to ensure efficient operation.

Filter Selection:

Selection of compatible filters is crucial for maintaining indoor air quality and preventing airflow restrictions within the air handler.

Condensate Drainage:

Proper drainage connections should be established to remove condensate collected within the air handler efficiently.


maintenance and servicing for air handler (AHU)

Air Handler Maintenance and Servicing

Regular maintenance and servicing are essential for ensuring the longevity, efficiency, and reliability of air handler units in commercial HVAC systems.

This section elaborates on the importance of maintenance and provides guidelines for servicing air handlers effectively.

Regular Filter Replacement:


Filters should be checked regularly and replaced as needed to maintain optimal airflow and indoor air quality.

Filter Types:

Selecting the appropriate filter type based on the application and environmental conditions is crucial for effective filtration.


Filters can also be cleaned if reusable, but replacement is often recommended for maximum efficiency.

AHU Cleaning and Inspection Procedures:

Coil Cleaning:

Regular cleaning of evaporator and condenser coils is essential to prevent dirt buildup and maintain heat transfer efficiency.

Fan and Blower Maintenance:

Inspecting and lubricating fan bearings, belts, and pulleys can help prevent mechanical failures and ensure smooth operation.

Ductwork Inspection:

Periodic inspection of ductwork for leaks, obstructions, or damage is necessary to maintain proper airflow and system performance.

Motor and Belt Maintenance:

Belt Tension:

Checking and adjusting belt tension ensures optimal performance and prevents premature wear of motor and blower components.

Motor Lubrication:

Lubricating motor bearings and other moving parts helps reduce friction and prolongs the lifespan of the motor.

Motor Inspection:

Regular inspection of motor components for signs of wear or damage is crucial for identifying potential issues early and avoiding costly repairs.

Troubleshooting Common Issues:

Airflow Restrictions:

Addressing airflow restrictions caused by dirty filters, blocked ductwork, or malfunctioning components is essential for maintaining system efficiency.

Temperature Fluctuations:

Identifying and resolving issues related to temperature inconsistencies, such as faulty thermostats or refrigerant leaks, helps ensure occupant comfort.

Noise or Vibration:

Investigating and addressing sources of excessive noise or vibration, such as loose components or imbalanced fan blades, improves system performance and reduces noise levels.


benefits of an air handling unit (AHU) in commercial setting

Benefits of Air Handlers in Commercial Settings

Air handlers offer numerous advantages when integrated into commercial HVAC systems, enhancing comfort, efficiency, and indoor air quality for building occupants.

Customized Comfort Control:

Zoning Capabilities:

Air handlers allow for zoning, enabling individual temperature control in different areas of a commercial building.

Precision Temperature Regulation:

By distributing conditioned air effectively, air handlers maintain consistent temperatures throughout the building, ensuring occupant comfort in diverse spaces.

Improved Indoor Air Quality (IAQ):

Effective Filtration:

Equipped with filters, air handlers capture and remove airborne particles, allergens, and contaminants, enhancing IAQ and promoting a healthier indoor environment.

Humidity Control:

Air handlers help regulate indoor humidity levels, reducing the risk of mold growth, moisture-related issues, and discomfort for occupants.

Energy Efficiency and Cost Savings:

Optimized Performance:

Properly maintained air handlers operate efficiently, reducing energy consumption and lowering utility costs for commercial facilities.

Variable-Speed Technology:

Advanced air handler models feature variable-speed blower motors, which adjust airflow based on demand, maximizing energy efficiency and reducing overall operational expenses.

Flexibility and Adaptability:

Compatibility with Various Systems:

Air handlers can be integrated with different HVAC components, such as chillers, boilers, and ductwork, providing flexibility in system design and adaptation to specific building requirements.


As commercial spaces evolve or expand, air handlers offer scalability, allowing for system upgrades or modifications to accommodate changing needs and occupancy patterns.

Quiet Operation and Minimal Footprint:

Low Noise Levels:

Modern air handlers are designed for quiet operation, minimizing disruptions to occupants, and enhancing workplace productivity.

Space-Saving Design:

Compact and modular air handler units optimize space utilization, making them suitable for installation in various commercial environments with limited space availability.


Applications of Air Handlers in Commercial Buildings

Air handlers serve diverse roles in commercial HVAC systems, catering to various heating, cooling, and ventilation requirements within different types of commercial facilities.

Office Buildings:

Temperature Regulation:

Air handlers maintain comfortable temperatures throughout office spaces, ensuring a conducive working environment for occupants.

Indoor Air Quality:

By filtering and circulating fresh air, air handlers help improve indoor air quality, reducing pollutants and enhancing occupant health and productivity.

Retail Stores and Shopping Centers:

Climate Control:

Air handlers regulate indoor temperatures in retail environments, ensuring optimal shopping experiences for customers and staff.

Humidity Management:

Effective humidity control provided by air handlers helps preserve product quality and prevents moisture-related issues in retail spaces.

Healthcare Facilities:

Sterile Environments:

Air handlers equipped with high-efficiency particulate air (HEPA) filters maintain sterile conditions in healthcare settings, minimizing the spread of airborne contaminants and infections.

Temperature and Humidity Control:

Precise temperature and humidity control provided by air handlers create comfortable and safe environments for patients, staff, and sensitive medical equipment.

