Air conditioning apparatus; Air purification units; Air-conditioning, air cooling and ventilation apparatus and instruments; Dripper irrigation systems, comprised of valves, filters and regulators; Extractor hoods for kitchens; Filters for drinking water; Gas burners; Gas water heaters; Heating installations; Hot plates; Humidifiers; Interior environment control system for commercial buildings, namely, heaters, ventilators and humidifiers all sold as a unit; Sewage treatment plants; Solar water heaters; Waste water purification apparatus, installations and tanks; Water heaters; Water purification installations; Water purification machines; Water purification, sedimentation and filtration apparatus for clarification, thickening and filtration of water, waste water and industrial water