While you wait for answers, we may have found some information which could help you.
Click here for System Valve RadsFix my oil filled heater?
Low pressure below 1, Lockout on. won't rest?
What size spanner to free rad bleed valve?
Oil filled radiator won’t stop clicking?
How can I mend my Hyundai oil filled radiator?
Where can I get a manual for my ritetemp oil heater ?