I have a very old worester 28si and the pressure is down to around 0.4 i cannot figure out how to up the pressure. The external filling hose doesnt seem to fit or do anything as it has one valve that i can turn halfway and the other one hasnt got a flathead screw fitting. There doesnt seem to be a internal filling kry eithet and im confused. Its in a little cupboard upstairs and underneath there is two connectors right next to it with another pipe running to a closed loop with a cap. There is a black turn valve on top of one that doesnt work either any suggestions. Just started livig on my own and this isnt my kind of area.

Elliott, March 2018

These may help

https://www.worcester-bosch.ie/professional/support/literature/worcester-si-ii-installation-instructions

and

https://www.manualslib.com/manual/836842/Worcester-28si.html

You may be able to find more advice on a plumbers forum (g search)

You can search for more, March 2018