DIY green (and cheap to run) garage/shop heater

Couple of things I am going to do different...maybe. First I am going to use convection to help with air movement...intake on the bottom and output at the top. The second I am not sure about...seeking a bit of wisdom to help me decide. Would the heater be more efficient if the interior insulation were to be left reflective to concentrate heat on the tubes or is the black paint inside helping to absorb heat and transfer it to the ducting. I am also considering getting some aluminum flashing material and making reflectors to put under/around the ducting to concentrate and reflect light onto them. Any ideas?



https://sites.google.com/site/glenssolarheater/

 

Hmm...dont know. In most workshops its the concrete floor that stays cold all winter. I would think that a system which heats the floor would make a mighty nice boat shop.

In general shops are cold because when working you make so much dust and toxic fumes that you must ventilate the shop.

Locally they build a tent around the boat inside the shop... theshop is cold..inside the plastic tent its warmed by solar heat, hot water, panels on the roof of the workshop to allow resonable cure times on the variuos Goo's

 

Two tips, absorption and retention. You don't want reflective materials (unless you use a parabolic or cylindrical reflector behind the tubes), you'll just bounce out potential energy transfer. For the retention aspect, consider double pane glass, maybe stealing half of a sliding door. With out insulated glazing, most of the sun's energy will just rise out. Insulated glazing will prevent this. You can use regular glass of acrylic sheets too, but it's less efficient then seal, inert gas filled glazing. Of course you don't want any UV filtering coatings on the glazing. BBQ paint seems to work the best and you'll need it on some days as you can generate a fair bit of heat with these things, certanily enough to cook regular paint right off the pieces.

Look up back issues on "Mother Earth News". The tree huggers have been barnyard engineering these things for generations.

 

I had thought of using cylindrical reflectors but looking again at the amount of space between the tubes (3/4"), I doubt it would be useful. I expect that more tube area is better than some extra reflected light. Good idea on the double pane...but only if I can get it cheap (used). I saw stove paint at the box store...good to 1700 degrees. I'm wondering where I can get the foam insulation that will withstand 200+ deg. temps. Oh...and seeing as I can barely afford to put something like this together a heated floor isn't in the cards. Not all work needs that much ventilation...

 

How's it supposed to work? Where does it go, roof or wall? What's the top and bottom? Convection will get stifled at the loop end. The tubes need to be black.