- Fan Coil Unit (FCU)
- Air Handling Unit (AHU)
- Fresh Air Handling Unit (FAHU)
A Comparative Study
FCU has a combination of fan, filter, and air conditioning coils. At first, existing air from the room is pumped to the coil after proper filtration. The rotating fan cools down the temperature of the circulating air in the coil to the adequate requirement of the room. This cooled air is transferrred back to the room. It just recycles and re-circulates the air.
They are comparatively simple and less expensive. FCUs are opted for small tonnage capacity spaces such as rooms, offices, restaurants etc. High rise buildings employ AHU and FAHU along with FCU, as their demand for air conditioning is a bit more complex than small buildings.
AHU is an enhanced version of FCU. Along with the blowers and coils, it also has humidifiers, dampers, UV and noise filters, air purification filters, etc. AHU filters and conditions the air from outside the buildings or the indoor returned air. And they distribute the cooled air to the building room spaces.
Humidity monitoring is one of the major characteristics of AHU. Also, their tonnage capacity is higher than FCU and are employed for high rise buildings. But high rise buildings always require fresh air as the presence of oxygen is very necessary in the conditioned air. It is not healthy if it uses only the returned air from rooms for recirculation. Here comes the application of FAHU.
FAHU is similar to AHU except for the fact that they only use fresh air from the outdoor. The air recycling procedure happens only with FCU and AHU. But with FAHU, the return air will be extracted to the atmosphere. FAHU promises the oxygen content in the conditioned air to the building spaces. High rise medical buildings, and also both commercial and residential high rise premises employ FAHU in the HVAC systems.
