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Difference Between AHU and FCU

ahu_bookAHU vs FCU

AHU and FCU are both included in the HVAC system. The latter is an acronym that describes multiple systems of heating, ventilating and air conditioning. AHU, completely known as air handling unit is different from FCU or the fan coil unit.

AHUs are usually connected to a central HVAC system whereas an FCU can function or be installed itself. Because of this, it is often the AHU that is used to ventilate an entire building whereas FCUs are used in smaller and often local spaces only. It is no surprise that AHU is the bigger HVAC system not to mention, the FCU is also regarded as the smaller version of the AHU. In this regard, the smaller FCUs can be called terminal units.

Because of the magnitude of the AHU system, it usually makes use of the air from the outside environment. Thus, it treats outside air and brings it inside the vicinity with the use of special ducts while an FCU system on the contrary just circulates the inside air. The latter usually does not have any duct system that’s why it is obviously smaller in size as previously mentioned. It is only composed of a simple coil and fan.

Ordinarily, AHUs have certain features that are not present in the FCU type. AHUs have several sections for reheating and even humidifying. FCUs don’t have sections such as these. Perhaps the only advantage that the FCU has over the AHU is that generally, FCUs can also handle water while the AHUs basically handle air.
Moreover, AHUs can have several fans or blowers installed in its system. Traditionally, the AHU’s blowers are placed at the point where the ducts originate or at the terminal end of the air handler unit. FCUs have a different approach to blowers. Because of its small size, their fans are usually placed within the same space as the unit itself. The result is a minor uncomfortable noise that can be heard within the vicinity. This could be regarded as the single most advantageous flaw of the FCU system.

1. AHU is generally a bigger system than FCU.
2. AHU is more complex than the FCU and that AHU are often used in bigger establishments or spaces.
3. The AHU system usually channels air through ducts whereas the FCU don’t have any ductworks.
4. AHU system treats outside air while FCUs basically recycle or re-circulates the air.
5. AHU have sections for reheating and humidifying whereas the FCU does not have any.
6. FCU are often observed to be noisier than the AHU.

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  1. Hi nice.

    AHU unit is very useful in commercial and industrial. Buildings and infrastructure in general, large central air-conditioning. And the central compressor and air-conditioning condenser unit. Evaporator connected to the furnace air-handling equipment. Included in the package, the whole system, often abroad, as the barn.

    Thanks for sharing.

  2. Air Handling Unit
    A.H.U is designed and manufactured to meet the international standard for air ventilation (fresh air/wet system) indoor air quality, comfort air conditioning and specialized application like clean room. A.H.U. for clean room consists of mixing chamber, pre filter, fine filter, coil section, fan section, optional pan humidifier and dehumidifier (strip heater). These are double screen section panels with aluminum hollow extruded profiles and thermoplastic, corner joints and omega section. Wet system like air washer is specially designed to meet saturation efficiency 90% and pressurization of 2-3 mm. of wg. All fans of A.H.U. (statically and dynamically balanced) are of SISW or DIDW range from 1000 to 60000 CFM and static pressure of more than 6” of WG.

  3. Can you please clarify on the matter that FCU doesn’t have any duct works…..

  4. Good day! Can they both be used in a centralized system? Can FCU replace AHU in a centralized system? We design restaurants in malls and i’ve been wondering why restaurants usually makes use of FCU’s while other stores only have grilles (diffusers?) on their ceiling. Thank you!

  5. Hello.
    whats the different between them in capacity range(i mean in CFM)

  6. What is the difference between DX air conditioning and package rooftop air conditioning

  7. A very useful information. Pl.suggest whether AHU or FCU requires fulls size access hatches (size as per AHU or FCU) or depends on the nfgrs. of the units?


  8. What is the normal rating of commercial HVAC chiller compressor.

  9. Ahu pless explane

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