Document XzgzOz5b7j3Q5ewMmYQ6Xd5b4

470 CHAPTER 19 1956 Guide Table 7. Warm Air Capacity, Btuh Delivered Second Story Registers Actual Length (Bonnet to Boot) Feet ; e 4 . 6 . 8 - 10 1 12 14 16 18 WON No. ; Elbows 6H 4 6 8 10 12 14! . 16 : 18 " 20 7. 4 6 8 10 12 14 16 18 20 22 m . 4 6 8 10 12 14 16 18 20 22 . 24 11 or 22 VI or 24 14 . 15 11 or 22 12 or 24 14 15. 11 or 22 12 or 24 14 15 11 or 22 12 or 24 14 15 11 or 22 12 or 24 14 . 15 ;s ; O ,: 8,370 8,140 7,900 7,670 7,430 7,190 6,950 6,710 6.470 6,240 6,000 10,040 9,760 9,470 9,190 8,900 8,620 8,330 8,050 7,770 7,480 7,200 11,710 11,380 11,050 10,720 10,390 10,060 9,720 9,390 9.060 8,730, 8,400 16,200 15,750 15,300 14,840 14,380 13,920 13,460 13,000 12,550 12,100 11,640 o . x> 7,940 7,720 7,500 7,280 7,050 6.830 6,600 6,370 6.150 5,930 5,700 ; 9,540 9,270 9,000 8,730 8,460 8,190 7,920 7,650 7,380 7,110 6,840 11,120 10,810 10,500 10,180 9,870 9,550 9,230 8,920 8.61Q 8,290 7,980 |1" 15,400 14,970 14,530 14,100 13,670 13,230 12,800 12,360 11,930 11,500 11,070 ' ^ 7,530 7,320 7,110 6,900 6,680 6,470 6,250 6,040 5,830 5,620 5,400 9,030 8,780 8,520 8,270 8,010 7,750 7,500 7,240 6,990 6,730 6,470 i1f3 . a 10,530 10,240 9,940 9,650 9,350 9,050 8,750 8,450 8,160 7,860 7,560 14,580 14,180 13,780 13,370 12,950 12,530 12,120 11,710 11,300 10,890 10,480 fi-K ' 7,120 6,920 6,720 6,520 6,310 6,110 5,900 5,700 5,500 5,300 5,100 o 8,530 8,290 8,050 7,810 7,570 7,330 7,080 6,840 6,600 6,360 6,120 4 . 9,950 9,670 9,390 9,110 8,830 8,550 8,260 7,980 7,700 7,420 7,140 13,780 13,390 13,000 12,610 12,220 11,830 11,440 11,050 10,670 10,280 9,890 6,700 6,510 6,320 6,130 5,940 5,750 5,560 5,370 5,180 4,990 4,800 8,040 7,810 7,580 7,350 7,130 6,900 6,670 6,440 6,220 5,990 5,760 5 9,370 9,110 8,850 8,580 8,310 8,050 7,780 7,510 7,250 6,980 6,720 12,970 12,600 12,240 11,870 11,500 11,140 10,770 10,400 10,040 9,680 9,310 Notes: When floor registers are used on second story rooms, include the equivalent elbow resistance for the cross-over connection as shown in Fie. 2. Combination Numbers 21 and 23 as shown in Tables 2. and 3 are composed of narrow stacks for narrow stud spaces. For Combination No. 21, the capacities are the Btuh deliveries shown for Combination Nos. 11 or 22 multiplied by 0.83. For Combination No. 23, the capacities are the Btuh deliveries shown for Combination Nos. 12 or 24 multiplied by 0.83. Table 8. Return Air--Carrying Capacity--Btuh Serviced Return Ant CombinaWON No. 31 32 33 34 35 36 37 38 Duct Diam. In. 10 12 14 16 18 20 22 24 Type A BTUH 11,300 16,300 22.200 29,000 36.700 45,300 54.800 65,200 Types B and C BTUH 9,500 13,700 18,700 24,400 30,800 38,000 46,000 54,800 Type D BTUH 7,800 11,300 15,300 20,000 25,300 31,300 37,800 45,000 Type E BTUH 7,800 11,300 15,300 20,000 25,300 31,300 37,800 45,000 Type F BTUH 5,000 7,200 9,800 12.800 16,200 20,000 24,100 28,700 Return Air ComBINATION No. 31 32 33 34 35 36 37 38 4. Show the number and proposed locations of return air grilles and the type of Tetum-air system (see Fig. 5). 5. From Table 6, for first story, or from Table 7 for second story, select the com bination number for the warm air system which will supply the heat required to each room, with the number of elbows and length of leader pipe previously deter mined. Then, using the combination number as found, read directly in Tables 1, 2, or 3 the leader, stack, and register sizes required. ," 6. From Table 8 select the combination number for the return air systen) to cor- Gravity Warm Air Systems rRETURN AIR GRILLE 471 Note: For Types C, D, E, and F return-air systems, reduce the carrying capacities shown in Table 8 by 1 percent for each 4 ft additional length in the horizontal run. Fig. 5. Typical Arrangements of Return-Air Duct Systems respond with the Btu per hour serviced and the type of return air system. Then from Table 4 select the duct and grille sizes, etc., corresponding to this number. 7. Select a furnace having a bonnet output, in Btu per hour, one-third greater than the heat loss from the structure, to compensate for duct heat loss.