Domestic central heating appliances; Domestic heating appliances; Air heaters; Boilers being parts of central heating installations; Boilers for central heating installations; Boilers for hot water supply installations; Boilers for use in heating systems; Central heating boilers; Circulators (water heaters); Continuous flow work heaters; Diesel fuel line heaters; Domestic boilers; Flues for heating boilers; Forced air type space heaters; Gas boilers; Gas boilers (other than parts of machines); Gas boilers for central heating; Gas boilers for the heating of swimming pools; Gas boilers for water heating; Gas fired boilers; Gas fired boilers for producing domestic hot water; Gas fired heaters; Gas fired space heaters; Gas fired water heaters; Gas space heaters; Heaters; Heaters for bath water; Heaters for baths; Heaters for heating irons; Heaters for shower baths; Heaters for sink water; Heaters for wash basin water; Heating boilers; Hot water boilers; Hot water heaters; Hot water supply heaters; Immersion heaters; Industrial heaters; Installations combining boilers and steam generators for heating; Installations combining boilers and steam generators for producing hot water; Pressure relief apparatus for use with water heaters; Propane gas fired space heaters; Room heaters; Sauna heaters; Space heaters; Space heaters for rooms; Steam boilers (other than parts of machines); Steam boilers for steam generating (other than parts of machines); Swimming pool heaters; Water boilers; Water heaters; Water heaters (apparatus); Water heaters for shower baths; Water heaters for showers; Water immersion heaters