[AndrewJ]

Daox: I think the radiator thing would work great as long as you're using it for hot non-potable water. Many radiators are made with some unsavory materials (like lead) and I wouldn't want to drink water that's been heated up through a radiator...

dremd: Awesome score with the solar water heater! My dad has been talking about getting a solar "batch" water heater like yours for a while, but I don't think it'd be such a great idea in Missouri where the winters are (way) below freezing.
I remember reading a book about solar hot water that said that in the 20's the vast majority of hot water in the state of Florida came not from gas or electricity, but from solar water heaters.

How far we have fallen...