SOLAR ENERGY FOR WATER HEATING — BROOKS 



179 



the total length of pipe in* the single-coil type is so long in compari- 

 son with the effective riser height that thermosiphon flow is unduly 

 restricted and provides only very small quantities of excessively hot 

 water, the solar-absorber heat losses are large because of operating 

 at unnecessarily high temperature. One can then improve the eflSci- 

 ency by paralleling the absorber pipes to reduce the length of each 

 line and also to divide the flow into multiple paths. 



Figure 9 shows the fittings and pipe lengths for three-parallel- 

 pipe absorbers. The combination of fittings shown gives the closest 

 pipe spacing possible and a practical covering of absorber area. The 

 methods shown of making the terminal connections also permit the 

 use of all equal-length pipe runs from end to end. In the three-pipe 

 systems one union is located at the opposite end of the box, top and 

 bottom, to preserve the equal-length feature of the main pipe lengths. 

 The diagram, though not complete, gives the unit-section dimensions 

 so that the full installation can be easily sketched. Such pipe sys- 





i?p/>roj( JO' x//o. af 4//7/^ sec^/o/3s. 



Figure 10. — Absorber piping for six pipes in parallel using branch T terminals. 



197855 — 40- 



-13 



