. American school building standards . itiatedair, or both; but where no method was employed forforcing fresh air in through the former, or drawingthe foul air out through the latter, such systems offlues were even less dependable than the natural pro-cesses above referred to. This led to a further stepin advance known as the Gravity System and con-sisting of some means of encouraging or inducing amovement of the air in the rooms into the foul airflues. One such plan involves the use of two fluesfor each room, one leading into the room from a fur-nace, or battery of furnaces, located in the ba
. American school building standards . itiatedair, or both; but where no method was employed forforcing fresh air in through the former, or drawingthe foul air out through the latter, such systems offlues were even less dependable than the natural pro-cesses above referred to. This led to a further stepin advance known as the Gravity System and con-sisting of some means of encouraging or inducing amovement of the air in the rooms into the foul airflues. One such plan involves the use of two fluesfor each room, one leading into the room from a fur-nace, or battery of furnaces, located in the basement,and the other leading from the room to a point abovethe roof of the building. It is the theory of thissystem that when the air used for heating the roomsleaves the furnaces, it both rises and expands in 102 volume, because of its heat and lighter specificgravity, and thus enters the room with a certainvelocity due to these causes. This velocity is sup-posed to be sufficient to displace an equal volume of Went Stack Smoke Grayjty SystemOf Mot Air Indirect HeatingAmd Ventilating Combined. This illustration shows diagramatically the principleof a gravity system of heating and ventilation, showing thepath of outside cold air as it passes over the furnace, upinto the school room and outdoors again through the ventstack. The motion of the air is produced by the heat ofthe furnace. the air already in the room and force it up the ventflue and thus out doors. This is a beautiful theoryand such systems sometimes do operate with a fairdegree of satisfaction when the wind and weather 103 conditions are favorable, but if the winds or weatherare unfavorable, the system is just as certain toprove ineffectual and little better than no system ofventilation whatever. A final step in the development of the gravitysystem consists in placing gas jets, steam coils, ironsmoke stacks, etc., in the exhaust flues, with the ideathat the heat thus generated will cause a positivedraught and
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectschoolb, bookyear1910
