alpha cb24 filling loop

[LondonFlat28]

I've read a couple postings on the topic of re-pressurizing the Alpha CB24 boiler when the pressure gauge falls below the .75 bar (outside the green field on the gauge) and understand the process of manually refilling the boiler via the filling loop, however the filling loop that is attached to the unit in my flat (which I did not install) does nothing, leaving me confused.

The filling loop attached to my Alpha CB24 is a "metal braded flexible hose", as described on Alpha's Control Panel Troubleshooter page, with a single black handled tap on the started end, but when I open the tap 1/4 or even full I get no response. I've attached photos of the filling loop on Album ...

//www.diynot.com/network/LondonFlat28/albums/

My question is, am I missing a second tap (there is a flat-head screw right next to the black handled tap on the loop)? what's the next step if the filling loop fails to fill the tank to the boiler?

appreciate the help, Dan

 

[Garfeild]

Follow the loop to the other end there should be another tap with just a "flat headed screw"on it,open this slowly with a nicely fitting screwdriver while the black hadled tap is open,you should hear water flowing through.