Components of Fan-Coil Unit

Components of Fan-Coil Unit Points : Components of Fan-Coil Unit, Fan, Fan Motor, Coil, Filters A fan-coil unit or a fan coil is a terminal unit installed directly inside the conditioned space or in the ceiling plenum just above the conditioned space. A fan-coil unit includes a small motor driven centrifugal fan or two small centrifugal fans connected in parallel a finned coil a filter and outer casing and controls sometimes a cooling coil a heating coil may be connected in series along the airflow as show in figure. A fan-coil unit can be a horizontal unit installed inside the ceiling plenm a vertical unit mounted on the floor under the windowsill (fig le) or a stack unit installed vertically along the two side of the window. Vertically and stack unit are usually used to offset the cold draft on the inner surface of window glass or on the external wall during cold weather. Cold draft often flows downward along the glass because it is heavier than the surrounding air. Warm air discharged from a fan coil during winter heating raises the inner surface temperature of window glass. Horizontal and vertical fan-coil unit are fan-coil unit are available in standard size 02,03,04,06,08,10,12,16 and 20 size 02 means a nominal flow rate of 200 cfm (0-1 m³ is) 04 means 400 cfm (02 m3Is) and so on. Fan Double-width, doubIe-inlet, forward-curved centrifugal fans are usually used because of their compact size and lower level. The fan wheels are usually made of aluminum, or galvanized steel with a diameter less than 10 inches (250 mm) in most cases fan housings are die-formed with integral scrolls and inlets. Fan Motor Permanent-split capacitor (PSC) motor and shaded-pole (SP) motors are used as in sec.26.4; .PSC motors have an efficiency of 55 to 70 percent which is considerably higher than that of sp motors, which have 30 to 40 percent efficiency. Two speed high-low switches or three-speed high-medium —low switches are used to vary the fan thermal overload protector, periodic oiling of the bearing (twice per year) is required. Coil Coils are usually made from copper tubes and aluminum fans. Cooling heating coil usually have two three or four rows of fins, depending on the coil on the coil’s cooling capacity and the sensible heat ratio of the cooling and dehumidifying process. SHR, two-row coil and widely used four-row coil have a greater dehumidifying capacity. Usually, there is only one coil for both heating and cooling. A separate electric heating coil is some times used with two-stage step control in location where the heating season is short or energy rates are low in winter. Manual air vents are installed to prevent the formation of air pockets inside the water circuit. A galvanized — steel pan with an insulating liner Id often used to drain the condensation on the fan-coil unit. To reduce the air side pressure loss, the face velocity of the air flowing through the coil is usually from 200 fpm (1m/s) to300fpm (1.5m/s). Filters Usually low-efficiency low-pressure drop permanent filter are used. They are easy to clean and replace periodically sometimes-disposable low efficiency fiberglass are used.