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8000 BTU is about right. It's impressive that you actually got that water to evaporate from the roof in a decent amount of time in Atlanta though, since it's so humid. I'm not sure that it does much, since either your roof or your attic floor is insulated.

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A gallon over a big enough area, with a roof that's dark, in 90+degree ambient temperature and direct sun... evaporates within a few minutes. Sometimes < 1 minute by visual inspection, anyway.

re: "doing any good", yes, that's hard to say. The ROI may not be for years, if ever. It was as much a "I have an idea,let's see it through" project as a real money saver.

The attic is insulated, and with a radiant barrier, to boot.

Yeah, a dark asphalt roof and direct sun would do it, as I've observe in my parents' house in Houston. You're also right the the ROI is probably zero or negative since your attic is insulated and has a radiant barrier so the temperature of the roof itself is close to irrelevant.

> dark asphalt roof and direct sun would do it

But if you were going for cooling, you wouldn't go for a dark asphalt roof.

HOA. Not much choice. We got the lightest we were allowed.

Yes. It was a fun project though.

The controller app is a bash shell script. :-)

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