There are two 50-gallon systems; one with 20 feet of collector, the other with 25 feet of collector. (Model 5020, Model 5025).

There are two 65 gallons systems: Model 6525 with 25 feet of collector and Model 6533 with 33 feet of collector. Model 6533 was tested by the Florida Solar Energy Centre and found to have the lowest heat loss of any solar water heater

There are two 80-gallon systems: Model 8033 with 33 feet of collector and Model 8042 with 42 feet of collector.