Boiler pressure

[RhubarbAndMustard]

Can anyone help please? We have a Valliant boiler and the pressure is below zero. This happened before and the boiler engineer said to turn 2 screws (1 at a time) to add in the pressure...but I can only find one turnable screw. Internet said it should be either end of a grey flexible pipe, but of course our boiler has no grey flexible pipes! Any ideas anyone?

I would be eternally grateful as I'm on Mat leave and could really do without the bill of an engineer!

The turnable screw I can find is at the bottom of the silver pipe.

Is there not one on the opposite side? Ours are opposite each other?

If you unscrew it all the day, do you hear a whooosh sound?

Ours drops below zero as we have a leak, you might also want to check it's not leaking anywhere?

I have a water pipe that I connect then open the value to let the water in to heighten the pressure..

To be on complete zero seems to be a bit of a concern. I agree with another poster that check for leaks

We found it and there was a woosh sound. Problem fixed. Thank you! I will definitely keep an eye on it in case of a leak.