There is a need to determine the comparative performance of different types of solar water heating systems. Two separate generic types are competing for the domestic solar water heater market in Florida. They are the integral collector storage (ICS) systems and the more conventional flat plate systems, which incorporate a circulation pump.

Tests were conducted on four different ICS systems and four flat plate systems. Comparing the performance of as many as eight systems in simultaneous outdoor tests presented a number of problems. ICS collectors are usually employed as preheaters, and they are commonly plumbed in series with the backup water heater. Flat plate systems, on the other hand, are plumbed with the collector and pump in a loop that is parallel to the backup heater. Because of these basic differences, sensor location and the pattern of draw (hot water usage) are critical to accurate evaluation.

This paper discusses the problems encounteered when simultaneously testing the performance of significantly different collector systems under outdoor conditions. It also presents a number of useful solutions to these problems. Some results are presented but the emphasis is on the problems encountered.

Units: I-P