I have moved into a house with a vaillant turbomax plus 824. The pressure when cold is very low (0.2). I have looked at the manuals, and it says the boiler needs refilling. However, the diagram in the installation manual on how to fill up the system looks nothing like mine! Is there suupposed to be a filling loop and key? I can't seem to find it. Any help will be very much appreciated!!! Also, is there supposed to be an automatic air release valve somwhere??!