I've built a cold frame where the entire glazing opens when the inside temp
rises. The key is not to use glass over wood frames but Lexan glazing sheets
you can find at any big home harware outfit. Amazingly lightweight, all
clear. Minimal frame needed.
The openers are British and can be found at LeeValley.com in the gardening
section. if the link is wrong do a search for LeeValley Tools in Canada. I'm
sure the gizmo is available in the US
They open progressively so the "lid" will not be "fully opened" or "fully
closed". They react to temp so more temp= more travel. Max travel is 14" or
thereabouts. Load is something like 15 pounds. Their "sensitivity" is
adjustable so you can keep more or less heat in.
Would gladly supply more info if required. Might be able to sketch then scan
something for anyone interested.
No pics 'cause up here a strange white powderee stuff covers everything for
another couple of months!

Mitch from Montreal
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"Bobbyc28" wrote in message
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Not Familiar with a thermally activated vent. Who sell them?

Thanks Bobby