366 ARTIFICIAL BROODING 
understand the fixtures, the size of the pipes, and the running of 
the boiler to secure the required degree of heat in a given type of 
building. The construction of the building and the amount of 
glass or muslin in front will influence the amount of heat re- 
quired. In a brooder house one hundred feet long the best plan 
is to run two coils of two-inch pipe one on the back wall and one 
on the front, each coil containing two flow pipes and one return, in 
addition to the hover heat. In most conditions this should maintain 
a steady temperature of from 60° to 75° in all kinds of weather. 
In a brooder house in which the hovers are heated from a central 
heating plant, so much wall pipe may not be necessary, since con- 
siderable heat will be given off by the hover pipes themselves. 
Before starting up the fire at the beginning of the brooding 
season, one should make sure that the system is full of water; 
if so, there will be water in the bottom of the glass in the expansion 
tank. If the air valves are not automatic, all of them should be 
left open when water is flowing into the tank, so that the air 
may escape from the pipes and permit them to fill with water. 
Neglect of this precaution, and starting the fire with too little 
water in the system, may burst the boiler. 
A good practice is to start the fire and get it well under way 
before putting any coal on it. The use of coal is recommended, 
since it burns longer, gives a more uniform heat, and does not 
require much attention. To make the fire burn briskly, the pipe 
damper should be open and the upper door closed. When the 
fire is well started and there is a good bed of coals, and the water 
has reached the desired temperature, check the fire by closing 
the pipe damper and the damper in the ash-pit door, and leave 
the upper door ajar—how much ajar can only be learned by 
practice. This depends on the type of boiler, the varying amounts’ 
of water in the system, and will also be influenced by weather, 
wind, and rain. Never let the water in a hot-water system reach 
a temperature of 212°, for steam will then be formed, the water 
in the system will be greatly reduced, and there is danger of its 
boiling away and leaving the boiler dry. When it approaches 
this degree of temperature, the water should immediately be cooled 
by banking the fire and cutting off all drafts. If steam should 
form in the coils, some of it must be allowed to escape by opening 
the air valves, then let fresh water into the system gradually. 
It is best to have automatic valves. All ashes should be removed 
from the ash pit daily, for if they are allowed to remain they will 
