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re: thermal shutters
25 jan 2003
chrisachroisdk wrote:
>> bubblewalls seem like a better alternative now. fill the space between two
>> glazings with air during the day and soap bubble foam at night. one shop-vac
>> can foam an entire 100' greenhouse, and during the day the bubbles collapse
>> to less than 1% of their nighttime volume as soapy water.
>...i have long (mistakenly) lamented the beadwall as impractical...
>it would now seem rumours of its demise were exagerated...
well, zomeworks doesn't make them anymore.
>it might be practical & economical to envelope the existing (passive
>solar) lean-to greenhouse with a similar one. with bubbles in between
>the two glazings...
that's what is done, sort of. commercial greenhouses usually have 2 layers
of plastic film glazing stretched over 1 hoop frame. a small blower inflates
the space between them during the day. to add bubbles, make a trough full
of 10% detergent solution near the ground on each side with a 2" pipe full
of holes just underwater and blow air into the pipe to make bubbles. a 2"
hole hear the top of the greenhouse can act as an air return to the blower
or shop vac. a piece of window screen over the hole can easily pass air but
distort with bubbles, turning off the blower via an outdoor microswitch.
nick
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