greenhouse running abs pipes under greenhouse dirt?

I am wondering if anyone has ever tried to warm a greenhouse/coldframe by blowing warmed air through piping ran under the soil and then vented into the greenhouse? My garden is a 8 foot x 32 foot raised bed, that has a pvc coldframe covering it, to make a single layer greenhouse. I have a 6 inch inline fan to pulls warm air from my house into the garden. The way I have it now, the fan blows from only one end only making the other end quite a bit cooler. I am wanting to balance out the temperature inside, so I am going to hook up the fan to 4 inch abs piping and vent it over 3 or 4 smaller vent holes (2 inch). I was thinking of maybe burying the pipe and looping it 3 passes under the garden (one pass under each of my rows) before venting into the greenhouse. Is there any benefit to doing this? I was thinking that maybe this would help to warm the soil faster in the spring and I could continue to pump air through the soil in the summer to help with cooling. The 3 passes would be around 90 feet long and then a 4th pass that would have the 3 or 4 vents coming up to the surface. If I had the space, I could see this working on a very large scale burying pipe below frost level and having several hundred feet of piping, to do a geothermal type application. In my yard, I am limited to not digging down, due to buried lines.
 
 
 
20170713_174618.jpg
 
Using geothermal isn't really about warming the air, it's about using the earths temperature at the depth you bury the pipe. Depending on your winters and summers makes a difference in how deep you have to go. It will certainly help you but is it worth the cost to install it?
 
Check out this video. 
https://www.youtube.com/watch?v=ZD_3_gsgsnk&feature=youtu.be
 
Its just me but I think the concept is great....except for using heated air.  A recirculating closed warm water system would give a greater efficiency of heat transfer.  Insulate all exposed pipe, and the water reservoir, and let the soil "insulate" the exposed  buried pipe. :P  Ive been thinking of a similar setup.  I plan on using a 110v hot water heater element or two???  and a digital temperature controller (off amazon) and a water pump.. Should be pretty easy to maintain a reasonably constant temperature in winter....I hope. 
 
Back
Top