coolrobby2003

Can any-body give me the ingredients (aka-directions) for using a small fresnel lens to heat a 4 foot x 8 foot double payne glass greenhouse? I'm sure u would need some sort of heat collector-RIGHT? (but what?) This will be sitting out in the Very Cold Illinois Winter!
(bottom and sides well insulated)

Chironex

Good question, you could try the beer can solar collector on youtube. Another I have seen uses pennies glued to foam board, then spray-painted black matte, then encased in foam board with a plexiglass front. You could substitute the fresnel lens. Add vents to the top and bottom of the enclosure to allow heat movement.

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Scot

lorax

What is the wattage and lens size of the Fresnel? Is it a mini-me, or something larger? Which company made it (Source 4, LekoLite, etc.) If you know, I can give you an estimate of the heat output for it...

Personally, I'd make an aluminum-can heat collector, as Scot suggested, and focus the main beam on this - if it's bigger than a mini-me, then you can select hard or soft beam; the hard-beam option concentrates more heat than the diffuse (kind of obvious when you think about it.) Depending on the size of the instrument and the wattage of the lamp, you'll want to place it about 1-3' away from the collector. Again, if you tell me a bit more about your Fresnel, then I can tell you more accurately what you can and can't expect from it...