How do you add water to radiators? - Bake de dietrich which valve unscrew?

Please help. I am a layman and this is my first day in a new home. On the stove switched on or off, the pressure dropped below 1. De Dietrich MCR3. I enclose the pictures of the valves:

At the wall you have two valves connected by a hose.

And which I have to unscrew, because one is probably letting water down. When the stove is switched on or off?

With the boiler switched off. Better photos. To get the water you need to unscrew both.

[url=https://obrazki.elektroda.pl/7246778200_1485338476.jpg] [Img]
So those that come out of the wall? I have to wait some time after switching off the boiler?

It does not open to me and I do not see these valves. Open those that are connected by a hose.

So that you would not be "Total layman" as you wrote, download the manual from the net, from which you will learn many things about the boiler.
To top up the water of the closed CO circuit unscrew the valve at the end of the hose connecting the third and fourth corrugated wires counting from the left in your photo. Before refilling, the boiler should be cold and preferably turned off to avoid thermal shock.
After filling the water in the circuit (1.5-2bar), close the valve by adjusting its knob perpendicular to the valve.
You start the boiler and it will vent for about 4 minutes before it fully starts according to instructions.
If you do not want to overpay for gas, I advise you to read the manual or call a service technician. Greetings.

Just remember that the two valves from the filling should be turned off later, so that the water from the water supply will not blow to CO, because it will pour out with the safety valve

Recently, I had two such cases with clients - neighbors, one day one, and the other on the second day. I thought I was in a "hidden camera" or in the "Fault" program

Thank you for your help. Normal pressure, radiators vented and heated. As for the filling valves, I understand that they are supposed to be in position as per picture 1? Parallel to the serpentine? Because if this is the case, I can pour this water with a small valve and now I do not know how it is correctly. The instructions just got this week so I will probably read. greetings

Handle along the valve = open
Handle crosswise = closed

Buddy @daydeamer as you wrote in your post # 9 "this little valve" is used to top up the water in a closed circuit and after completing it, you close it as colleague @ tomek3108 wrote. However, the larger remaining ones "entering the wall are: 2 from the central heating circuit and 2 from the hot utility water CWU that is to be washed in. The central heating system is closed and its complement is completed. connected this hose with a valve to be completed.

I have the same problem, I don't know which valve it is, help.