How to open the exhaust valve of the floor heating water distributor?

The exhaust valve of the floor heating water distributor needs to close all other valves of the floor heating, and then open it in a certain order. Otherwise, the exhaust valve can only discharge the heating water but not the internal gas. It only needs to be opened counterclockwise. Rotate, the specific operation steps are as follows:

1. Close all valves on the floor heating valve group, including the main valve, branch valve and air release valve. ?

2. Open the main water inlet valve and the water inlet branch valve. ?

3. Open the return water release valve. ?

4. Open the first branch valve of the return water. ?

5. Open the second branch valve when clean water without bubbles flows out of the return water purge valve. ?

6. Use the same method to open the remaining branch valves. ?

7. Finally, when opening the main return water valve, close the return water bleed valve to complete the operation. ?