In order to put a large 2500 litre tank in greenhouse, the pavement was done.
We were extremely lucky. In order to clean up construction site I was working at, I got enough basalt groats and fine sand to make bed for pavement plates (also used). Dirt was removed, the felt placed under groats and then compressed. Used concrete plates were layed on fine groat. Al gaps were filled with fine sand.
It was time to get large water tank. We had it in our house for heating oil storage. We didn’t need it any more, because we heat our house on solar energy and wood from our own forest. It was so tightly placed between the walls, there was only centimetre on each side, but we managed to get it out 🙂
Eva painted it black, so it will absorb more energy (heat) from sun. Eva did all the painting in greenhouse to!
The main idea of the tank is: Large black tank is full of water. In sunny days the temperature of water will rise and in cold days and nights it will radiate that energy inside greenhouse. Example: 2500 litres of water have 20°C during day. Next morning water have only 18°C. All the energy that was taken from water in tank is in greenhouse air now. That would be 21 MJ!
Well I have to make some measuring of actual temperature differences between evening and morning to get the right numbers.