Many of the hot-water radiators, as shown in Fig. 101, are made with an opening at the top for the entrance of water and at the bottom for its discharge, thus insuring a supply of hot water at the top and of colder water at the bottom.

FEED

CONNECTION

CONNECTION

ELEVATION

WALL LINE

FLOGA LINE

Some of the hot-water radiators are constructed with a cross-partition so that all water entering passes at once to the top, from which it may take any passage

00000000 toward the outlet.

FLAN

TOM CONNECTIONS

The hot-water radiator, is however,

FIG. 103.*-RADIATORS usually made with continuous passages WITH TOP AND BOT- at top and bottom, and the warm water is supplied at one side and drawn off on the other, as shown in Figs. 102 and 105 (right hand). The action of gravity is depended on for making the hot and lighter water pass to the top and the cold water to sink to the bottom and flow off in the return.

Hot-water radiators are also made by joining vertical pipe sections with nipples at top and bottom, as shown in Fig. 106.

*Heating and Ventilating of Residences, by Willet.

68. Direct-indirect Radiators.-Radiators arranged with a damper under the base and located so that air from the out

side will pass over the heating surface before entering the room are often used to improve the ventilation. The surface of these radiators should be about 25 per cent greater than that of a direct radiator for heating the same space. The styles and kinds either for steam or hot water are the same as the direct.

69. Indirect Heaters.-Radiators which are employed to heat the air of a room in a passage or flue which supplies air are termed indirect. These heaters are made in various forms, either of pipe arranged in return bend or in manifold coils, as in Fig. 93, or of cast-iron sections of various forms united in different ways. When cast-iron surfaces are used, they are generally covered with projections like the extended surface radiator. The sections, or, as they are sometimes called, the stacks for indirect heating, are usually held together by bolts. The joints being formed by inserting packing between faced surfaces. The sections are sometimes united by nipples screwed into branch-tees above and below, as shown in Fig. 109, which is an excellent form for hot-water circulation.

Indirect radiators should be placed in a chamber or box as

nearly as possible at the foot of a vertical flue leading to the room to be heated.

Air is admitted through a passage from the outside provided with suitable dampers to a point beneath the indirect stacks. It is taken off generally on the opposite side, and directly into the flue leading into the room. to be heated.

The chamber surround

ator is usually built of

FIG. III.-ARRANGEMENT OF INDIRECT

HEATER.

a casing of matched wood, as in Fig. 111 and Fig. 112, sus

pended from the ceiling of the basement, and lined inside with.

bright tin; but a small chamber of masonry at the bottom of a flue is a better and more durable construction. The flue leading from the chamber is of masonry or galvanized iron; that supplying the cold air, of matched wood. and sheet iron. There should be a door in the chamber so that the indirect heater can be examined and cleaned when required. It is often of advantage to have a passage and deflecting damper so arranged that air can be drawn into the

room for ventilation without passing over the heater.

The registers for admitting the heated air into the rooms can be located as desired, either in the walls or the floor; for ventilation purposes it is preferable to admit the air near the ceiling, and as shown in Fig. 113.

The size of registers and airflue will be given in Chapter XIII.

Setting of Indirect Heaters.The indirect heating-surface is supported usually by bars of iron or pieces of pipe held in place by hangers fastened at the ceiling (Fig. 1). This heater should be set so as to give room for the freest possible circulation of air, and so that all parts will be at least ten inches from top or bottom of casing, and arranged so