hi all,recently bled upstairs radiator didnt put back on 4 about 2 months.fired up boiler only one bedroom radiator worked,so ive just bled whole system,but 3 downstairs radiators still full? im not very good as u can see,any help.bioler is a barlo balmoral 45f,dont think its a sealed system ?header tank in loft etc,bleed screws at side of all rads.