While you wait for answers, we may have found some information which could help you.
Click here for Cast Iron Water
Low pressure below 1, Lockout on. won't rest?
Glen Dimplex Oil Filled Heater OFC2000 2KW?
vonhaur Dragan 2500w oil electric heater no power?
Fix my oil filled heater?
What size spanner to free rad bleed valve?
Oil filled radiator won’t stop clicking?