This section is from the "Modern Machine Shop Construction, Equipment, And Management" book, by Oscar E. Perrigo. Also see Amazon: Modern Machine Shop Construction, Equipment, And Management.
The openings for the discharge of warm air into the building are directed toward the outer walls and downward at an inclination of about 10 degrees. This arrangement is clearly shown in the drawings, Figs. 59 and 60.
The pipes should be well riveted as they are put up, and securely fastened so that they may not be loosened by any jarring or vibration, either of the building or that caused by the pressure of air passing through them.
The fans may be driven by an electric motor or by an engine attached to each fan; or, if preferred, by belts from the main line of shafting. Any of these methods is efficient and has its particular advantages. If an engine is used, the large fan will require it to be of about 27 horse-power and that for the other fan should be of about 20 horse-power.
Live steam being used for heating, the large apparatus will probably require a supply pipe of 6 inches in diameter and the smaller one of 5 inches. The apparatus should be so constructed that a section of it may be separately connected for using the exhaust steam from the fan engine. In the same way the exhaust from the main engines of the works may be utilized and thus save a considerable portion of the live steam required.
In arranging for heating the foundry, different conditions are met with. With the exception of the chipping and pickling room heat is required hardly more than half the time, that is, during the forenoon, and perhaps for an hour or more after the dinner hour, as the heat from the cupolas is considerable.
The general plan of the system is the same as that employed in the machine shop. The apparatus requires but little room on the floor and consists of a fan having a wheel about 78 inches in diameter and 24 inches wide, running at about 400 revolutions per minute, and will require about 6 horse-power to drive it.
An arrangement of pipes can, of course, be made whereby the chipping and pickling room could be warmed independently of the foundry proper, but it would probably not be necessary.
Figs. 61 and 62 show the arrangement of the foundry system of heating, with diameters of the pipes and openings. It will be preferable to run this fan by an electric motor or a small engine, and since these fan blowers for heating purposes are now made with simple and compact engines attached to them, which require very little attention, aside from starting, stopping, and oiling up, they are very convenient in such situations.
It is always important to have the heater as near the space to be warmed as possible.
Fig. 63 gives plans of the first floor and Fig. 64 that of the second floor. Fig. 65 is a longitudinal section through the building. A heating apparatus of the same size and capacity as that used in the foundry is employed. It may be driven by a separate engine, or a motor, or belted from the shaft which drives the machines in the tool room. This latter plan is probably the best, since the power is convenient, and the first cost may be lessened without sacrificing any desirable feature in another direction.
Fig. 61. Cross Section through Foundry, Cupola, Platforms, etc.
Fig. 62. Plan of Heating System for Foundry.
Fig. 63. Plan of Heating System for Office Building. First Floor.
Fig. 64. Plan of Heating System for Office Building. Second Floor.
The system of piping is clearly shown in the illustration and needs little explanation. The main pipe passing through over the driveway must be amply protected, preferably by being encased in a wooden box several inches larger than itself, the space being filled with sawdust or similar material; and this again is covered by another box large enough to leave an air space of about three inches between the two, on all sides.
For the office rooms the pipes may be of rectangular form, concealed by suitable architectural finish of the ceiling, in which lateral openings for registers may be made. Or, proper air ducts may be formed in the side walls and the registers placed at suitable intervals. Or, again, the pipes may be carried around inside the walls, close to the ceilings, and registers located in the same manner.
There may be for this system the double-duct arrangement. That is, two sets of pipes or ducts, one carrying cold and one warm air, the registers being so arranged that they will furnish one or the other, or a mixture of both, by means of what is technically known as a "mixing damper".
Fig. 65. Longitudinal Section through Office Building.
In offices and rooms of moderate size which are heated by warm air being forced into them near the ceiling, it is usual to provide means of escape for the air as it cools and descends to the floor, through grated openings placed two or three feet from the floor, and connected with flues or ducts leading to the roof. But in offices where doors are frequently opened this does not seem to be necessary, the matter of ventilation being of small consequence compared to that of heating.
The forge shop and various other buildings require no special arrangements for heating. The water-closet rooms may be warmed sufficiently by providing grated openings in the wall dividing them from the boiler room. They should be near the ceiling, on each floor.
The question of proper temperature of shops where men are at active work should be considered as quite different from providing for heating a factory where the work is usually much lighter, the number of employees per hundred feet of floor space much greater, and frequently a large proportion of them females.
In a machine shop devoted to a medium class of work, a temperature of about 60 degrees will be found generally comfortable to the majority of the men. We have known of shops where the temperature seldom went above 50 degrees in cold weather, and there was no complaint. The former figure will, however, be more satisfactory.
The temperature in the storeroom, tool room, and pattern shop will need to be about 65 degrees, and in the drawing room and offices, between this and 70 degrees. Unless the ventilation is very carefully attended to, there is more danger in having these latter rooms too warm than not warm enough, and any system of heating which does not recognize the importance of good and thorough ventilation is radically wrong in both theory and practice.