Hot House

Wow, now that we have closed everything in, it gets mighty hot in the greenhouse when the sun is beating down.  This thermometer that came with my kit is designed to register the high and low temperatures.  On the right is a regular thermometer that marks the hight temp.  At the time I took this photo, it was about 92 degrees F, but the blue indicator line above the mercury shows the high temperature, which reached about 117 degrees F.  The gauge on the left is the reverse of normal, when the temperature rises, the mercury (if that is what it is) falls.  So the blue indicator marks the low temperature, which was about 72 degrees F.  The button on the center of the thermometer resets the blue indicator lines.  

Now, the reasons that it got so hot in here is that (1) the roof vents were closed, (2) the fan was not running since there is no electricity yet, and (3) I don't have any shade cloth over the greenhouse.  

Here are the automatic roof vent openers that we just installed today.  The way that it works is interesting.  There is a cylinder that is filled with a paraffin material which expands and contracts with the temperature (parallel and below the springs).  When the temperature rises, the material expands and drives a piston out the end, which has a screw end on it that prevents the piston from sticking out any further.  This causes the hinge to open up against the tension of the springs.  As the temperature falls, the springs compress the contracting material and it closes the hinge.

Here you can see the vents have opened up.  The temperature is a little over 90 degrees inside the greenhouse at the time I took this photo.  I had put the openers in the refrigerator before we installed them so that they would be closed all the way, in this photos, they were still in the process of warming up and opening.