What is AHU? How It Works

In today's world, maintaining quality air has become increasingly challenging due to climate change and pollution. Every aspect of our environment directly impacts the air we breathe, making it essential for everyone to have access to good quality air.

Whether in commercial buildings, industrial spaces, or large residential complexes, this is where the AHU comes into play. AHUs are integral to effective climate control and, within the realm of HVAC systems, they play a crucial role in maintaining indoor air quality and comfort.

Let's dive in!

What is an AHU, and what is the full form of AHU

AHU stands for Air Handling Unit. It is a critical component of HVAC (Heating, Ventilation, and Air Conditioning) systems that is responsible for regulating and circulating air throughout a building.

Basically it collects outside and indoor air, filters out dust and particles, adjusts the temperature and humidity, and then supplies comfortable, refreshing air-conditioned air into rooms through ducts.

What are the parts of AHU? And how does AHU System works

The parts and operational process of AHU system is given below

1. Filtration Systems

One of the first components an AHU uses is the filtration system. As the AHU draws in air through the return ducts, the air passes through a series of filters designed to remove impurities such as dust, pollen, and other airborne particles. This process is crucial for maintaining a clean and healthy indoor environment.

2. Cooling Coils and Heating Elements

After filtration, the air moves on to the temperature control stage. Here, it encounters cooling coils or heating elements, depending on the building’s needs. The cooling coils reduce the air temperature during warmer months, while the heating elements warm the air during colder periods. This stage is vital for ensuring that the air is conditioned to the desired temperature before it is distributed throughout the building.

3. Control Dampers

within the AHU control the flow of air through the system. They regulate the distribution of air to different zones within the building, ensuring that each area receives the appropriate amount of conditioned air. Dampers are essential for maintaining balanced airflow and temperature control across various spaces.

4. Fans

Fans are responsible for moving the air through the AHU and into the supply ducts. They play a key role in ensuring that air is circulated efficiently throughout the building, reaching all designated areas.

5. Control Systems

The AHU’s control systems govern the overall operation of the unit. These systems monitor and adjust various parameters, such as temperature, humidity, and airflow, to ensure optimal performance. With precise controls, the AHU can respond to changing conditions and maintain a comfortable indoor environment.

What is AHU Type?

Air Handling Unit (AHU) types can be classified in various ways based on different criteria.

1. Configuration-based Classification

• Horizontal Unit: Components are placed horizontally, ideal for large spaces with ample floor area. Horizontal units are often more accessible for maintenance and repairs. They also allow for easier expansion or modification as needed.
• Vertical Unit: Components are stacked vertically, suitable for areas with limited floor space. Vertical units are ideal for high-rise buildings, indoor installations, or areas with restricted horizontal space. They also reduce the footprint, making them perfect for urban areas.

2. Fan and Coil Configuration

• Draw-Through Unit: Fan is located before the cooling coil, drawing air through the coil. This configuration allows for more even airflow and better dehumidification. It also reduces the risk of condensation and water damage.
• Blow-Through Unit: Fan is located after the cooling coil, blowing air through the coil. This configuration provides better filtration and reduced pressure drop. It also allows for easier access to the coil for cleaning and maintenance.

3. Zone Control Classification

• Single-Zone AHU: Serves a single temperature zone, ideal for small spaces or uniform cooling requirements. Single-zone AHUs are cost-effective and simple to install. They are suitable for residential, retail, or small office spaces.
• Multiple-Zone AHU: Serves multiple temperature zones, suitable for large spaces with varying cooling requirements. Multiple-zone AHUs offer greater flexibility and precise temperature control. They are ideal for commercial, industrial, or large office spaces with diverse cooling needs.

4. Manufacturing-based Classification

• Factory-Fabricated AHU: Pre-assembled and tested in a factory, offering quick installation and standardization. Factory-fabricated AHUs reduce on-site construction time and minimize errors.
• Custom-Built AHU: Built on-site or tailored to specific requirements, offering flexibility and unique design capabilities. Custom-built AHUs accommodate complex designs, unique space constraints, or special features. They require more time and expertise but provide a perfect fit for specific applications.

5. Location-based Classification

• Rooftop AHU: Installed on rooftops, ideal for saving indoor space and providing easy access for maintenance. Rooftop AHUs reduce noise pollution and minimize visual impact.
• Indoor AHU: Installed inside buildings, suitable for areas with limited outdoor space or specific architectural requirements. Indoor AHUs provide better protection from harsh weather conditions. They also reduce the risk of vandalism and unauthorized access.

Benefits of using an AHU system

• The AHU’s filtration system removes harmful particles, while the conditioning process adjusts the air’s temperature and humidity. This combination creates a more comfortable and sanitary indoor atmosphere.
• AHUs offer accurate control over indoor climate conditions, allowing for consistent temperature and humidity levels. This precise regulation helps in maintaining a stable and pleasant environment throughout the year.
• By optimizing temperature and humidity control, AHUs reduce the need for excessive heating or cooling. This leads to lower energy consumption and operational costs, making the system more cost-effective.
• The modular nature of AHUs allows for personalized solutions that fit various building sizes and requirements. This flexibility ensures that the system can be adapted to meet the specific needs of different applications, from commercial spaces to industrial facilities.

Disadvantages of AHU Systems

• If the air handling unit (AHU) malfunctions, the entire facility will lose air conditioning functionality.
• It is necessary to install multiple AHU units to provide backup and ensure continuous operation. But installing multiple AHU units can increase upfront costs.
• Multiple units also mean more components to maintain, potentially increasing maintenance time and costs.

How to maintain do servicing of an AHU system

1. Regular maintenance: Scheduled inspections, filter replacements, and cleaning are necessary to ensure the AHU system operates efficiently and effectively.
2. Prevent equipment malfunctions: Routine maintenance helps in identifying and addressing potential issues before they lead to system failures or malfunctions.
3. Call for qualified and experienced technicians: It is important to work with experienced professionals who have a thorough understanding of AHU systems to conduct inspections and resolve issues.
4. Have a maintenance plan: Following a detailed maintenance schedule helps in extending the lifespan of the AHU system and maintaining optimal performance.

Conclusion

AHUs systems are vital for maintaining indoor air quality and comfort in today’s challenging environment. They filter and condition air, regulate temperature and humidity, and improve energy. Regular maintenance, including inspections and timely repairs, is essential to keep AHUs running smoothly and effectively. By investing in an AHU system and following a maintenance plan, you ensure a healthier, more comfortable indoor environment while benefiting from energy savings and operational efficiency.