FORMS OF RADIATORS

Radiators are much the same in appearance for both steam and hot-water heating. They are hollow cast-iron columns so designed that they may be fastened together in units of any number of sections. The sections are made in size to present a definite number of square feet of outside surface that is spoken of as radiating surface. The amount of radiating surface in any radiator depends on its height and the contour of the cross-section. The radiator sections may be made in the form of a single column as Fig. 22 or they may be divided into two, three, four or more columns to increase their radiating surface.

The following table, taken from a manufacturer’s catalogue, shows the method of rating the heating capacity of a particular design. In the table, the first column gives the number of sections in the radiator, the second column states the length of the radiator in inches. The columns headed heating surface give the heights of the sections in inches and the amount of radiating surface in various radiators of different heights and numbers of sections. As an example: This table refers to the three-column radiators of Fig. 23. Such a radiator 32 inches high with 10 sections would contain 45 square feet of radiating surface and would be 25 inches in length.

No. of sections	Length 2½ in. per section	Heating surface—square feet
No. of sections	Length 2½ in. per section	45 in. high, 6 sq. ft. per sec.	38 in. high, 5 sq. ft. per sec.	32 in. high, 4½ sq. ft. per sec.	26 in. high, 3¾ sq. ft. per sec.	23 in. high, 3¼ sq. ft. per sec.	20 in. high, 2¾ sq. ft. per sec.
2	5	12	10	9	7½	6½	5½
3	7½	18	15	13½	11¼	9¾	8¼
4	10	24	20	18	15	13	11
5	12½	30	25	22½	18¾	16¼	13¾
6	15	36	30	27	22½	19½	16½
7	17½	42	35	31½	26¼	22¾	19¼
8	20	48	40	36	30	26	22
9	22½	54	45	40½	33¾	29¼	24¾
10	25	60	50	45	37½	32½	27½
11	27½	66	55	49½	41¼	35¾	30¼
12	30	72	60	54	45	39	33
13	32½	78	65	58½	48¾	42¼	35¾
14	35	84	70	63	52½	45½	38½
15	37½	90	75	67½	56¼	48¾	41¼
16	40	96	80	72	60	52	44
17	42½	102	85	76½	63¾	55¼	46¾
18	45	108	90	81	67½	58½	49½
19	47½	114	95	85½	71¼	61¾	52¼
20	50	120	100	90	75	65	55
21	52½	126	105	94½	78¾	68¼	57¾
22	55	132	110	99	82½	71½	60½
23	57½	138	115	103½	86¼	74¾	63¼
24	60	144	120	108	90	78	66
25	62½	150	125	112½	93¾	81¼	68¾
26	65	156	130	117	97½	84½	71½
27	67½	162	135	121½	101¼	87¾	74¼
28	70	168	140	126	105	91	77
29	72½	174	145	130½	108¾	94¼	79¾
30	75	180	150	135	112½	97½	82½
31	77½	186	155	139½	116¼	100¾	85¼
32	80	192	160	140	120	104	88

Fig. 22 is a radiator made up of eight single-column sections. In Fig. 23 is shown five three-column radiators, varying in height from 20 to 45 inches.

The sections of steam radiators are joined together at the bottom with close-nipples, so as to leave an opening from end to end. The sections of hot-water radiators are joined in the same manner, except that there is an opening at both top and bottom. Fig. 30 shows the openings of a hot-water radiator installed as direct-indirect heater. Fig. 24 illustrates a special form of radiator that is intended to be placed under windows and in other places that will not admit the high form. Such a radiator as that shown in the picture is often covered with a window seat and in cold weather becomes the favorite place of the sitting room. Another special form is that of Fig. 25. As a corner radiator this style is much to be preferred to the ordinary method of connection; here the angle is completely filled—there is no open space in the corner.

Fig. 22.

Fig. 23.

