re: greenhouse solar fan ?
2 jan 2001
>jade mountain sells ($200) something like you describe. they claim they
>have a 12v fan which produces 1200 cfm using just 0.04amps (i.e. 0.48
>watts). their claim seems hard to believe...
wes at jade mountain says he tested this fan with an e-meter, and
the description should read:
>low amp draw, high air flow and cooling! with just 0.4 amps, 1200 cfm
>on the low setting, 0.8 amps, 2000 cfm on medium and 1.5 amps and 3000
>cfm on high. light weight, quiet, direction-adjustable - this fan has
>it all! includes alligator clips for easy connection to a 12v battery.
> does anyone have experience with the 10 watt, 12" solar fan advertised
> for greenhouse use at various places? advertised at full sun and
> speed should reach max of 550 cfm. i would be adding this during new
> construction of a 12' by 24' rigid, polycarbonate greenhouse.
you might hinge a low polycarbonate panel on the east endwall and a high
one near the west peak, and use a couple of pulleys and jade mountain's
$53 fc115 thermofor adjustable heat-activated (0.00 amp :-) damper actuator
instead. the catalog says they will open any hinged window up to 15 pounds
a full 15".
in full sun, the greenhouse might gather 0.8x250x12x24 = 57600 btu/h.
a 3000 cfm fan would keep it 57600/3000 = 19 f above the outdoor temp.
a 2'x8' vent at the top and bottom with 8' of height difference could
move 57600 btu/h = 16.6avsqr(8)dt^3/2 with dt = 18 f and 3190 cfm...