Solar hot water heater......
 

Actually starts half way through this guys video. Was wondering why I had him as a subscription, last couple vids almost put me to sleep with his voice, yet not killing the messanger, did not un subscribe, and , cool, a pretty intersting video. Simple to make, may draw up some plans of my own, and grab some misc, materials ( think I can get the used water heater from the local scrap yard for the price of gas to go pick up) may come in handy in the event.....

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Re: Solar hot water heater......
 

Hot water heater? If the water was already hot it wouldn't need to be heated.
Interesting concept though.
Kinda want to try it.