Mechanical and electronic calculators and computational devices

Apparatus for heating, cooling, ventilating, air conditioning, and installations thereof; air driers, air re-heaters, sterilisers, gas burners, central heating radiators, chimney flues, drying apparatus, desiccating apparatus, cooking apparatus, and installations thereof; ovens, stoves, and fittings therefor; refrigerators and refrigerating equipment, and installations thereof; air filtration apparatus and installations; evaporative air coolers, fans, blowers, filters, ducts, controllers, fittings and accessories therefor; ventilation equipment including ventilation hoods