Churches may be warmed by furnaces, indirect steam, or by means of a fan. For small buildings the furnace is more commonly used. This apparatus is the simplest of all and is comparatively inexpensive. Heat may be generated quickly, and when the fires are no longer needed they may be allowed to go out without danger of damage to any part of the system from freezing.

It is not usually necessary that the heating apparatus be large enough to warm the entire building at one time to 70 degrees with frequent change of air. If the building is thoroughly warmed before occupancy, either by rotation or by a slow inward movement of outside air, the chapel or Sunday-schoolroom may be shut off until near the close of the service in the auditorium, when a portion of the warm air may be turned into it. When the service ends, the switch damper is opened wide, and all of the air is discharged into the Sunday-school loom. The position of the warm-air registers will depend somewhat upon the construction of the building, but it is well to keep them near the outer walls and the colder parts of the room. Large inlet registers should be placed in the floor near the entrance doors, to stop cold drafts from blowing up the aisles when the doors are opened, and also to be used as foot-warmers.

Ceiling ventilators are generally provided, but should be no larger than is necessary to remove the products of combustion from the gaslights, etc. If too large, much of the warmest and purest air will escape through them. The mam vent flues should be placed in or near the floor and should be connected with a vent shaft leading outbound. This flue should be provided with a small stove or flue heater made especially for this purpose. In cold weather the natural draft will be found sufficient in most cases. The same general rules follow in the case of indirect steam as have been described for furnace heating. The stacks are placed beneath the registers or flues and mixing dampers provided. If there are large windows, flues should be arranged to open in the window sills so that a sheet of warm air may be delivered in front of the windows, to counteract the effects of cold down drafts from the exposed glass. These flues may usually be made 3 or 4 inches in depth, and should extend the entire width of the window. Small rooms, such as vestibules, library, pastor's room, etc., are usually heated with direct radiators. Rooms which are used during the week are often connected with an independent heater so that they may be warmed without running the large boilers, as would otherwise be necessary.



Pierce, Butler & Pierce Mfg. Co.

When a fan is used it is desirable, if possible, to deliver the air to the auditorium through a large number of small openings. This is often done by constructing a shallow box under each pew, running its entire length, and connecting it with the distributing ducts by means of a pipe from below. The air is delivered at a low velocity through a long slot, as shown in Fig. 36.

The warm-air flues in the window sills should be retained but may be made shallower and the air forced in at a high velocity.