4D Valve Control Issue: Jumping Return Temp in Ogniwo Eko Plus M Boiler with Afriso Actuator

Hello,

Currently I have a problem with the setting of the 4D valve. Boiler Ogniwo Eko plus M, valve 4D Afriso 1 1/4 "with an actuator, which performs the return protection function via the controller (a sensor at the return end at the boiler). So far, there is no sensor behind the supply valve. The problem is the cyclical opening and closing of the valve and jumps return temperature, which can be seen exactly in the graphs, and the return often drops well below the minimum set value by the controller.
In the boiler manual I read that the boiler cycle between the valve and the boiler to perform the return protection function must be done on a gravity cycle, if not an additional pump.

Can you explain what this circuit is all about and did Fachman put it together well because I have the impression that not ...?

Charts how it opens / closes, etc.: https://esterownik.pl/device/15172

The diameter of the pipes in the boiler circuit is too small. Either increase the cross-section or add a boiler pump between valve 4d and the boiler return.

The diameter of the pipes in the boiler circuit is 1 inch. The spigots from the boiler and the valve are 1 1/4 inch from what I could see. I understand that the pipes should also be at least 1 1/4 inch in this circuit?
Can someone explain in plain language what the gravity circulation in the boiler cycle is for or an additional pump if there is already a CH pump?

In order to heat the return to the boiler so that there is no condensation. In other words, that the boiler does not sweat and it works for a few years.

I don't mean what the return protection is supposed to do, but why the boiler cycle between the boiler and the 4d valve must be carried out by gravity or with an additional pump if there is the main CH pump which "pushes" the entire installation?

Because the main CH pump rotates the water only in the radiator circuit. If the water flow in the boiler circuit is too low, all the water goes to the installation without separating and heating the return.

Okay, now I understand . The question is whether a small 5W circulation pump on the return of the boiler circuit is enough?

It is not enough, and the trail will hit her faster.

Could someone give the parameters that the pump should have for such a boiler cycle?