*B. Vertical air handling unit (vertical AHU)*

In vertical air handling units, the centrifugal fan is placed in a position above the cooling coil, heating coil, and humidifier as shown in **Figure 3**. Vertical air handling units are small in size and are low-capacity units, and thus they are installed in a small floor area of plant room [2].

safety measures must be taken before installing fresh air handling units on roofs due

In the blow-through units, supply air fan forces or pushes the air through the cooling coil (see **Figure 4**) to reduce the increase of supplied air temperature due to friction, and thus air can be cooled before being supplied to the various

In this type, the supply fan is placed after cooling coil (see **Figure 5**), heating coil, filter, and humidifier, and thus air is pulled by the supply fan. This system is commonly used as filters and coils which require small air speed and larger ducts

*A schematic diagram of blow-through type of air handling unit. Redrawn with modification from [2].*

*2.1.1.3 Classification of air handling unit based on supply air fan placement*

*A schematic diagram of vertical air handling unit. Redrawn with modification from [2].*

*Central Air Conditioning: Systems and Applications DOI: http://dx.doi.org/10.5772/intechopen.89455*

to their large weights [2].

*A. Blow-through units*

*B. Draw-through units*

zones [2].

**Figure 4.**

**5**

**Figure 3.**