Fig. 22.—Single column steam radiator.
Fig. 23.—Three-column radiators of different heights; for steam or hot-water heating.

Wall radiators such as shown in Fig. 26 are made to set close to the wall, where floor space is limited. They are particularly adapted for use in narrow halls, bathrooms and other places where the ordinary type could not be conveniently used.

A radiator that will appeal to all neat housekeepers is that of Fig. 27. It does not stand on the floor as in the case of the ordinary type, but is hung from the wall by concealed brackets. The difficulty of sweeping under this radiator is entirely avoided.

Fig. 28 is a radiator designed to furnish a warming oven for plates and for heating the room at the same time. It is sometimes installed in dining rooms.

Fig. 24.—Six-column, low form of hot-water radiators to be placed under windows.

Fig. 25.—Two-column corner radiator for steam heating.

Fig. 26.—Wall form, radiator for steam or hot water.

The ordinary method of heating by the use of radiators is known as the direct method. The air is heated by coming directly into contact with the radiators and distributed through the room by convection. If the arrangement is such that the air is brought from outdoors and heated by the radiator before entering the room, it is called the indirect method of heating. Such an arrangement is illustrated in Fig. 29. The radiator is located beneath the floor, in a passage that takes the air from outdoors and after being heated, enters the room through a register located in the wall.

Fig. 30 is still another arrangement known as the direct-indirect method of heating. The radiator is placed in position, as for direct heating, but the air supply is taken from outdoors. The radiator base is enclosed and a double damper T regulates the amount of air that comes from the outside. When the inside damper is closed and the outside damper is open, as is shown in the drawing, the air comes from outdoors and is heated as it passes through the radiator on its way to the room. If the dampers are reversed, the air circulates through the radiator as in the case of direct radiation.

Fig. 27.—Two-column radiator suspended from the wall by brackets.

Fig. 28.—Dining-room radiator containing a warming oven.

In the use of the direct or the direct-indirect method of heating the principal object to be attained is that of ventilation, but quite generally the passages are so arranged that the air may be taken from outdoors or, if desired, the air of the house may be sent through the radiators to be reheated. In extremely cold and windy weather it is sometimes difficult to keep the house at the desired temperature when all of the air supply comes from the outside. Under such conditions the outside air is used only occasionally. In mild weather it is common to use the outdoor air most of the time. The cost of heating, when these methods are used, is higher than by direct radiation, because the air is being constantly changed in temperature from that of the outside to 70°.

Fig. 29.—Ventilation by the indirect method of heating.

Fig. 30.—Ventilation by the direct-indirect method of heating.

Radiator Finishings.

—In steam and hot-water heating the decoration of the radiators is a much more important item than that of a good-looking surface or one which will harmonize with the setting. Until recently radiator finishing has been considered a minor detail and the familiar bronze has been looked upon as a standard covering, while painted radiators were considered only a matter of taste. The character of the surface is, however, the determining factor in the quantity of heat given out by radiators. This has been determined in the experimental laboratory of the University of Michigan by Professor John A. Allen. Comparison was made of bare cast-iron radiators with the same forms painted as indicated in the following table. The bare radiator was taken at 100 per cent.; the other finishes are expressed in per cent. above or below that of the bare radiator.

Condensing capacity, per cent.
No. 1, a cast-iron radiator, bare as received from the foundry	100
No. 2, a cast-iron radiator, coated with aluminum bronze	78
No. 3, a cast-iron radiator, three coats of white enamel paint	102
No. 4, a cast-iron radiator, coated with copper bronze	80
No. 5, a cast-iron radiator, three coats of green enamel paint	101
No. 6, a cast-iron radiator, three coats of black enamel paint	101

The author has stated further that, “It might be said in general that all bronzes reduce the heating effect of the radiator about 25 per cent. while lead paints and enamels give off the same amount of heat as bare iron. The number of coats of paint on the radiator makes no difference. The last coat is always the determining factor in heat transmission.”