VENTILATION.

The quantity of air for each minute for one person is from four to fifteen feet—and from one-half to one foot should be allowed for each gas jet or lamp.

Heated air cannot be made to enter a room unless means are provided for permitting an equal quantity to escape, and the best places for such exit openings is near the floor.

For healthful ventilation the indirect system of steam heating is by far the best yet devised, for it not only warms the room, but insures perfect ventilation as well. In this system, the air for warming the room is introduced through registers, having first been heated by passing over coils of pipe or radiators suitably located in the air ducts. There is a large volume of pure air constantly entering the room, which must displace and drive out an equal quantity of impure air. This escapes principally around the doors and windows, so that not only is the ventilation effected automatically without the use of special devices, but all disagreeable indraft of cold air is prevented.

One of the cheapest and best methods of ventilation is to have an opening near the floor, opening directly into the flue, or some other outlet especially constructed for it, with hot water or steam pipes in this opening. A moderate degree of heat in these pipes will create a draft, and draw out the bad air. Only a few of these pipes are necessary, and the amount of hot water or steam required to heat them is too small to be worthy of consideration.

The use of a small gas-jet, burning continuously, in a pipe or shaft has been found to be a most admirable method of ventilating inside rooms, closets and similar places where foul air might collect if not replaced by fresh. The following table exhibits the result of careful experiments made by Mr. Thomas Fletcher, of England, with a vertical flue 6 inches in diameter and 12 feet high:

Table.

Gas Burnt
per Hour.		Speed of
Current per
Minute.		Total Air
Exhausted
per Hour.		Air Exhausted
per Cubic foot
of Gas Burnt.		Temperature at
outlet. Normal
62° Fahr.
Cubic Feet.Feet.Cubic Feet.Cubic Feet.
12052,4602,460 82°
22452,9401,470 92°
43253,900 975110°
84154,980 622137°

EXHAUST STEAM HEATING.
Fig. 144.

Taking the experiments as a whole, it will be seen that in a flue 6 inches in diameter, the maximum speed of current which can be obtained with economy is about 200 feet per minute; and this was realized with a gas consumption of 1 cubic foot per hour—1 cubic foot of gas removing 2,460 cubic feet of air.

It should, however, not be required of any system of heating to more than aid in ventilation. It is the architect’s or builder’s performance to so arrange lower and upper openings to drive out the bad air.