Hotels and Hospitality:

Guest Comfort:

Air handlers play a vital role in ensuring guest comfort by maintaining consistent temperatures and optimal indoor air quality in hotel rooms and common areas.

Energy Efficiency:

Energy-efficient air handlers help hotels reduce operational costs while providing superior guest experiences.

Data Centers and Server Rooms:

Temperature Control:

Air handlers regulate temperatures in data centers and server rooms, preventing equipment overheating and ensuring uninterrupted operations.

Air Filtration:

Advanced filtration systems in air handlers remove dust and particulates, protecting sensitive IT equipment from contamination and damage.

These applications highlight the versatility and importance of air handlers in meeting the diverse heating, cooling, and ventilation needs of commercial buildings across various industries, contributing to occupant comfort, operational efficiency, and environmental control.


Considerations for Selecting an Air Handler

Choosing the right air handler is crucial for achieving optimal performance and efficiency in commercial HVAC systems.

Capacity and Size Requirements:

Building Size:

Determine the appropriate capacity of the air handler based on the size and layout of the commercial facility to ensure sufficient airflow and temperature control.

Load Calculation:

Conduct a load calculation to assess heating and cooling requirements accurately, considering factors such as occupancy, equipment heat gain, and insulation levels.

Energy Efficiency and Operating Costs:

Energy Efficiency Ratings:

Evaluate the energy efficiency ratings of air handlers, such as SEER (Seasonal Energy Efficiency Ratio) and EER (Energy Efficiency Ratio), to choose models that offer optimal energy savings.

Variable-Speed Technology:

Consider air handlers with variable-speed motors, which adjust airflow based on demand, maximizing energy efficiency, and reducing operating costs.

Installation and Integration:

Space Constraints:

Select air handler models that can be easily installed within the available space in the building, considering factors such as unit dimensions and access for maintenance.

Compatibility with Existing Systems:

Ensure compatibility with existing HVAC components, such as ductwork, chillers, and controls, to facilitate seamless integration and system operation.

Air Quality and Filtration:

Filtration Efficiency:

Assess the filtration capabilities of air handlers, considering factors such as MERV (Minimum Efficiency Reporting Value) ratings, to ensure effective removal of airborne contaminants and allergens.

IAQ Features:

Look for air handlers with IAQ features, such as UV germicidal lamps and HEPA filters, to enhance indoor air quality and promote a healthier environment for occupants.

Maintenance and Serviceability:


Choose air handler models that are designed for easy access and maintenance, with features such as hinged access panels and removable filters.


Consider the availability of replacement parts and access to technical support when selecting air handlers to facilitate timely maintenance and repairs.

Budget and Long-Term Costs:

Initial Investment:

Compare the initial cost of air handlers with their long-term energy savings and operational efficiency to determine the best value for your budget.

Total Cost of Ownership:

Factor in ongoing maintenance, repair, and energy costs to assess the total cost of ownership over the lifespan of the air handler.

Warranty and Support:

Warranty Coverage:

Review warranty terms and coverage offered by manufacturers to protect against defects and ensure peace of mind.

Technical Support:

Choose reputable manufacturers that provide reliable technical support and assistance to address any issues or concerns with the air handler.

These considerations provide businesses with valuable insights into the factors that influence the selection of air handlers for commercial HVAC systems, enabling them to make informed decisions that meet their specific requirements and budgetary constraints.


Conclusion: The Role of Air Handlers in Commercial HVAC Systems

Air handlers play a crucial role in maintaining comfort, indoor air quality, and energy efficiency within commercial buildings.

A. Comfort and Indoor Air Quality:

  • Air handlers ensure consistent temperatures and humidity levels, creating comfortable indoor environments for building occupants.

  • Advanced filtration systems remove airborne contaminants and allergens, enhancing indoor air quality and promoting a healthier workplace.

B. Energy Efficiency and Cost Savings:

  • Energy-efficient air handlers help reduce operational costs by minimizing energy consumption and maximizing system efficiency.

  • Variable-speed technology and optimized airflow control contribute to significant energy savings over the lifespan of the HVAC system.

C. Versatility and Adaptability:

  • Air handlers offer flexibility in system design and integration, accommodating various heating, cooling, and ventilation requirements in commercial settings.

  • Modular and scalable designs allow for easy expansion or modification of HVAC systems to meet evolving building needs and occupancy patterns.

D. Reliability and Performance:

  • Well-maintained air handlers ensure reliable and consistent performance, minimizing downtime and disruptions to business operations.

  • Robust construction and quality components contribute to the longevity and durability of air handler units, providing long-term value and peace of mind for building owners and facility managers.

E. Environmental Impact:

  • By optimizing energy usage and reducing greenhouse gas emissions, air handlers contribute to environmental sustainability and corporate responsibility initiatives.

  • Advanced technologies and eco-friendly refrigerants further enhance the environmental performance of commercial HVAC systems.

F. Future Trends and Innovations:

  • Embracing these innovations ensures that commercial HVAC systems remain at the forefront of sustainable building practices and energy management strategies.

Air handlers are indispensable components of modern commercial HVAC systems, offering a wide range of benefits that contribute to occupant comfort, operational efficiency, and environmental sustainability.

Understanding the role of air handlers empowers businesses to make informed decisions when designing, installing, and maintaining HVAC systems for their commercial facilities.

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