Document DMp7me0Rz1MqVONYQGezd7L7n

436- CHAPTER 21 1949 Guide OUTLINE OF DESIGN PROCEDURE The data underlying the design prpcedure are given in detail in a circular2 issued by the University of Illinois. . In, this procedure the design of the warm-air duct system is considered as an entire unit, so that for a given, heat loss the, sizes of leaders, stacks, boots, stackheads, and registers are all correlated. Similarly in the case of return ducts, the selection specifies a complete unit consisting of return grille, return duct, and shoe connection. Recommended Standard Sizes For the purpose of simplification and standardization, selected combina tions 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 1, to 4 inclusive*. , ., Combination No. .' i 2 3 .. 4 5 Table 1. First Stoby Warm-Air Ducts* Leader Pipe Diameter. In. Floor . Register Size. In. Baseboard Size ' Extension -8 9 10 12 14 8x 10 9x 12 10x12 12 x 14 14 x 16 10 x 8 12 x 8 12 x 9 13 x 11 VA 2A 3A - 5A * 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 No. : Leader Pipe- Dlameter. - In. - Stack b Size In. u 8 10 X 3A 12 9 . 12 x 3A 14 10 14'x 3A 15 12 . 12 x 5A 16 .12 . 34 x 5A Floor 8x 10 9 x 12 10x12 ... . . Register Size, In. Baseboard Size Extension 10 x 8 12 x 8 ' 12 x 8 12 x 9 13 x 11 2A . 2A.. . 2A 3A .5A. Sidewall 10x8 V 12 x 8 .12x8 ... b Reoommended stack sizes. Tables may also be applied to 3 in. and 3Yt in. stack depths. Table 3.. Second Story Warm-Air Ducts--Double. Wall Stacks and Fittings Combi nation No. Leader Pipe Diameter. In. Stack Size. In. Internal External Floor Register Size. In. . Baseboard Size Extension SidewaLl4'' . 21 22 23 24. 8 8 9 9. 2Acx 10 3Hcx 10% 3 x 10 3A xl0% 2AC x 12- 3Acxl2H 3 x 12- 3V xl2% 8x 10 8x 10 . 9 x 12 9x 12 10x8 10x8 12x8 12x8 2A io it 8 : 2A . 10 X 8 : -2A -- 12x8 . 2a:. . 12x8 * Commercial sizes vary l/ in. from values shown. , Gravity Warm Air Systems 437 ' - Table 4. Return Ala Ducts 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 USEX>4 When Duct is Used No. of Minimum* Joists Depth, - Lined In. Choose One 8x14 10x12 6x30 8x24 12x14 170 8x30 10x24 14x16 220 - 10x30 12x24 280 12x30 14x24 340 14x30 18x24 420 18x30 e 500 20x30 i i i 2 2 2 2 2 7 14 x 6 12 x 8 9 22 x 6 16 x 8 12 28 x 6 22 x 8 8 28x 8 22x10 10 36 x 8 28x10 12.5 36x10 30x12 15.0 42x10 36x12 18.0 42x12 36x 14 d Based on 14 in. apace between joists. * Use full depth of joist except when joist depth is less than minimnm depth required, when pan must be useAM - FG HI Fia. 2. Typical Warm Air Boots Table 5. Resistances op Wabm Air Boot Combinations ... Expressed in Elbow Equivalents Warm Air Boot A B C D E F G -H I - - - Name of Combination 45-Deg Angle Boot and 45-Deg Elbow 90-Deg Angle Boot Universal Boot and 90-Deg Elbow End Boot Offset Boot 45-Deg Angle ' Floor Register--Second Story Offset Offset . Equivalent No. op . 90-Dec Elbows 'i i i 2. 2A A 3 . .. . 3, 2"