Attic ABS water heater

[Renron]

I found this while "crusin" the web. Sound interesting, any thoughts? Came out of a Fresno CA area Plumbers Assoc. minuites.

The water heating system consists of a 6" diameter schedule 80 CPVC pipe 20' long that is installed in the attic at an angle with insulation on one end. The lower end is insulated for hot water storage. Water is heated in the 6" pipe during the day and feeds the water heater through a series of valves. The water heater does not fire up during the summer. The 6" pipe and the water heater would have to be drained before the water heater would fire up. The combined capacity of the 6" pipe and the water heater is approximately 60 gallons. The system does work during the winter but not as well. The home owner may valve-out the 6" pipe storage system during the winter. This system has an engineered pipe support system stamped by a licensed engineer.

Would 3, 3" pipe work better?

Ron