Fan Coil Unit

I'm not sure that terminology is the same everywhere. In my experience, AU (air unit) is synonymous with FCU (fan coil unit), "coil," or "evaporator." Such a unit usually controls (and is controlled by temperature), and the RH (relative humidity) of the room "floats" according to the coil size and the chilled fluid temperature within the tubes.

An AHU (air handling unit) typically incorporates more features, such as preheat, reheat, air mixing from external supply, or air exhaust. Such units can be capable of controlling (and being controlled by) both room temperature and RH.

A FCU is nothing more than a radiator; coils of tubing separated by fins in an enclosure. It is used with a supply of chilled water The FCU is inserted into the air stream of a ducted ventilation system. A thermostat control valve adjusts the flow of chilled water. An air handler (AHU) is a self contained unit that contains a FCU, a heat unit and a circulating fan or blower. It has connections for chilled water and hot water and is controlled by thermostatic valves. Both types are used onboard ships and can be used commercially.

Hi sir, depending on what you said may i say that FCU can be used insted of the split unit? and for what "must likely" AC loads can i use the FCU?

For small rooms ( such as rooms in hotels where each room has to be provided with independent On/Off control, prevention of transmission of noise, transmission of odors etc) for the indoor unit of the split a.c we have fan coil unit. IN FCU coil and fan unit all assembled in a compact casing. Electric two way solenoid valve or three way diverting valve is provided on the chilled water supply line to the coil. As I already mentioned we cannot carry out many psychrometric process in FCU due to its limited space. In such cases AHU is preferred. For example operation theater of a Hospital needs special air treatment ( HEPA filters), there FCU cannot be used. Generally it is used for small room comfort applications and not for process applications.

In tradesman language in America a fan coil usually can refer more to an individual room air conditioner, heating and/or cooling, as is seen in many hotel rooms and some offices.

An air handler might be something that is more used for distribution of air. It would likely have air conditioning features the same as a fan coil, but be connected to terminal units in the spaces served through ducts and connectors.

AHU - Air Handling Unit, FCU - Fan coil Unit.

Generally for higher capacities for more functions they named as AHU, For lower capacities for lesser function they named as FCU ( It may be Ductable split indoor unit or for Chill Water System).

Gererally the capacities given in terms of Air Flow rate( cfm, cmh, lps).

For example say less than 2000 cfm, named as FCU. It will vary depend upon the Manufactures.

A fan coil unit is actually an air handling unit although normally smaller in size. They both have a fan and coils inside a casing. Fan coil units are usually 1,000 CFM of air capacity and smaller but some can exceed this. Air handling units are available in about any capacity you might need and available in many configurations and supplied with many different attributes. The particular application being considered will determine which catalog you reach for.