air conditioners and installations; space heating and/or cooling units and installations; central heating units and installations, heat recovery units; heat pumps, heat accumulators, heat exchangers, central heating water radiators; electrical heating elements; electric heaters featuring fans; under floor heating units; humidifiers; dehumidifiers; refrigerators; chill cabinets for stocking and displaying of food and and drink at retail outlets; beer coolers used for installation between a keg of beer and a beer tap for cooling beer immediately before it is dispensed; die coolers for cooling moulding dies during a manufacturing process; cold ceiling units in the nature of units for inclusion in a ceiling and provided with water channels through which cold water may be pumped to cool a room, and structural parts and fittings for the foregoing