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HVAC · Australia

HVAC Symbols — Australia (AS 1668 / AS 3666)

Mechanical services drawings in Australia are read against AS 1668.2 for mechanical ventilation, AS 1668.1 for fire and smoke control, and AS/NZS 3666 for microbial control in air handling systems. The symbols themselves are the international ones, because a duct is a duct. What is different is how much fire and smoke control detail an Australian drawing carries, since AS 1668.1 puts smoke management on the same drawing set as the ventilation.

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AS 1668.2 / AS 1668.1 / AS/NZS 3666.112 symbols
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DuctworkControlsTerminalsEquipment

Ductwork

Supply Air Duct

Rectangular supply air ductwork

CIBSE Guide B

Extract Air Duct

Rectangular extract air ductwork

CIBSE Guide B

Circular Duct

Circular / spiral ductwork section

CIBSE Guide B

Controls

Volume Control Damper

Manual or motorised air volume control damper

CIBSE Guide B

Fire / Smoke Damper

Closes on alarm to maintain fire and smoke compartmentation under AS 1668.1

BS EN 15650 / CIBSE

Room Thermostat

Room temperature sensor / thermostat

CIBSE Guide H

Thermostatic Radiator Valve

TRV for individual radiator temperature control

CIBSE / BS EN 215

Terminals

Supply Air Grille

Wall or ceiling mounted supply air grille / diffuser

CIBSE Guide B

Extract Air Grille

Wall or ceiling mounted extract air grille

CIBSE Guide B

Equipment

Air Handling Unit (AHU)

Central air handling unit with filter, coil, and fan sections

CIBSE Guide B

Fan (Axial / Smoke Spill)

Axial fan. On an AS 1668.1 drawing this may be a smoke spill fan rated for high-temperature operation

CIBSE Guide B

Heat Exchanger

Plate or cross-flow heat exchanger / heat recovery unit

CIBSE Guide B

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Frequently asked questions about hvac symbols

What changed in the 2024 edition of AS 1668.2?
AS 1668.2 was updated in 2024, replacing the long-standing previous edition. It sets outdoor air rates, contaminant exhaust, and how those airflows are calculated and documented. If you are working from an older drawing set, check which edition it was designed against before assuming the airflow figures still comply.
Why do Australian mechanical drawings carry so much fire and smoke detail?
Because AS 1668.1 covers the use of ventilation and air conditioning for fire and smoke control, and it applies to the same ductwork the ventilation design uses. Smoke spill fans, fire dampers and their control wiring commonly appear on the mechanical services drawing rather than on a separate fire drawing.
What is AS/NZS 3666 and does it affect what I draw?
AS/NZS 3666 covers microbial control in air handling and water systems, including cooling towers. It mostly affects access and maintainability: plant has to be reachable for inspection and cleaning, so access panels and clearances belong on the drawing rather than being resolved on site.
Are these symbols the same as UK or US ones?
Largely, yes. Ducts, dampers, grilles, fans and air handling units are drawn the same way across all three. The differences are in the standards named in the title block and in the fire and smoke control content described above.

Related symbol guides

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HVAC & Ventilation Symbols — UK (CIBSE)

12 symbols · CIBSE Guide B / BS EN 15232 / BS EN 16798

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HVAC Symbols — US (ASHRAE / ANSI)

12 symbols · ASHRAE / ANSI/ASME / IMC (International Mechanical Code)

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Electrical Symbols — Australia (AS/NZS 3000)

23 symbols · AS/NZS 3000:2018 / IEC 60617

Related certificates on CertBox

Au Certificate Of Compliance Non Prescribed

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Symbols based on AS 1668.2 / AS 1668.1 / AS/NZS 3666.1. This is a reference guide only — always consult the full standard for official symbol definitions.