On Sat, 16 Jun 2007 18:03:03 -0600, Jack Schmidling wrote:
We just purchased a Clear Span Hobby Greenhouse and wonder if anyone
else has had any experience with these.

We are still putting it together after 3 days of fighting crappy
hardware, lousy instructions and generally poor design.

We don't scare easily but I sure pity anyone with any less fortitude and
tool knowhow.


Jack, I don't know this company, but if you're really stuck, you might
try popping in at HGA-L, the home greenhouse association email list --
there may be someone else that has experience with this design.

The new one uses double walled polycarbonate which should insulate a lot
better and wonder if anyone has any idea of the possibility of keeping
this warm enough in winter with a one KW heater.

1KW root zone heating may be enough, depending on your climate and
the crops you're growing, and what you're expecting. Consider also thermal
mass to help carry you through the night hours.

There's a USDA program that allows you to "build" a virtual greenhouse and
test it for your parameters. I'm not sure if it can handle calculations for
a small house or not... won't run on the o/s I use.
http://www.ars.usda.gov/is/pr/2007/070607.htm
http://www.ars.usda.gov/services/sof...softwareid=108

Another possibility, again depending on your location and climate, but
a distinct possibility given your inquisitive nature and mechanical aptitude,
would be to add a solar water heater type design, possibly using a PV pump.
The new vacuum solar collectors are very efficient, but I think even Ye Olde
1970's homemade designs might be efficient enough.

One hint for small greenhouses in winter, if you can: Water with room temp
water rather than freshly pumped. A simple way is to fill a bucket or carboy
near the GH roof, and then let that warm in the house, and water with the
warmed water by gravity.

Kay