Sunday, February 10, 2008

Double Glazing

This past weekend I finally figured out how to put a second layer of glazing on my greenhouse. The spacing between the layers is about 1 inch but some of the separation isn't that consistent. Looking at the temperature data for the last 24 hours the difference between the inside and outside was at least 2 degrees Fahrenheit and at most about 20 with a maximum inside temperature of 70 and a minimum outside temperature of 30. The only other solar features that could affect the temperature inside was a 30 gallon green garbage can full of water. Hopefully tomorrow I will be turning the air circulation back on if I finish getting the ground tilled.

Here's how I put the double glazing on.
I nailed 3 - 1 3/4 thick boards along the length of the green house. One at the peak, front top edge and front near the ground. In each of these I drilled holes for a 1 inch pipe to set in. This is outside of the existing plastic. I created a pipe framing that covered the existing plastic, this will keep the layers separated. The pipe in the ceiling has a T in the middle of it to help give it a little bit of rigidity. Next I measured the plastic and rolled it out and cut it to length. Folding the plastic back on it's self so that it could easily be laid on top of the greenhouse and stretched out. After stretching it over the back I placed a few staples in it and then stretched it down the front edge. Coming to the back again I added a few more staples in the existing board that secures the plastic. Next I place a strip of wood so that it would secure the plastic to the board near the ground on the front for the greenhouse. After securing this I moved to the back and did the same and secured the plastic to the top board that also holds the pipes in place. Next I carefully worked the ends of the greenhouse so that the plastic was spaced away from the existing plastic. I believe that currently this is the weak link in my design. I'll have to come up with a better way to keep the two layers separated, but until then this should work. Hopefully I'll get some pictures posted soon of exactly how I did this. Until then let me know if you have any questions.