Termet Ecocondens Silver-25 PWM - Pressure does not decrease despite regulation

Hi

My grandmother recently switched to gas heating and a Termet ECOCONDENS SILVER-25 PWM stove was installed.
Grandma wanted to heat water, so the stove was turned on. The service technician or installer said that the pressure should be 1-1.5 bar, and if it was too high, unscrew the valve marked in the circle.
The pressure is 2.5 bar - I turn, turn, turn, and nothing drops, and after a long time it increases! That`s why I`m asking for advice if I`m doing it wrong or if there`s something wrong [it`s the first gas furnace in our immediate family, so we`re green in these matters].

Hello.
This is a valve for adding water to the system (increasing the pressure), not for releasing it, and this will not achieve the intended effect, but exactly the opposite.
On the right side of the photo you can see the magnetic filter. There is a valve at the bottom that allows you to release water and lower the pressure.

There`s a drain valve next to it.

Or release some water through the radiator vent to reduce the now too high pressure.

szyman12 wrote:

The service technician or installer said that the pressure should be 1-1.5 bar, and if it was too high, unscrew the valve marked in the circle.

It is assumed that the pressure in the boiler should be over 1.0 bar.
For example, in my boiler on a cold installation I have 1.4 bar. After heating the installation, the pressure increases by approximately 0.2 bar, i.e. to 1.6 bar.
In other words, during the 15 years of operation of the boiler, the pressure never spontaneously exceeded 2.0 bar.
If the pressure in the boiler increases automatically to 2.5 bar, something is wrong.
If it is a new boiler, the water filling valve may not be closed and water is seeping out, causing the pressure to increase.

Remember that the pressure in the boiler water system should be more or less constant and may change within the range of +-0.2 bar if the installation cools down or heats up.
With a fully operational boiler and efficient installation, there is no way for the pressure to rise above 2.0 bar.
Draining the water may be a temporary solution, but if the pressure keeps increasing and you have checked the water admittance valve to see that it is 100% closed, it requires the intervention of an installer/service technician.

Hello, do I need to unscrew this relief valve with a screwdriver or how?