Document oea382Y15gLZEVLrMDbZVaEe3

1/ /.' ; 394 CHAPTER 21 1946 Guide Carrying Capacity The. Btu carrying capacities'of the selected warm air and return air combinations are shown in Tables 6, 7 and 8: Table 6--Combination Numbers 1 to 5--Warm Air Carrying Capacities to first story registers with 1 to 5 elbows and with leaders 4 to 24 ft long. Table 7--Combination Numbers 11 to 16 and 21 to 24--Warm Air Carrying Capaci ties to second story registers with 1 to 5 elbows with leaders 4 to 24 ft long. Table 8--Combination Numbers 31 to 38--Return Air Carrying Capacities for types Ay B, Cy D, E, and F return combinations. Table 4. Return Air Ducts Combi , Duct nation Dia. No. In. Area at Shoe Con nection, Sq In. Metal Grille Sizes Choose One A Bc When Joist Lining , is Used* When Duct is Used No. of Joists - Lined Minimum* Depth. In. Choose One 31 .10 32 12 33 14 34 16 35 18 36 20 37 22 38 24 8x14 10x12 i 6x30 8x24 12x14 1. 170 8x30 10x24 14 x 16 1 220 10x30 12x24 2 280 12x30 14x24 -'2 340 14x30 18x24 2 420 18x30 2 500 20x30 2 7 14 x 6 12 x 8 9 22 x 6 16 x 8 12. 28 x 6 22 x 8 8 28 x 8 .22x10 10 36 x 8 28x10 12.5 36x10 30x12 15.0 42x10 36x12 18.0 42 x 12 36x14 d Based on 14 in. space between joists. Use full depth of joist except when joist depth is less than minimum depth required, xohen pan must be used. 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 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. of 90-Deg Elbows i 1 i 2 2H > Vi ' 3 .3 2 Design Procedure The steps to be taken in designing a gravity warm air duct system are: 1. Calculate the heat loss from each room as explained in. Chapters 6, 8 and 14. . 2. Prepare a layout showing (a) furnace, (6) chimney connection, (c) warm air 'registers (whether floor, baseboard or wall), (d) return air grilles.- 3. .Indicate on each warm air run (using symbols shown in Fig. 4): (a) whether the room to be heated is on the. first or second story, (6) the approximate length of leader pipe in the basement, (c) the number of right angle elbows required-, including the elbow at the boot connection (see Pig. 2), .(d) whether the register is to be located in the floor, in the-baseboard, or in the wall. > _ . . 4r Show the number and proposed -locations of -return air grilles and the type of- return air system (see. Fig. 3). 1 Com bination No.. - Gravity Warm Air Systems. 395 Length o f Leader P ipe-- in Feet_________ T a b le 6. 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OCO^COD OOCOOC5C5 co h t-- -r co Tpco-eoN 04 CO --* CO 04 * cor-ocor- ID r-05 04 CO id t- CO 04 CO id CO C0C4 ID ID CO 00 -- id ^-4 r--t scin 65 H 04 CO O' iD za -H 04 CO t*4 ID w 04-CO ID --t 04 CO ^ iD * if 04 CO iD --I 04 CO ID Additional values for`0 arid 7 elbows are given in original Mjanual. _______________________