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Ceiling fans aid in the distribution of fresh air in both mechanically ventilated and naturally ventilated spaces. In naturally ventilated spaces, ceiling fans are effective at drawing in and circulating fresh outdoor air. [7] In mechanically ventilated spaces, fans can be focused to channel and circulate conditioned air in a room.
In ventilation systems, a jet fan, also known as an impulse or induction fan, ejects a stream of air that entrains ambient air to circulate the ambient air. The system takes up less space than conventional ventilation ducting and can significantly increase the rates of inflow of fresh air and expulsion of stale air. [26]
Diagramatic operation of a thermal wheel Ljungström Air Preheater by Swedish engineer Fredrik Ljungström (1875–1964). A thermal wheel, also known as a rotary heat exchanger, or rotary air-to-air enthalpy wheel, energy recovery wheel, or heat recovery wheel, is a type of energy recovery heat exchanger positioned within the supply and exhaust air streams of air-handling units or rooftop ...
A centrifugal fan is a mechanical device for moving air or other gases in a direction at an angle to the incoming fluid. Centrifugal fans often contain a ducted housing to direct outgoing air in a specific direction or across a heat sink; such a fan is also called a blower, blower fan, or squirrel-cage fan (because it looks like a hamster wheel).
Typical modern mechanical ventilation systems use as little as 2000 J/m 3 for fan operation, and in cold weather they can recover much more energy than this in the form of heat transferred from waste exhaust air to fresh supply air using recuperators. Ventilation heat loss can be calculated as: = (). Where: is ventilation heat loss in W; is ...
As more architecture incorporated mechanical ventilation, the cost of outdoor air ventilation came under some scrutiny. In 1973, in response to the 1973 oil crisis and conservation concerns, ASHRAE Standards 62-73 and 62–81) reduced required ventilation from 10 CFM (4.76 L/s) per person to 5 CFM (2.37 L/s) per person. In cold, warm, humid, or ...
A fan may be installed in an attic for the different purpose of cooling a whole house, venting hot air out via the attic; such fans are often called whole-house fans. Wind-powered roof turbine ventilator. Mechanical attic ventilation fans may be powered in a variety of different ways. Most attic ventilators fitted to homes are powered off mains ...
The axial fan is often contained within a short section of cylindrical ductwork, to which inlet and outlet ducting can be connected. Axial fan types have fan wheels with diameters that usually range from less than a foot (0.3 meters) to over 30 feet (9.1 m), although axial cooling tower fan wheels may exceed 82 feet (25 m) in diameter.