My initial plan to make a 10-20 liter device had failed, and here’s why:
I originally planned to install the latest generation water level control floating valve in the booster box.
They are compact, neat, hard-duty, modern looking, unlike the classic float valves installed in toilets.
However, as I was digging deeper into the matter I found out that modern water level valves can’t be used in the booster box.
They are compact and look fancy, but to make them work properly the pressure in the system should be at least 0.2 bars, while old floating valves have zero water resistance.
Taking into account that we are looking for the water pressure we had to switch to classic design floating valves, which enforced us to increase the size of the booster box up to 40 liters.