i googled "batch water heater" but didn't find the plan that I used. I'll take a look for it tomorrow on my computer and post it if I can find it.

A couple of things tho. With 4 kids, we used to use A LOT of hot water. Also, I don't know how much of those savings are attributable to the new windows and how much is the solar hot water heater.

But the numbers are accurate, that much I do know.