Now I wouldn't purport to be an expert on setting up a geo thermal heating and cooling system in a greenhouse, but after watching a number of videos, reading blog posts and talking with some people I feel like a know enough to do what I want to accomplish. What is a geo thermal heating and cooling system? Basically it is a way to use the earth to heat and cool air in order to heat and cool a greenhouse or some other space. Living in Midway, Utah now, I have challenges with temperatures that come with living in a mountain valley at 5,600 feet. I'm actually only about 200 feet higher than where I was at in Denver, but the average day time temperature is about 5 degrees cooler during the day and night and that makes a big difference, particularly with giant pumpkins. 45-55 degree nights is not ideal for packing on the pounds. It makes for nice sleeping however.
So what I have to do is make the pumpkin plants think they are in Napa Valley, Ohio or Rhode Island. The greenhouse I will build will help with that. That will help warm the plants up more quickly in the early morning and will get the humidity up a little. It doesn't do much to keep the plants warm at night however.
The corrugated pipe that you see in the picture below were buried about 2 1/2 feet down in the ground. One one end of the pipes will have a tube that will go up to the top of the green house and it will have an inline fan hooked to a thermostat that will blow the hot air down into the tubes at a high enough volume to circulate the air volume in the greenhouse. When the air goes down into the ground it will warm the soil, which is great for the roots and will get the biology in the soil going. In return the air will be cooled by the earth as it passes through the pipes and then will be blown into the greenhouse, cooling the air in the greenhouse. In all of my research, this is the most efficient way to heat and cool a greenhouse. If it were up to me I'd heat the greenhouse at night with a propane heater (i.e.expensive), but my wife is mean and won't let me. Lol
I also mention that this system will also heat the greenhouse. Another thermostat will kick on during the night, when it gets too cool and the reverse will happen. Cooler air will be blown into the pipes and will be heated up by the earth, that has stored the heat from the heat of the day and on the other end, warmer air will be blown out.
I've also purchased an number of soon to be black water barrels that will be on the southwest side of the greenhouse. Those will soak up heat during the day and then at night will release the heat into the greenhouse. The guy I bought the barrels from, who has a greenhouse, said he has checked the temperature of the water in the barrels during the day and 85 degrees is pretty common for him.
All of this together I hope will make for some giant pumpkins in 2017.