Air Handling Unit (AHU) Fundamentals with Cooling Principle and its components

Summary

In this video, viewers are introduced to the basics of Air Handling Units (AHUs) and their temperature control principles. The video covers the two main types of AHUs: Fresh Air Handling Units (FAHU), which provide 100% fresh air from outside, and Recirculating Air Handling Units (RAHU), which recirculate indoor air. The components of an AHU, including the inlet damper, filtration units, cooling and heating coils, fan, and outlet dampers, are explained in detail. The video also discusses how temperature control is managed through automated systems like Building Management Systems (BMS), ensuring optimal comfort with minimal manual intervention.

Takeaways

• 😀 AHU stands for Air Handling Unit, a key component in HVAC systems used to control and circulate air in buildings.
• 😀 AHUs are connected to ventilation ductwork that distributes conditioned air throughout the building.
• 😀 There are two main types of AHUs: Fresh Air Handling Units (100% fresh air) and Recirculating Air Handling Units (circulates indoor air).
• 😀 Fresh Air AHUs intake air from outside, filter it, and condition it before supplying it to the building.
• 😀 Recirculating Air AHUs take air from inside the building, filter and condition it, and then return it to the building spaces.
• 😀 AHUs can be used individually or combined depending on the building's needs for air circulation and conditioning.
• 😀 Key components of an AHU include inlet dampers, filters, cooling and heating coils, fans, and outlet dampers.
• 😀 Inlet dampers regulate airflow into the AHU, while outlet dampers control the release of air into the ventilation ducts.
• 😀 The cooling coil in an AHU uses chilled water or refrigerant to cool the air and reduce humidity in the building.
• 😀 Heating coils provide warmth during colder weather, using either hot water or electric heating elements.
• 😀 The fan in an AHU pushes conditioned air into the building through ductwork. It can be equipped with Variable Frequency Drives (VFDs) to control the speed of the fan.
• 😀 Temperature control in an AHU is automated using the Building Automation System (BAS) or Building Management System (BMS), adjusting the cooling coil valve to maintain the desired temperature.

Q & A

What is an Air Handling Unit (AHU)?

An Air Handling Unit (AHU) is equipment used to control and circulate air to the building spaces as part of the HVAC system. It works to condition the air, ensuring it reaches the desired temperature and quality before being distributed throughout the building.

What are the two most commonly used types of AHUs?

The two most commonly used types of AHUs are the Fresh Air Handling Unit, which uses 100% fresh air from outside, and the Recirculating Air Handling Unit, which recirculates air from within the building.

What is the role of the Inlet Damper in an AHU?

The Inlet Damper serves as a separating device between the air intake duct and the AHU. It helps regulate the flow of air into the unit and ensures that the air entering is clean and free from dust.

Why is air filtration important in AHUs?

Air filtration is crucial in AHUs to prevent large particles like dust, hair, and fur from damaging the components. It helps ensure that the air being conditioned is clean and safe for the building occupants.

What are the two main types of filters used in AHUs?

The two main types of filters used in AHUs are the Pre-Filter, which blocks large particles, and the Bag Filter, which removes finer particles that the Pre-Filter cannot capture.

How does the Cooling Coil in an AHU work?

The Cooling Coil in an AHU uses chilled water or refrigerant gas to cool the air. As the hot air from outside passes over the coil, heat is transferred to the coil, cooling the air and reducing its temperature before it enters the building.

What is the function of the Heating Coil in an AHU?

The Heating Coil in an AHU is used to warm the air during cold weather conditions. It can use either a hot water system or electric heaters to increase the air temperature before it is circulated into the building.

What type of fan is used in AHUs and what is its purpose?

AHUs typically use fans with variable speeds, including single-speed, dual-speed, or fans equipped with Variable Frequency Drives (VFDs). These fans push the conditioned air into the building through the ventilation ductwork.

What is the purpose of the Outlet Damper in an AHU?

The Outlet Damper is similar to the Inlet Damper and allows for isolation of the AHU from the ventilation ductwork when it is not in use. It helps control the flow of air leaving the AHU.

How is temperature control achieved in an AHU?

Temperature control in an AHU is achieved by regulating the valve on the cooling coil. When the space temperature rises, the valve opens to allow more chilled water or refrigerant to cool the air. When the space is cooled sufficiently, the valve closes to maintain the desired temperature.