Upstairs radiators are a bit colder than they ought to be, I'm guessing they need bleeding... I'm completely ignorant of the subject, so stupid questions coming up:
a) Do you need to do each radiator separately? (I assume you do)
b) How do I bleed this radiator:
Just undo the screw a bit with the heating off, or is there some dark art to radiator manipulation I'm not aware of? There's a little bit under the screw that sticks out, what's that for?