Attic-Fan Installation

Thanks to the low static pressure is involved (as a rule, less than 1/8. water), disk, and springs, the fans are normally used instead of the fan or posted types. It is important that the fans got quiet performance and potential to give at least 30 air changes per hour. For example, the house 10 000 ft3 content will need a fan capacity of 300 000 ft3/h or 5000 ft3/min give 30 air changes per hour.

Two main types of the attic fans for General use are boxed fans and centrifugal fans. The boxed-in fan is installed within an attic in a box or in a suitable housing, located directly above the center of the ceiling lattice or a bulkhead enclosing the attic stairs. This type of fan can also be connected through direct system of individual number of the lattice. Outside cold air coming through the window in the lower floor of the room, discharged in the attic space and burst out through the shutters, skylights, or screened holes under the roof.

Although ventilation installation of this type is simple enough, the actual decision about where to install the fan and where to ensure lattice for the passage of air through the house should be left for ventilation engineer. Installation of multiblade centrifugal fan shown in Fig. 3-30. On the suction side of the fan is connected to the exhaust ducts leading to the chambers, which are placed in the ceiling of the bedroom. Ventilation is carried out by admission of fresh air through the open window and through the suction side of the fan, the air is finally discharged through shutters, as shown.

Another installation is shown in Fig. 3-31. This fan centrifugal curved blade type, mounted on a light angle-iron frame that supports the fan wheel, shaft and bearings. Air inlet in this installation is placed close to a circular hole that is cut in an airtight Council section, which offers divide the attic space in the suction and discharge chamber. The air is admitted through open Windows and doors, and then build up to the attic stairs, through the fan in the discharge chamber.

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