Summary: Transition boiling data was taken with an improved flow loop, to explore the influence of loop characteristics on rod temperature fluctuations the transition region was found to be much smaller than for comparable conditions with a different loop. Also the amplitude, and frequency of the temperature oscillations, were significantly less than before. These results indicate that loop characteristic and flow disturbance parameters play a prominent part in governing the transition temperature fluctuations. Additional two-rod transition boiling data are presented. The results include data taken at high wall temperature levels during a demonstration test at low steam qualities, and the effect of a change in rod spacing on heat transfer performance.