Document EdbpvmVeDdb6KpVyzN55JL9YL

400 CHAPTER 21 '1948' Guide all correlated. Similarly in the case of return ducts, the selection specifies a'complete unit consisting of return grille, return duct, and shoe connection1 Recommended Standard Sizes . For the purpose of simplification and standardization, selected com binations of commercial sizes of warm air pipes, return air pipes, ducts, grilles, fittings, and .registers are designated as Combination Numbers. The numbers assigned and the; combinations selected as standard are listed in the following tables *. . .Table !--Combination Numbers 1 to 5--First Story, Warm Air Ducts and Registers. Table 2--Combination Numbers 11. to 16--Second Story Warm Air Ducts, Single Wall Stacks, Fittings, and Registers. Table 3--Combination Numbers 21 to 24--Second Story Warm Air Ducts, Double Wall Stacks, Fittings, and Registers. Table 4--Combination Numbers 31 to 38---Return Air Ducts, Fittings, and Grilles. Table 1. First Story Warm-Air Ducts* Combination , . No. . Leader Pips Diameter. In. 18 29 3 . 10 4 ' ,12 5 14 Floor . 8x 10 9x12 10 x 12 12x14 14 x 16 Register Size, In. Baseboard Size Extension 10 x 8 12 x 8 12 x 9 13 x 11 2H 2K 3X 5M . .. .When .the calculations indicate a requirement for a given room greater than Combination No. 4, two or more smaller units totalling the required capacity are recommended. Table 2. Second^ Story Warm-Air Ducts--Single-Wall Stacks and Fittings Combi- . NATION f No., Leader' Pipe Diameter. In. Stack b Size In. ' Floor Register Size, In. ' Baseboard Size Extension . . Sidewall ...ii 12 14 15 16 8 .. 9 10 12 12 10 x 3M 12 x 3M 14x3K 12 x 5M14x5M 8 x .10 9x 12 10 x 12' ..... . . 10 x 8 12 x 8 12 x 8 12 x 9 13 x 11 . 2X 2M ' 2M 3H 5M . 10x8 12 x 8 12 x 8 . ^Recommended stack sizes. Tables may also be applied to 3 in. and in; stack depths. . Table. 3. Second Story Warm-Air Ducts--Double Wall Stacks and Fittings Combi nation No. Leader Pips Diameter, In. Stack Size. In. : Internal External Floor - 21 22 23 24 8 8 ,9 9 2HC x 10 3 . x 10 2J^C x 12 3 x 12 3Hcxl05^ 3% xioyB 3^x12^ 3% xl2% 8x 10 8x 10 9x 12 9x 12 Register Size, In. . . Baseboard Size Extension Sidewall 10 x 8 10x8 12x8 12x8 2M 10x8 2K 10x8 2M 12x8 2K 12 x 8 .cCommerdal sizes vary )4 in. from values shown. Gravity Warm Air Systems______ ; .r/r\*\ 401 Table 4. Return Air Ducts 1 Combi nation No. 31 32 33 34 35 36 37 38 Duct Dia. In. 10 12 14 16 18 20 22 24 Area at Shoe Con nection, Sq In. Metal Grille Sizes Choose One .A B c When Joist Lining is Used* When Duct is . Used No. of Minimum* Joists Depth;. Lined In. Choose One 170 220 280 340 420 500 6x30 8x30 10x30 12x30 14x30 18x30 20x30 8x14 8x24 10x24 12x24 14x24 18x24 10 x 12 12x14 14x16 i i i 2 2 2 2 '2 '7 : 9. 12 8 10 12.5 15.0 18.0 14 x 6 22 x 6 28 x 6 28x 8 36 x 8 36x10 42x10 42x12 12 x 8 16 x 8 22 x 8 22x10 28x10 30x12 36x12 36x14 dBased on 14 in. space between Joists. *Use full depth of joist except when joist depth is.less than minimum depth required, when Pan must be used. The selected types of boots are shown in Fig. 2 and their resistances expressed in equivalent elbows are shown in Table 5. It is essential that Fig. 2. Typical Warm Air Boots Table 5. Resistances of Warm Air Boot Combinations Expressed in Elbow Equivalents Warm Air Boot A B C D E ' F. G H I Name of Combination 45-Deg Ajigle Boot and 45-Deg Elbow 90-Deg Angle Boot Universal Boot and 90-Deg Elbow End Boot Offset Boot 45-Deg Angle - 1 Floor Register^--Second Story Offset Offset ` Equivalent No. of 90-Deg Elbows i i i 2 2 Vi - -H .3 3 .... 2