Piping Purification Water 3 Air conditioning 2 Air-compressors 2 Bearings (Machinery) 2 Combustion 2 more ... Condensers (Steam) 2 Design and construction 2 Drainage 2 Heat 2 Plumbing 2 Power-plants 2 Pumping machinery 2 Steam engineering 2 Transmission 2 Water-supply engineering 2 Actuators 1 Animal housing 1 Ash disposal 1 Automatic control 1 Belts and belting 1 Boilers 1 Brakes 1 Cleaning 1 Clutches (Machinery) 1 Combined cycle power plants 1 Compressed natural gas 1 Condensers (Vapors and gases) 1 Cooling towers 1 less ...