An experimental study was carried out on a unidirectional two-phase coil-loop tbermosiphon utilizing R-11 as its working fluid. The evaporator consisted of three coplanar tubes joined to a vapor header normal to the tubes. Each tube had a separate water jacket. The condenser was similar in design. The system was designed in such a manner that the evaporator and condenser could, independently, be translated vertically, be rotated in the vertical plane about a horizontal axis, and be inclined from the vertical while maintaining their vapor headers horizontal. It was found that, although the total heat transfer rate for the three tube system was not reduced by differences in the source fluid temperatures surrounding the evaporator tubes of as much as 40 percent of the source-sink temperature difference, or by static charge differences of as much as 26 percent, substantial differences did occur between the individual tubes.