no scale, high efficiency
Water in the tank wouldn't be used just to heat the coil, the water in the tank will keep hot and no scale. The vacuum tubes will be kept clean, and system has a higher efficiency than normal system.
Total 3 valves in whole system only, very simple and safety, maintenance free.
Because of all hot water in main tank, the feed tank won't be frozen. It can be working well in -10deg.C. - good performance in rainy & cloudy days
When tap water comes in and out, it will be just 3deg.C less than water in tank. Viz. if 90deg.C in tank, the outlet water will be at 87deg.C after exchanging.
If tank water is 90deg.C, and you catch rainy days, no problem, if you use 50L 40deg.C water per day, you can keep getting such hot water for 15 days!!
The electric heater is only backup, we don't use it anytime practically, except in winter.
Because the water in tank doesn't be used, in fact the circulation is not only water in the tank but also water in the tube. So for example 300L, actually it has 400L in whole system.