Document wKyJODvEDM5qjkom5yV07L61D

CHAPTER 19 1954 Guides 458 an.i *-'**> ?"22=-; Gravity Warm Air Systems 459 16 i I - r--r-T-~l | , , . ___ ___________ Notes: When floor registers are used on second story rooms, include the equivalent elbow .resistance for theCcroomssb-ionvaetriocnonNnuemctbioenrsas21shaonwdn23inasFsigh.o2w- n in Tables 2 and 3 are composed of narrow stacks for narrow For Combination No. 21, the capacities are the Btuh deliveries shown for Combination Nos. H or " stud spaces. muFltioprliCedombbyin0a.8t3io. n No. 23, the capacities are the Btuh deliveries shown for Combination Nos- 12 or... multiplied by 0.83. Standard work sheets to facilitate design according to the recommended procedure, are available from NWAH & ACA. Table 8. Return Air Com bination No. Duct Diam. In. 31 10 32 12 33 14 34 16 35 18 36 20 37 22 38 24 Return ^Carrying Capacxty-BtuhS^ceb Type A BTUH 11.300 16.300 BTypes Cand BTUH 9,500 13,700 Type D BTUH 7,800 11,300 Type B BTUH 5,000 7,200 Type F , btuh 7,800 11,300 Brnm-" Aw Cobbib*tio> 31 32 22,200 29,000 18,700 24,400 15,300 20,000 9,800 12,800 15,300 20,000 33 34 36,700 45,300 30,800 38,000 25,300. 31,300 16,200 20,000 25.300 31.300 35 36 54,800 65,200 46,000 54,800 37,800 24,100 45,000 1 28,700 37,800 45,000 37 38 T"-- h Tin* ( Tjrpe.F Note: For Types C, D, E, and F leturn-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 op Return-Aib Duct Systems Design of Extended Plenum Systems The extended plenum system of gravity warm air heating employs horizontal ducts in the basement leading from an enlargement or extension of the customary plenum to the risers which distribute the conditioned air to the various rooms. Extended plenum gravity systems have been satisfactorily designed and installed in small compact houses where the heat losses do not exceed 65,000 Btuh. The dimension from the floor to the bottom of the joists should in every case be at least 7 ft. To design such a system the procedure is the same as for the conventional system already described in this chapter. It is understood that the length of leader pipe is measured from the register to the furnace. For takeoffs, use standard fittings designed for Fig. 6. Typical Basement Line Drawing