I read an article on storing heat by using rocks inside barrels of water. If the water is heated and the rocks in the container are heated it would provide heat at night. The containers are buried below ground. Also I used a Fresnel lens from an old flat screen TV to heat the black pipe in the glass like a magnifying glass focusing the lens focal point on the Black pipe increasing the radiant heat. It seems to work well. I'm going to try burring the barrels or lining the well wall with a plastic RCP and fil the bottom with gravel up to a certain point and hope that the rocks will retain heat to help facilitate the night radiation.
