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Book - School of Science and Technology

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682 Running costsTable 23.14 Economic life <strong>of</strong> equipmentType Item Life (years)Boiler plantSteam <strong>and</strong> HTHWshell <strong>and</strong> tube 20±25water tube 25±30electrode 15±20Medium <strong>and</strong> LPHWsteel 15±20cast iron sectional 15±25electrode 15±20Incinerators 15±20Boiler auxiliaries Combustion controls 15±20Condensing 10±20Boiler electrodes 5±10Feed pumps/Feed water treatment 15±20Oil burner 15±20Atmospheric gas burner 20±25Forced air gas burner 15±20Solid fuel h<strong>and</strong>ling 10±15Fans 15±20Instrumentation 10±20Chimney Stainless steel 15±25Heating equipment Heat exchangers 20±25Radiators, cast iron 20±25Radiators, steel 15±20Ceiling heating 20±30Unit heaters, gas or electric 10±15Unit heaters, hot water or steam 15±20Fan convectors 12±18Liquid distribution Pipework 25±30Pumps, base mounted 20±25Pumps, pipeline 15±20Pumps, sump 8±12Pumps, condensate 10±15Tanks 10±15Valves 20±25Flexible hoses, connections 8±15Refrigeration plant Reciprocating, large 15±20Reciprocating, medium or small 10±15Centrifugal 15±20Absorption 15±20DX split cooling units 10±15Cooling towers, depending on material 10±25Air-cooled condensers 15±20Evaporative condenser 15±20Heat pumps 10±15Air-h<strong>and</strong>ling plant Package units, external 10±15Package units, internal 15±20Cooling coils/heating coils 15±20Humidifiers 10±15Fans, centrifugal (heavy duty) 20±25Fans, axial 15±20Air distribution Ductwork 25±30Dampers 15±20Fans, propellor 10±15

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