Hierarchy classification:

1. top of the aat hierarchies
2. Objects Facet
3. Object Groupings and Systems (hierarchy name)
4. systems (equipment)

Narrower term/s

• waterworks
• electrical systems[+]
  • emergency power supply
  • grounded systems
  • electrical system components [NP] [+]
    • actuators
    • oscillators
    • transistors
    • electron tubes [+]
      • diodes [+]
      • vacuum tubes [+]
    • capacitors
    • electrodes [+]
      • ion-selective electrodes
    • insulators
    • resistors
    • rheostats [+]
      • potentiometers [NP]
    • rheotomes
    • raceways [+]
      • busways
    • electric cables [+]
      • armored cables
      • power cables
    • circuit breakers
    • circuits
    • electric conduits
    • switchboards
    • electric switches
    • electric wiring
    • ground-fault circuit interruptors
    • power outlets
    • panelboards
    • receptacles
    • transformers [+]
      • step-down transformers
      • step-up transformers
      • Tesla coils
    • circuit boards
    • occupancy sensors
    • photovoltaic cells [+]
      • solar cells
    • punch blocks (electrical connections)
    • magnetrons
    • [temporary alphabetical list: electrical system components] [+]
      • alligator clips
      • anodes
      • ballast tubes
      • battery adapters
      • battery charger adapters
      • battery jars
      • battery testers
      • cable fault locators
      • AC-DC converters
      • binding posts
      • cathodes
      • decade boxes
      • dimmer switches
      • electric wires
      • electrical adapters
      • electrical boxes
      • electrical chokes
      • [electrical maintenance & repair equipment]
      • electrical modulators
      • electrical outlets
      • electrical plugs
      • electrical shunts
      • electrical switches
      • electrical terminals
      • electrical testers
      • electrical tubes
      • electrician's pliers
      • electrolytic capacitors
      • extension cords
      • fuse blocks
      • fuse boxes
      • fuse pullers
      • impedance transformers
      • induction coils
      • growlers
      • junction boxes
      • knife switches
      • magneto and coil testers
      • outlet boxes
      • relays
      • resistance boxes
      • resonant transformers
      • plug adapters
      • power cords
      • receptacle plugs
      • transfer switches
      • tube sockets
      • utility boxes
      • variable capacitors
      • voltage multipliers
      • single side band modulators
      • socket covers
      • socket plugs
      • wire nuts
      • wire sorters
      • solenoids
      • solenoid switches
      • spark arresters
      • time switches
• conveying systems[+]
  • vertical conveying systems [+]
    • dumbwaiters (conveying systems)
    • elevators [+]
      • [elevators by form] [+]
      • [elevators by function] [+]
      • [elevators by mode of operation] [+]
    • manlifts
    • platform lifts
  • [diagonal and multidirectional conveying systems] [+]
    • inclined elevators
    • escalators
    • inclined lifts [+]
      • stair lifts
      • inclined wheelchair lifts
    • moving ramps
    • pneumatic tubes
  • horizontal conveying systems [+]
    • moving walkways
• HVAC[+]
  • heating systems [+]
    • furnaces (heating components) [NP] [+]
      • warm air furnaces [+]
    • resistance heating
    • hot water heating
    • radiant heating [+]
      • panel heating
      • heat exchangers [NP] [+]
    • solar heating (systems) [+]
      • active solar heating
      • passive solar heating
    • steam heating [+]
      • vacuum heating
    • warm air heating [+]
      • hypocausts
      • forced air heating
      • gravity heating
      • kangs (heating system)
      • ondols
    • heat-distributing units [NP] [+]
      • baseboard units
      • convectors
      • radiators
      • thermal masses
  • ventilation (systems) [+]
    • exhaust ventilation (systems)
    • mechanical ventilation (systems)
    • natural ventilation (systems)
    • ventilation system components [NP] [+]
      • ventilators (ventilation components)
      • air filters [+]
      • air-handling units
      • blowers
      • dampers (HVAC components)
      • air distribution systems
      • air diffusers
      • air ducts
      • registers (HVAC components)
      • cowls (ventilation system components)
      • plenum chambers
      • fume hoods
  • air conditioning [+]
    • central air conditioning
    • incremental air conditioning
    • air washers [NP]
  • air cooling [+]
    • chilled water systems
    • refrigerant systems
    • ice storage systems
    • passive cooling
  • HVAC components [NP] [+]
    • ventilation system components [+]
      • ventilators (ventilation components)
      • air filters [+]
      • air-handling units
      • blowers
      • dampers (HVAC components)
      • air distribution systems
      • air diffusers
      • air ducts
      • registers (HVAC components)
      • cowls (ventilation system components)
      • plenum chambers
      • fume hoods
    • [cooling, heating and humidifying components] [+]
      • furnaces (heating components) [+]
      • air washers
      • boilers (HVAC components) [+]
      • cooling towers
      • heat pumps [+]
      • heat exchangers [+]
      • thermostats
      • radiator enclosures
      • breechings
      • trompes (cooling components)
      • solar thermal panels
      • stovepipes (pipes)
    • heat-distributing units [+]
      • baseboard units
      • convectors
      • radiators
      • thermal masses
  • [temporary alphabetical list: HVAC] [+]
    • chiller systems
    • coal furnaces
    • dehumidifiers
    • environmental control elements
    • exhaust fans
    • fireboards
    • fireplace dampers
    • fireplace doors
    • hvac boilers
    • hvac coils
    • hvac compressors
    • hvac condensers
    • hvac evaporators
