Firstly, install the filling valve to the solar system.
When filling the medium, close the button ①, and open the button ② ③ at the same time. Fill the medium from the left side. When there is medium venting from the right side evenly, it means the medium has been filled up. Then close the button ② ③, and open the button ① .
Note: For button ①, in the lateral direction means it is on open statue,
while in the vertical direction means on close statue.
For button ② and ③, in the lateral direction means on close statue,
while in the vertical direction means on open statue.