Category Archives for Ventilation Requirements

HVAC Attic Fan Operation

The routine of operation to secure the best and most efficient results with an attic fan is important. Atypical operating routine might require that, in the late afternoon when the outdoor temperature begins to fall, the windows on the first … Continue reading

04. January 2011 by admin
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HVAC Attic-Fan Installation

Because of the low static pressures involved (usually less than 1/8 in. of water), disk or propeller fans are generally used instead of the blower or housed types. It is important that the fans have quiet operating characteristics and sufficient … Continue reading

04. January 2011 by admin
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HVAC Fan Operation

Fans may be centrally located in an attic or other suitable space (such as a hallway), and arranged to move air proportionately from several rooms. A local unit may be installed in a window to provide comfort cooling for one … Continue reading

04. January 2011 by admin
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HVAC Fan Applications

The numerous applications of fans in the field of air-conditioning and ventilation are well known, particularly to engineers and air-conditioning repair and maintenance personnel. The various fan applications are as follows: ? Exhaust fans ? Circulating fans ? Cooling-tower fans … Continue reading

04. January 2011 by admin
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HVAC Fan Selection

Most often, the service determines the type of fan to use. When operation occurs with little or no resistance, and particularly when no duct system is required, the propeller fan is commonly used because of its simplicity and economy in … Continue reading

04. January 2011 by admin
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HVAC Fan Drive Methods

Whenever possible, the fan wheel should be directly connected to the motor shaft. This can usually be accomplished with small centrifugal fans and with propeller fans up to about 60 in. in diameter. The deflection and the critical speed of … Continue reading

04. January 2011 by admin
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HVAC Fan or Blower Horsepower Requirements

The horsepower required for any fan or blower varies directly as the cube of the speed, provided that the area of the discharge orifice remains unchanged. The horsepower requirements of a centrifugal fan generally decrease with a decrease in the … Continue reading

04. January 2011 by admin
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HVAC Ventilation Air Volume

The volume of air required is determined by the size of the space to be ventilated and the number of times per hour that the air in the space is to be changed. Table 3-4 shows the recommended rate of … Continue reading

04. January 2011 by admin
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HVAC Fans and Blowers

Various types of fans are used in air-conditioning applications and are classified as propeller, tube-axial, vane-axial, and centrifugal. The propeller and tube-axial fans consist of a propeller or disk-type wheel mounted inside a ring or plate and driven by a … Continue reading

04. January 2011 by admin
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Resistance Losses in HVAC Duct Systems

In general, it can be said that duct sizes and the depth of a duct in particular are affected by the available space in the building. For this reason, although the round duct is the most economical shape from the … Continue reading

04. January 2011 by admin
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