    • hvac filters
    • recirculating fans
    • vent caps
    • ventilation fans
    • ventilator damper
• lighting[+]
  • [lighting by method of illumination] [+]
    • electric lighting
    • gas-lighting
    • fluorescent lighting
    • daylighting
    • artificial lighting
  • [lighting by location or context] [+]
    • exterior lighting
    • interior lighting [+]
      • cornice lighting
      • cove lighting
      • valance lighting
    • stage lighting
  • [lighting by function] [+]
    • architectural lighting [+]
      • decorative lighting
      • outline lighting
    • emergency lighting
• stormwater systems
• communication systems (mechanical and electrical systems)[+]
  • television antenna systems
  • clock and program systems
  • sound systems [+]
    • intercom systems
    • public address systems
    • doorbells [+]
      • door chimes
    • sound-reproducing systems
    • audioguides
    • call bells
  • NTSC system
• protection systems[+]
  • fire protection systems [+]
    • fire alarm systems [+]
      • auxiliary fire alarm systems
      • local fire alarm systems
      • proprietary fire alarm systems
      • remote-station fire alarm systems
      • fire alarm system components [NP] [+]
    • fire extinguishing systems [+]
      • fire extinguishing system components [NP] [+]
  • security systems [+]
    • electronic security systems
    • security system components [NP] [+]
      • burglar alarms
  • protection system components [NP] [+]
    • fire alarm system components [+]
      • fire detectors [+]
      • smoke detectors [+]
      • manual stations
    • fire extinguishing system components [+]
      • fire sprinklers
    • security system components [+]
      • burglar alarms
    • [temporary alphabetical list: protection system components] [+]
      • alarms
      • gas alarms
      • gas detectors
      • gas mask carriers
      • fire alarm boxes
      • fire protection devices [+]
      • protective devices
      • security card readers
      • security devices
      • security keypads
      • security locks
      • security scanners
      • smoke alarms
      • x-ray security scanners
      • sandbags
• plumbing systems[+]
  • [plumbing and stormwater system components] [NP] [+]
    • leader heads
    • catch basins
    • cesspools
    • cisterns (plumbing components)
    • drains [+]
      • area drains
      • fixture drains
      • storm drains
      • French drains
    • gutters (building drainage components) [+]
      • arris gutters
      • valley gutters
      • back gutters
      • eaves gutters
    • piping (plumbing system components) [+]
      • downspouts
      • drainage piping
      • DWV piping
      • mains (plumbing)
      • stacks (piping) [+]
      • risers (piping)
      • service pipes
      • pipe fittings (components)
    • plumbing fixtures [+]
      • drinking fountains
      • washfountains
      • bathtubs [+]
      • bidets (plumbing fixtures)
      • sinks (fixtures) [+]
      • toilets (fixtures) [+]
      • urinals (plumbing fixtures)
      • laundry trays
      • water conditioners
      • shower heads
      • bath basins
    • seepage pits
    • septic tanks
    • sumps
    • traps (plumbing system components) [+]
      • fixture traps
      • house traps
    • water heaters [+]
      • solar water heaters
    • water storage tanks
    • leaching fields
    • impluvia
    • waterspouts [+]
      • gargoyles
      • lion-head spouts
      • śuṇḍu
    • safes (plumbing components)
    • rain barrels
    • [temporary alphabetical list: plumbing and stormwater system components] [+]
      • bathroom sinks
      • drain covers
      • indoor fountains
      • kitchen sinks
      • pedestal sinks
      • plumbing & drainage elements
      • plumbing pipes
      • plumbing pumps
      • sink sprayers
      • sink stoppers
      • water heater stands
      • water supply pipes
    • nāla
  • water distribution systems [+]
    • downfeed systems
    • upfeed systems
  • sanitary drainage systems
• infrastructural systems[+]
  • transit systems (infrastructure) [+]
    • railroads (infrastructure)
    • public transit (infrastructure) [+]
      • [public transit by form] [+]
      • [public transit by location or context] [+]
  • utilities (infrastructures) [+]
    • water supply systems [+]
      • irrigation systems
      • water storage systems
    • municipal lighting
    • street lighting
    • utilities components [NP] [+]
      • water mains
      • utility poles [+]
      • power lines
      • gas pipelines
      • oil pipelines [+]
      • oil pumping stations
  • telecommunication systems [+]
    • police communication systems
    • telephone systems [+]
      • telephony
    • telecommunication systems components [NP] [+]
      • television receivers
      • radio receivers
      • telephones [+]
      • transceivers [+]
      • antennas [+]
      • field telephones
      • telephone wires
      • microphones [NP] [+]
      • telegraphs [+]
      • liquid crystal displays
      • remote controls
      • [temporary alphabetical list: telecommunication systems components] [+]
      • fax machines
      • electronic filters
      • televisions (viewing devices)
    • television (telecommunication system) [+]
      • cable television
      • high-definition television
    • radio (telecommunication system) [+]
      • shortwave radio
    • intranets
    • wireless sensor networks
    • telex
  • drainage systems
  • Internet [+]
    • World Wide Web [+]
      • Web sites
      • Semantic Web
• signage
• seating[+]
  • icpalli (seat)
• geographic systems[+]
  • geographic information systems
  • Global Positioning System
  • Electron Marker System
• film projection systems[+]
  • VistaVision (TM)
• computer systems[+]
  • information systems [+]
    • cataloging systems
    • collection management systems
• digital projection