374 Molesworth’s pocket-book
Ventilation.
Each person requires at least from 3 to 4 cube
feet of air per minute. Ordinary windows allow
about 8 cube feet a minute to pass.
Warming by Steam.
When the external temperature is 10° below-
freezing point, in order to maintain a temperature
of 60°.
One superficial foot of steam-pipe for each
6 superficial feet of glass in the windows.
One superficial foot of ditto for every 6 cube of
air escaping for ventilation per minute. .
One superficial foot of ditto for every 120 feet
of wall, roof, or ceiling.
One cube foot of boiler is required for every
2000 cube feet of space to be heated. ~
One horse-power boiler is sufficient for 50,000
cube feet of space.—Steam should be about 112°.
Warming by Hot Water.
P — Temperature of pipes. .
T = Temperature required in building.
t = Temperature of external air. .
C = Cube feet of air to be warmed per minute.
L = Length of pipe in feet.
T, = X ‘0045 C. for 4-in. pipes.
„ 3-in. .
l =x ■°09 » 2'in- ”