free heat. build a heat box for $6 and heat 500+sq feet, for free. during sunlight hours, i suppose.
does anyone have any experience or expertise on this claim?
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@holon42 The design on this one isnt the most efficient. I have 4 3 that fit in reg windows and one that sits on the ground 3'x4' there are lots of different designs. They have 12v thermostats and small fans. Using them last 2 winters I reduced heating gas by 66% both years. They do work the larger one so well I have to replace solar fan it had with a 220cfm air mover (6watt) to keep its internal temp below 200 - they draw air from inside & warm it
Id look at several videos before you decide to build one
I use 6' roll flashing which I bend into a V against a back plate of same flashing ( its cheap and AL has good thermal properties)
Painting the surfaces flat black enhance the amount of solar energy absorbed ( Missing in video you linked)
They do work but have to be setup and taken down seasonally.
Wwinters here have lots of gray days where they dont work - so back up heating is needed.
They dont work at night (duh)
I was fancinated by the idea and keep trying different things to make them better ( why there are 4 now) . Id take a picture but in my shed as I havent yet set them up ( do need to soon)
do tag me a photo when you get around to that. i'm sure others would love to know about them too👌🏽