HVAC Control in the New Millennium.pdf - HVAC.Amickracing

Heat, Ventilation and Damper Control TrendsProperties of AirAir is a mixture of two main gases, approximately 23 parts ofoxygen and 77 parts nitrogen by weight. The other gases in air includescarbon dioxide, carbon monoxide, ozone and neon in small quantities.Carbon monoxide is not generally present in the atmosphere, butis found in congested motor traffic. It is dangerous and is also given offby stoves and furnaces. Air containing carbon monoxide in a concentrationgreater than 0.10% is fatal to humans.Oxygen is the most important constituent of air, it makes up about1/4 of the air by weight and 1/5 of the air by volume and provides theexistence of all animal life. Nitrogen is an inert gas which acts to diluteoxygen.Air CirculationAir circulation is important for two reasons. Air that is moving cancarry away the moisture and heat surrounding the body. If this is notdone, the occupants can be uncomfortable even when the relative humidityof the area is low.Air that is drawn into the conditioner and passed out over theevaporator will remove the moisture from the room which is condensedand passed through the drain.Although the movement of air is essential, direct drafts should beavoided. Condensation on the evaporator surface during summer operationproduces a certain amount of cleaning since the moisture absorbsimpurities from the air as it passes over the evaporator surfaces. Thecondensation of the moisture continues to carry off these impurities tothe drain.FiltersAir cleaning and filtering devices can eliminate most particles carriedin the air that are detrimental to health and comfort. These includedust, fumes, and smoke. Dust and fumes tend to settle in still air, butsmoke is actuated by motion and if not removed, will remain in motionin the air.©2001 by The Fairmont Press, Inc. All rights reserved.