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784 ' Chapter 46 1945 Guide be placed as low as possible in relation to the storage tank level, such.as on a porch roof, the roof of a one-story extension or, if necessary, even on the ground. Both the . coil and the circulation lines should be designed to facilitate the circulation flow as much as possible-using long radius copper fittings or recessed galvanized iron fittings to match' the materials of the coil, circulation lines and tank. The coil should be inclined as shown in Fig. 6 so that the north end is raised above the south end to secure an angle with the horizontal of about 53 deg. This will result in the inlet end of the coil being on the south side (or bottom) and the outlet end being on the north side (or top). This will satisfy conditions along the 30 deg N latitude which includes the portions of Florida and Southern California where these heaters are most frequently used. The hot box is usually constructed of wood on the four sides and . Table 4. Suggested Solar Heater Design Data3 Desigh Item Based oh Bate of 30 Gal PEB DAT FEB PBBSOH Based oh Batb of. 40 Gal FBB DAT PEB PEB80H No. of Occupants in Residence.____ 1 2 3 4 5 6 7 8 1 2 3 4 5 6 ' 7 8 Hot Water Used at Night, gal per - pgsoa__ _____ . 15 15 15 15 15 15 15 15 20 20 20 20 20 20 *20 20 Hot Water Used at Night, gal total, 16 30 45 60 75 90 105 120 20 40 60 80 100 120 140 160 Retained in Tank, 25 per cent, gal-.... 4 8 11 15 19 23 27 30 5 10 15 20 25 30 35 40 Tank Capacity Required, gal______ 20 40 59 76 94 113 130 150 25 50 75 100 125 150 175 200 Hot Water Used During Day, gal__ 15 30 45 GO 75 90 105 120 20 40 60 80 100 120 140 160 Total Water to be Heated: Gal per 8 hr period--__ Gal per hoar.-............ 35 70 104 135 169 203 235 270 45 90 135 180 225 270 315 360 4.5 9 13 17 21 26 29 34 6 12 17 23 28 34 39 45 Copper Cofl Required: Surface area, nq ft.............. .... ....... 25 50 75 100 121 145 168 192 32 64 96 128 160 192 224 256 ,: -.Equivalent length 1 in. co3, ft___ 100 200 300 400 484 580 664 768 128 256 384 612 640 768 896 1024 Bos Size: Area, sq ft....-- WidtMt___ . Length, ft_____ _ -- . 25 50 75 100 121 145 168 192 32 64 96 128 160 192 224 256 4 6 7 , 8 9 10 10 11 4 6 8 9 10 11 12 12 6 8 11 12.5 13.5 14.5 16-5 17J> 8 10 12 14 16 18 19 21 aRnn Effect and the Design of Solar Heaters, by H. L. Alt (A.S.H.V.E. Transactions, Vol. 41,1935. p. 131). bottom, and is insulated. Over the top of the box glass sash are placed and the box should be constructed as near air-tight as possible. The interior surfaces should be painted white to reflect the heat while the coil should be painted black to absorb the heat. The box need not be deeper than necessary to house the coil and to protect it from the weather. The addition of a light gage copper plate on the bottom of the box to which the pipe of the coil is soldered, for good metallic contact, will add to the amount of heat received by the coil due to the fact that this plate will receive all of the sun rays which fail to directly strike the coil. The heat from this source is transmitted to the coil through the plate instead of by heating the air surrounding the coil and from which only part of the heat enters the coil, the balance being transmitted through the glass sash. Design data given in Table 4 may be used with some judgmeht in .selecting the size of solar heater coil and box for a particular application. These data are based on consumptions of 30 and 40 gal of hot water per day per person. > Hot Water Supply _ 785_ , ______________________________________ : -- FRICTION LOSS IN WATER SUPPLY PIPING Fig. 7, showing friction loss in fairly rough pipe, has been reproduced from Fig. 4 of Building Materials and Structures Report BMS 79, Water Distributing Systems for Buildings, by Roy B. Hunter, National Bureau of Standafds. For friction loss in tubing, as well as in smooth FRICTION LOSS IN HEAD IN LBS PER SQ. IN. PER 100 FT. LENGTH . Fig. 7. Friction Loss in Fairly Rough Pipe and rough pipe the reader is referred to Figs. 2, 3 and 5 in the same publication. REFERENCES Laundry, Kitchen and Hospital Equipment, by H. C. Russell (A.S.H.V.E. Trans actions, Vol. 35, 1929, p. 45). Water Consumption, Cost and Savings, by G. C. St. Laurent (American Hotel Association, Hotel Engineering, Vol. 1, 1940). Plumbing Practice and Design, (1943) by Svend Plum (John Wiley & Sons, Inc.).