Science for beginners . the impure air to escape? Find whereand how the impure air is permitted to escape from your school-room. Write a short description of the way your schoolroom isheated and ventilated. 276. Heating and Ventilating the Several-room SchoolBuilding.—Forced systems of ventilation are generally usedin modern school buildings containing several rooms. As wasthe case in the one-roomed school, so here we find that theheating and ventilating systems are usually combined. When SYSTEMS OF VENTILATION 253 such large quantities of air must be moved the gravity systemis not adequate, t
Science for beginners . the impure air to escape? Find whereand how the impure air is permitted to escape from your school-room. Write a short description of the way your schoolroom isheated and ventilated. 276. Heating and Ventilating the Several-room SchoolBuilding.—Forced systems of ventilation are generally usedin modern school buildings containing several rooms. As wasthe case in the one-roomed school, so here we find that theheating and ventilating systems are usually combined. When SYSTEMS OF VENTILATION 253 such large quantities of air must be moved the gravity systemis not adequate, the forced system must be employed. More-over, school buildings containing several rooms are likely tobe heated by steam and steam power is therefore available fordriving the fan, or blower, if desired. Forced systems of heating and ventilation may be of thepropulsion type, known as the plenum system, or it may bethe suction system, or a combination of the two systems. 277. The Plenum System.—In the plenum system the. Fig. 185.—Showing the plenum system for warming and ventilatinga school building. A tempering stack is shown at the right, next (tothe left) is an air washer to insure pure and reasonably moist air,next is a fan or blower, and following that a re-heater, which warmsthe air to any desired temperature. blower or fan is usually placed in the basement and forces allthe fresh, heated air needed for heating and ventilationthrough air ducts into the various rooms. The air in all therooms is, therefore, somewhat compressed, that is, the air inall the rooms is under somewhat greater pressure than is theair outside the building. Hence the name plenum meaningfull. Figure 185 shows the usual construction of the plenum typeof heating and ventilating systems. The fresh air enters atthe window A. It then passes through a bank of steam 254 VENTILATION pipes called the tempering coils, or tempering stack, the temperature of the air is raised to about 65 °F. Itthen pas
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