THE RADIATOR VALVE IS OPEN, THERE IS NO AIR IN IT AS I BLED IT, NO THERMOSTAT AND IT WORKED UNTIL ABOUT A MONTH AGO. THE WHOLE SYSTEM WAS FLUSHED OUT AND AN INHIBITER PUT IN ABOUT 18 MONTH AGO AND MAYBE IT HASN'T BEEN ON FULL HEAT SINCE THEN. WHAT DO YOU THINK?