I am installating a greenhouse which is 30meters long and 10 meters wide. I would like to use about 3 rocket mass heaters to heat the soil. What type of pipe to you recommend I use that is fairly cheap Metal, Asbestos, etc? I need about 100meters of pipe, because I want to install 3 mass heaters outside the greenhouse and run 3 pipes under ground to heat the soil surface for the plants on top. How deep must the pipe be? Your advice will be greatly appreciated.
