Purdue University Agricultural Extension Service Department of Poultry Husbandry
November, 1949 May,1951 (3c)
USE OF SPACE UNIT HEATERS FOR BROODING By Alexander Gordeuk
Recently three articles about the use of unit space heaters have appeared in national magazines (See page 2). Since then inquiries about this latest idea in brooding equipment have come from many states.
The use of unit or space heaters (hot water, steam or gas) for brooding isn't expected to create a revolution nor provide all the answers to large scale brooding. As a matter of fact the method is merely a variation of one that has been in use for a long time, namely, warm room brooding. Unit heaters heat the entire volume of air in the room. Chicks may be started either all over the floor as with "radiant heating" or in small areas encircled with guards. The best starting temperature seems to be 88° to 92°F, two inches above the litter. The exact temperature can best be determined by observing the reaction and comfort of the chicks. It may be possible to start chicks at a still lower temperature and get very satisfactory results, but careful trials are needed before recommending less than 88°F. 
Most of the inquiries thus far seem to concern the use of gas unit heaters,
Mr Noel Shaver, Crawfordsville, Indiana was the first to use such equipment; although steam space heaters were first used for brooding by Leon Johnson of Orleans, Indiana, Mr. Shaver found gas unit heaters comparatively cheap to install. They perform satisfactorily and the cost to install gas unit heaters in a broiler house 50' x 140* with a capacity of 10,000 chicks was about $1400. This included the gas tank, heaters, and the complete cost of installation.
This is considerably less than the cost of any other central heating installation and not much above the cost of individual hovers for the same brooding capacity.		
The cost of brooding per chick cannot be given accurately. As with any other system there are many variables. One group of 10,000 broiler chicks raise  in early fall with gas unit heaters was brooded for considerably less than 1¢ per bird. The cost of the propane gas used was 14¢ per gallon.
Many inquiries concern the capacity of the unit heaters that should be installed. The proper answer to this query is to provide enough BTU output capacity to heat the house. It is obvious that there is no one set answer and that it is best to get a heating engineer to figure out the necessary size of the units as so much depends on insulation, ventilation, and the location in the building. To arrive at an estimation, the engineer must consider such factors as the size of the house, the volume of air in the house to be heated, the type of construction, air leakage through doors, windows and other openings, the insulation value of the walls and the roof or ceiling, the ventilation system, the highest inside temperature desired, and the lowest expected outside temperature during winter brooding. Obviously, this is not a job for a layman to do on a hit-or-miss basis.
From field observations to date two main objections can be found to the system of brooding using unit space heaters. First, the entire house must be kept at a rather high temperature so that caretakers may complain about working conditions. Second, it is essential to have access to a stand—by electric power unit in case there is a power failure in the community or provide some other method of stirring the air if there is a power failure.