Test data versus f-chart predictions for two domestic hot water systems

The thermal performance of two solarly heated domestic hot water systems was measured under actual weather conditions. Observations were compared with the performance that would have been predicted by the ''F''chart method. The system chosen combined the collectors of the highest performance commercially available with conventional closed-loop design and a double-walled heat exchanger having an effectivenss of 0.35. The predictions of ''F''chart for domestic hot water solar fraction agree satisfactorily with measured solar fractions. 9 refs.