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882 CHAPTER 50 - ,1948 Guide , TABLE 8.. SUGGESTED: SoLAR-HEATER.PeSIGnDaTA3 ; . . ' Dxsiqn It*m .' Based, on .Rats of 30 Gat . ' rSB.DAT FSB PXBBON - . Based on Rats,of, 40 Gal - ..... -- pkbDat pkbPbbson No, of Oecopants InBaddgttfce.;.-jl:. 2 3 : 4 r- 5 - 6 - 7 8 1 ---2 3 4 5 * 6 -: 7 .8 Hot Water Used aiNight,4&i per r pejaon.... - ? *.; :'() 1 V?- | :ts tl5 ;J5 45 ;5 1*16 i . '16 j: 20 20 20 30 20 .20 20 ,20 Hot Water-Used at Night, gal totakii .15 *30 .1-45 -60 -75 i 90 1105 120 20 40 ~ 60 80 -too 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, gaLi...:..;.L 20 40 '59 75 J94 H3 'iso' : iso -95 50 !`75 100 125 450 175 200 Hot Vfater-Cged-During Day, gjallLl. , 15 `30 45 60 '.75 -'90 105 .120 ; 20 . 40 `60 .80 100 '>.20 140 160 Gal per hour____ ~R5 ___________ 4i . 4m '135 169 235 `270 '45 90 135 180 270 315 360 9 13 17 21 26 29 34 6 12 17 23 28 34 39 45 Copper CoS Required: Equivalent length 1 In. coil, ft____ 25 100 50 200 75 300 100 400 121 484 145 580 168 192 664' .-5768 32 128 64 256 96 384 128 5)? 160 192 224 256 64Q -rte '896 1024 Box Else: . Width, ft____ ; Length, ft-- .........'...... -- fl/ 25 4 50 6 75 100 121 145 168 192 7s 1C 10 11 32 64 96 128 160 192 224 256 4 C *8 "'fi K 11 12 12 6 8 11 12.5 13.5 14.5 16.5 17.5 8 cio 12 14 16 18 19 21 Sun Effect and the Design of Solar. Heaters. by H.L. Alt (A:S.H,V.E. :Transacti6ns. Vol. 41. 1935, p. i3i). ; ; : /V circulation lines, ap^snk. A copper coil is more efficient in absorbing heat in the box bift galvanized iron or steel may be substituted depending on the local water conditions, xost. and other considerations- The storage tank must be.able to store sufficient heated water for the night period bf,about 16 hours when the coil ls ho,^ functioning or is operating under such podr sun cdnditions as to male its heating effect negligible. Due to the fact that the no r, period .includes, the night period when little dr no hot water is used , an available, storage of 50 per cent of the average daily usage is considered adequate. Since about 25 per cent of stored hot water cannot be drawn out of a storage tank before the .incoming cold water: reduces, the .temperature of all of, the water, in the tank to an unsatisfactory .point Lfortusage, the equation :for calculating the!Storage7capadtjrof:the.tank becomes: -i ; y-' Q X 0.50 1^ ? S' 0.666(> 0.75 (4) where . ... ...., . ........ .. 5 = storage capacity of tank', gaiions. ' Q= average daily usage, gallons. Thus for. a family of, four persons using an average of.40 gal,of. hot water per person perdaythesizepf the tank.would be:4 personsx.40,`gal x 0.666. or,. 106-gal,; .and the-.nearest'.standard.;sizex of tank,, to this theoretical capacity would be useri. The tank should be .well insulatdl .to prevent, undue loss of heat during the ,i 6-hour period'when the coil is inoperative,: and.it should be located as high as possible in the building (uqder the peak of the roof if such exists) so as tQ. secure a maximum circulation head from the coil. The hot water supply to the house, as shown in Fig. 11, is located at the top;of the tank, which serves to vent the^iir from the tank, through the hqt water faucets, as fast as it. accumulates. ., ....... . , . The coil, should be of, the: retum;bend ; type,^square or; Slightly rec^l tangular in form, and should have the pipes running east and west;:;with the coil on the south side of the building where.it can receive the full suh Water Service 88$ effect alt day .long without shadows from the-buildingyitself; Of from adjacent obstructions such as trees or other structures.' The coil should 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 ifth, .fittingsto'matibh ;tfie materials of the coil, c rculation lines, and tank;. .The coi) shohld be inclined as shown in Fig. 12 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). 'This1 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 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 tb reflect the heat, while the cbil should be painted black to absorb the heat; The'box heed 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 fcbil 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 8 may be used with some judgment in selecting the size of solar heater coil and box ,for a particular application. These data are based on consumptions.of 30;and40 gal;of hot water per day per person. REFERENCES _ M?f*?<isof Estimating Loads in Plumbing Systems,.)>y R. B. Hunter {National Bureau of Standards Report BMS85. 1940). Plumbing Manual. Report of the Subcommittee on Plumbing,' Central Housing Committee on Research; Design and Construction (National.Bureau of Standards, Report BMS66. 1940) Water-Distributing Systems for Buildings, by R, B..Hunter{.National Bureau of Standards, Report BMS79. Distributing.Systems for Buildings, by R. B.tHunter {National Bureau of Standards, Report BMS79. p. 6-9.) (Charts extended to flow of 0.39 gpm). . ' . Plumbing Practice and Design. by.SvendPlum.(JohnWiley,and Sons, Inc.. 1943). .; Use of Solar Energy for Heating Watirr.'by F. A. Brooks, Smithsonian Institution, Washington. D. C". ; BIBLIOGRAPHY , Laundry, Kitchen and Hospital.Equipment;' by H. C. Russell (A.SIHW.E. Trans actions, Vol. 35, .1929, p. 45). Water Consumption, Cost and Savings, by G. C. St. Laurent (AmcricanHotel Association, Hotel Engineering, Vol. 1, 1940). .. - , Water-Supply Piping lor the Plumbing.System, by F. M. Dawson and A. A. Kalinske (Technical Bulletin No. 3, National Association of Master Plumbers).