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Has anyone ever used a "Heat Grabber"

The Mother Earth News newsletter just came and there's an article about this interesting doohickey:

What do you think? I'm intrigued, but not sure how effective one might be.

Tags: alternative, heating

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Replies to This Discussion

Permalink Reply by JoyfulC on October 7, 2009 at 11:43am

I'd be willing to give something like that a try. Even if just out on the (unheated, uninsulated, but enclosed) sun porch. It wouldn't need to be all that warm -- just warm it up enough to wrap up in a blanket and read, maybe sip some cocoa on a sunny but frigid winter day. I'm not sure where we'd put it for the overgrown bushes surrounding the porch, though. Hmmm....

Neighbours down the road have built some sort of similar contraption from pop cans spray painted black. My husband had the link to the instructions. I'll ask him about it.

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Permalink Reply by Mitch Amiano on October 20, 2009 at 9:32pm

I think this can work given a sufficiently well-lit side of the house. There are commercial units which work on the same principle of convection: http://www.cansolair.com/index.php.
You can find instructions on Web sites for various designs: http://www.ehow.com/how_5033374_build-solar-heaters.html
A similar sized unit was tested at RIT for pasteurization: http://edge.rit.edu/content/P07401/public/Home

I'm punting on most of these calculations, but under direct sun a 1 square meter area area gets about 1000 watts of power. You're going to lose some to re-radiating heat, but let's pretend you get in the region of one kilowatt for four hours (between 10am and 2pm) and ignore the rest of the time. So you've got 4kWh of energy. A kilowatt-hour is about 3.41 kiloBTUs, so you've captured about 13,640 BTU of heat, about the power of a small kerosene heater.

Dang, that would be a pretty good deal, especially if the units could be put together at a low cost. Sounds like a good project.

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Permalink Reply by Torry on October 20, 2010 at 4:56pm

I've seen solar hot water panels rigged up to the old-style radiators...both of these work well, they won't heat the entire home, but will take the edge off the heating bill.

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Permalink Reply by pelenaka on April 20, 2011 at 12:01pm

From what I've read on different sites people who built & used them are pleased.

As Torry wrote it won't heat your whole home but hey it's free heat. There's a good 3 month or more portion to the heating season where we could get by with just these two rooms being warm enough to complete our morning routine.

This is the year we're building a few, one each of the bathroom & daughter's bedroom which receive the most direct sunlight.

I figure that it my daughter's can wake up to a warm room and we all can stop dreading the "cold throne", it will be worth it.