no pressure in CH system

[bedworthkid]

Trying to help my daughter from a distance. Central heating system has zero pressure but there's no obvious tap on the boiler to add more water. There is a 90 degree connector with square head with cross head screw and 90 degree marks, does anyone know what this is?
Thanks for any advice.

 

[footprints]

That's the gas valve.

 

[CWHEATING]

Gas pipes not sleeved. Whoops.

 

[CWHEATING]

Sometimes filling loops are not actually by the boiler. If it’s a heat only boiler it’s possible to add a pressure kit to pressurise it. This consists of a filling loop pressure gauge and expansion vessel that’s most likely red. Check other cupboards for a red exp vessel.