According to the specs the 47mm tube is about 5 liters, but it has been eliminated
The 58mm tube is about 8 liters, I mean the net capacity available
This is the most. In this way, the top brands have large water tanks, ours is a 470mm diameter water tank, others have more than 500, which is a bit bigger than the one above, hope this is helpful! I manufacture solar water heaters, 871333782