The Air Handling Unit’s Functions (AHU)
- It distributes conditioned air to various conditioned locations.
- It regulates the temperature and adapts it to the requirements of conditioned spaces.
- It also regulates the amount of moisture in the air.
- It balances the air’s oxygen content.
- It manages the oxygen content of the air entering the conditioned chamber while allowing fresh air from the outside environment.
Various Air Handling Unit Classifications (AHU)
1. They can be categorized based on the way the components are arranged.
A horizontal unit is one in which every component is positioned at the same horizontal level.
Vertical Units are made up of all the parts stacked one on top of the other.
Horizontal Unit
Each unit is positioned at the same horizontal level in the case of the horizontal unit. It has both an inlet and an output. The air is the first condition and then goes through each component after entering from the entrance. Air finally emerges from the outlet.
For installation, these AHUs require additional floor space. The AHU needs a different floor area requirement for each of its parts. Therefore, horizontal units demand additional floor space. Vibration and noise must also be properly managed.
Vertical Unit
Vertical units have some or many of their components stacked on top of one another. The components are not all horizontally installed at the same level. As a result, this type of AHU requires less floor space than horizontal units. Vertical Units are typically installed in the AHU or fan rooms.
2. They can be categorized based on where the fan is about the cooling coil.
Both blow-through and draw-through AHUs are available.
Pull-through device
The supply fan is located after the cooling coil portion in the draw-through unit. The whole surface of the coil section is covered with evenly distributed conditioned air. Draw-through units are therefore chosen if an even air distribution is required.
These AHUs are the most popular since they operate more effectively. Although the Draw-through unit costs more than the Blow-through unit, this can be justified because of the latter’s lower efficiency.
Blowing-through device
The supply fan is placed in front of the cooling coil section in the blow-through device. Following the fan is where the cooling coil is located. Before the air enters the cooling coil section, the fan somewhat cools it. When air goes through the cooling coil in the Draw-through unit, it is first cooled. It is subsequently blasted into the ducts. The air temperature is reduced to some extent when it travels through the fan in the blow-through unit, though. The temperature is further lowered by passing through the cooling coil after that. Multi-zone AHUs frequently employ blow-through units.
3. An AHU can be categorized as a Single-zone AHU or a Multi-zone AHU depending on how many zones it serves.
Single-zone AHU
Single-zone As implied by its name, an AHU only serves one zone.
Given that they only serve one zone, they are small in size.
These AHUs have reduced capacity.
Numerous-zone AHU
Multiple zones are served by multi-zone AHU. As a result, these AHUs are expected to have a greater capacity. In comparison to single-zone AHUs, they are also larger.
4. The AHUs can be categorized as factory-fabricated or custom-built AHUs depending on how they were made.
AHU manufactured in a factory
As their name implies, they are made at manufacturing facilities. They are expertly constructed.
Because they are produced in large quantities and each component is carefully engineered, they are less expensive.
Built-to-order AHU
In terms of structure, component choice dimensions, etc, they offer more freedom.
AHUs are made on-site depending on the dimensions, weather, etc. when the on-site demand makes factory-built AHUs unavailable.
The cost of these AHUs is higher because each component is made to order.
5. The AHU can be categorized as either an Indoor AHU or a Rooftop AHU, depending on where it is located.
AHUs on roofs
They have roof mountings. They are constructed from sheets of aluminium or heavy gauge galvanized steel. They are also made to be weather and corrosion-resistant. Since they are situated on the roof, they are subjected to a variety of adverse weather conditions, such as rain, heat, and cold. So, when developing rooftop units, these considerations are taken into account. They consequently become exceedingly costly. Additionally, since the components are exposed to the environment, damage and failure are most likely to occur. As a result, the casing contains all of the components.
Inside AHUs
They are put in either the AHU or the fan room. These AHUs can also be hung on the ceiling if their size is very small.
In the nutshell
The central air conditioning system’s beating heart is the air handling unit (AHU). It gathers indoor and outdoor air, filters out dust and other debris, modifies the temperature and humidity, and then uses ducts to distribute cool, comfortable air conditioning into the rooms.
Above all else, it would be beneficial for every user to have a thorough understanding of the many varieties of AHU that are offered on the market.
