Hot water systems and installations; solar hot water systems and installations; apparatus for heating water; electric water heaters and parts therefor in this class; gas water heaters and parts therefor in this class; apparatus for heating water using solar energy; parts and accessories in this class for hot water systems and installations, including solar hot water systems; regulating and safety accessories for water apparatus and gas apparatus; safety accessories for water or gas apparatus and pipes; solar collectors for heating; solar collectors for heating water; solar collectors for heating including evacuated collector tubes