The results of a study of hot water production using a solar thermosyphon loop, are reported. A dynamic model has been developed describing the behaviour of the loop consisting of a number of solar collectors and a water tank placed above the collectors. The loop is segmented and for each segment the time dependent mass conservation, momentum and energy equations are satisfied. The solution of these equations is obtained numerically and is compared to temperature distributions determined experimentally. It is found that good agreement can be obtained between theoretical predictions and experiment.