Apparatus and instruments for heating, steaming, cooking, ventilating and water supply, particularly ovens (electric/gas), cooking ranges, stoves, cooking appliances (electric), cooking apparatus, hobs, hot plates, heater plates, oven interiors and cookers for domestic and commercial applications, microwave ovens, grills (electric/gas), fan-assisted cookers (electric), electric fryers, griddles, fast cooking appliances (electric), steam cookers (electric), electric bain-maries, electric warming cabinets for food, cooker hoods, extractors for use in kitchens