Fireplaces and Chimneys

by Arthur H. Senner; T. A. H. Miller

If a damper is installed, the width of the opening j, [figure 34], will depend on the width of the damper frame, the size of which is fixed by the width and depth of the fireplace and the slope of the back wall. The width of the throat proper is determined by the opening of the hinged damper cover. The full damper opening should never be less than the flue area. Responsible manufacturers of fireplace equipment give valuable assistance in the selection of a suitable damper for a given fireplace. A well-designed and well-installed damper should be regarded as essential in cold climates.

When no damper is used, the throat opening j should be 4 inches for fireplaces not exceeding 4 feet in height.

Table 3.—Recommended dimensions for finished fireplaces

[Letters at heads of columns refer to [figure 34]]

Opening		Depth, d	Minimum back (horizontal) c	Vertical back wall, a	Inclined back wall, b	Outside dimensions of standard rectangular flue lining	Inside diameter of standard round flue lining
Width, w	Height, h
Inches	Inches	Inches	Inches	Inches	Inches	Inches	Inches
24	24	16-18	14	14	16	8½ by 8½	10
28	24	16-18	14	14	16	8½ by 8½	10
24	28	16-18	14	14	20	8½ by 8½	10
30	28	16-18	16	14	20	8½ by 13	10
36	28	16-18	22	14	20	8½ by 13	12
42	28	16-18	28	14	20	8½ by 18	12
36	32	18-20	20	14	24	8½ by 18	12
42	32	18-20	26	14	24	13 by 11	12
48	32	18-20	32	11	24	13 by 13	15
42	36	18-20	26	11	28	13 by 13	15
48	36	18-20	32	14	28	13 by 18	15
54	36	18-20	38	14	28	13 by 18	15
60	36	18-20	44	14	28	13 by 18	15
42	40	20-22	24	17	29	13 by 13	15
48	40	20-22	30	17	29	13 by 18	15
54	40	20-22	36	17	29	13 by 18	15
60	40	20-22	42	17	29	18 by 18	18
66	40	20-22	48	17	29	18 by 13	18
72	40	22-28	51	17	29	18 by 18	18

Figure 33.—In regions where natural gas is plentiful and in cities, fireplaces of this type, burning gas with a flickering flame, are frequently used as an auxiliary to the main heating plant. Some types have imitation logs of metal perforated for gas jets.