The heating of a building is generally made the subject of a special contract.

The three usual methods for house heating are, the Hot Air Furnace, the Hot Water Boiler, or the Steam Boiler. Sometimes a combination system of hot air and steam, or hot air and hot water is used.

Estimates of the cost of heating should be obtained from contractors who follow this particular branch of construction.

In general, for an ordinary class of building such as residences, apartments, stores, etc., the heating will range according to the system used, from 6% to 12% of the cost of the building, as follows:

 Hot air furnace 6 to 7 per cent. Steam 8 to 10 per cent. Hot water 10 to 12 per cent.

These figures are approximate and the only reliable way to obtain the actual cost is by taking off the items and figuring each job by itself.

Quantities. The hot air heating of an ordinary house can be approximated closely by the builder on the basis of cubic contents to be heated; and the area of piping and capacity of the furnace can be approximated by means of the following general rules:

To determine the size of pipe for any room, find the cubic contents of the room in cubic feet and divide this by 25 for rooms on the first floor, and by 35 for rooms on the second and third floors.

Make the cold air box at least 3/4 of the combined area of pipes, none of which should be smaller than 7 inches in diameter.

Example. For a small house of seven rooms the quantities may be as follows:

## First Floor

Parlor 12 x 15 x 9 ft. high 1624 cu. ft. divided by 25 == 65 sq. in. or 9 in. pipe Hall 8 x 20 x 9 ft. high 1440 cu. ft. divided by 25 = 58 sq. in. or 9 in. pipe Add 40% for second story hall space making 81 sq. in. = 10 in. pipe Dining Room 14 x 15 x 9 ft. high 1890 cu. ft. divided by 25 = 76 sq. in. or 10 in. pipe

 SECOND FLOOR Chamber 13x15x81/2 = 1658 cu. ft. ÷ 35 = 48 sq. in. or 8 in. pipe Chamber 11x12x8 1/2 = 1122 cu. ft. ÷ 35 = 32 sq. in. or 7 in. pipe Chamber 14 x 16 x 8 1/2 = 1904 cu. ft. ÷ 35 = 55 sq. in. or 8 in. pipe Bath Room 8 x 10 x 8 1/2 = 680 cu. ft. ÷ 35 = 20 sq. in. or 7 in. pipe
 Total pipe area: 2-10 in. pipes 78 sq. in. each 156 sq. in. 1 - 9 in. pipe 64 sq. in. 64 sq. in. 2 - 8 in. pipes 50 sq. in. 100 sq. in. 2 - 7 in. pipes 38 sq. in. 76 sq. in. Total pipe area 396

From this scale we can determine the size of the furnace and the cost of piping.

A furnace to carry say 400 to 500 sq. feet of pipe area would cost, set in place, from \$100 to \$125. The labor on pipes, registers, and furnace \$20 to \$24.

The cost of piping will depend on the distances to run but the material can be estimated as follows:

Round tin pipes will cost; from A. A. charcoal plates,as follows:

 Size of Pipe 6" 7" 8" 9" 10" 1l" 12" 13" 14" 15" 16" 18" Per Foot... .09 .10 .12 .14 .16 .18 .23 .25 .27 .28 .30 .32 Hot Air Damper.. .12 .12 .12 .15 .15 .15 .18 .18 .18 .20 .20 .25 Furnace Collars... .10 .10 .10 .12 .12 .14 .18 .18 .18 .20 .20 .25 Tin Elbows... .12 .15 .18 .20 .25 .30 .35 .40 .45 .50 .60 .70

* REGISTERS

 Size 6x10 7x10 8x10 8x12 9x12 10x14 12x15 12x16 14x18 16x20 Black Register .50 .52 .52 .58 .64 1.08 1.37 1.70 2.74 3 75 Slate Stone.. .38 .42 .44 .50 .63 .70 .93 1.00 1.50 2.35 Register Box.. .14 .16 .17 .20 .23 .27 .33 .35 .38 .50 Netting... .05 .05 .06 .06 .07 .07 .08 .08 .10 .12 Totals... 1.07 1.15 1.19 1.34 1.57 2.12 2.71 3.13 4.72 6.72

* July, 1906. - Add one-third.

Galvanized smoke pipe will cost 9c per lb. and will weigh per lineal foot as follows:

 Size No. 4" 5" 6" 7" 8" 9" 10" l1" 12" 13" 14" 22 1 3/4 2 1/8 2 5/8 3 3 3/8 3 1/4 4 1/8 4 1/2 5 5 1/4 5 3/4 24 1 1/4 1 5/8 1 7/8 2 1/8 2 1/2 2 3/4 3 3 3/8 3 5/8 3 7/8 4 1/4