nether mind air in system.... its as earlier, sludge in system, this causes the TRV too stick or no flow throw the TRV too lockhield. .............
close both down and drain and remove rad, flush rad with hose pipe and replace, open valves, lockshield same number of turns it took to close, check system pressure at boiler and increase to a little above 1bar (1.2/1.4). run heating this should be ok.
system may need a full flush dead easy, if in doubt post again..
CLFGAS
clfgas
February 2007