increasing pressure in Vaillant ecoTEC plus 637

[vaillant ecoTec]

hi, my pressure indicator on the manometer is near to 0 (hardly touches the dark grey area).
How could I increase the pressure in the system, please?

 

[grahamgas]

Hi
You should have a silver braided hose close to or near your boiler.At the end of this hose, should be a valve.You need to open this valve to allow water into your system, thus increasing the pressure on your gauge.
Increase pressure to about 1.5, or ten o clock as you look at the gauge.

Graham