Hot Attic = Hot Water?

Homestar Plumber

What is the best way to use my hot attic to provide me with a hot shower? I've thought of using an indirect water heater heated ONLY with the attic heat , but I am worried about legionellae bacteria as the water will never really be that hot and certainly not for a sustained period of time.

Kevin_in_Denver_2

RISA= Roof Integrated Solar Absorber

Hot attics can be water heaters, the jury is out if they are cost effective.



Attached is a good report.

hot_rod

Solar Attic

I've seen this product advertized before. No reason you couldn't build one to do DHW, and ventilate the attic.



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Kevin_in_Denver_2

Great Find, Rod

No doubt hot attics are a problem, and this is a very simple way to cool the attic and heat some water.



I would think that any hydronic unit heater or fan coil would work. A solar-type differential control with a tight delta T could be the controller.



One issue is that in cold climates, most attics are vented and might freeze. The solution is drainback of course, so the device must be designed to empty completely.



I think drainback helps solve the legionella problem as well, because you don't have the potential for long loops of stagnant water. All the water drains back to the preheat tank. From there it goes to the backup water heater, which will top off the temperature, and kill the bacteria.

hot_rod

and a condensate pan

to drain any sweat from cold water hitting a hot coil. I think a Modine or any hydronic unit heater would work.



It seems a lot simpler than tubing the roof, plus the air moving feature.



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