Repair Systems — 07
Mechanical Exhaust Fans
Technical product reference for inline duct fans, ceiling-mounted exhaust fans, wall-mounted exhaust fans and acoustic attenuation duct systems for mechanical exhaust fan replacement and upgrade in Australian Class 2 strata apartment buildings.
What are mechanical exhaust fan systems?
Mechanical exhaust fans in Class 2 strata apartment buildings fail for several reasons: motor burnout from age or continuous running, bearing failure causing noise and reduced airflow, duct blockage from lint, dust and debris accumulation, and inadequate airflow for the actual duct run length — where a fan specified for a short run is installed on a long run to a common exhaust riser, resulting in insufficient extraction. These failures lead to excess moisture, condensation, mould growth, and non-compliance with AS 1668.2 ventilation requirements.
Fan type selection is critical to performance. Inline fans and centrifugal ceiling fans are suitable for longer duct runs because they develop higher static pressure than axial fans, allowing them to overcome duct friction over longer runs. Axial wall-mounted fans are suitable for direct-to-wall exhaust only. Installing an axial fan on a long ducted run to a remote riser is a common cause of inadequate airflow — the fan type must be matched to the duct run length and static pressure of the installed system.
Acoustic duct is used to manage noise transmission in exhaust systems where the duct run passes through or adjacent to shared walls, bedroom walls, and ceiling plenums in strata buildings. Standard flexible duct transmits exhaust fan motor noise and airborne sound from adjacent apartments — internally lined acoustic duct with mineral wool or foam lining attenuates this noise and is specified as part of an exhaust fan replacement or upgrade where noise complaints are part of the defect history.
Do not confuse with:
- Passive mushroom vents — passive roof space ventilation units driven by wind pressure and thermal buoyancy — not powered exhaust systems
- Carpark ventilation fans — high-volume industrial fans for carpark CO and smoke extraction — not residential bathroom or kitchen exhaust
- Window exhaust fans — window-mounted units installed in a window opening — not in-ceiling or in-duct exhaust systems
Product Reference
4 products — 3 brands — mechanical exhaust fan systems — scroll to view all
Fantech 150mm Inline Duct Fan
150mm inline centrifugal duct fan — kitchen and bathroom exhaust
System Description
TODO: owner confirm model name — A 150mm inline duct fan designed for kitchen range hood exhaust and bathroom exhaust systems in residential and multi-unit buildings where duct runs are long or have multiple bends that generate significant static pressure. Inline fans are installed within the duct run — typically in the ceiling plenum or plant room — rather than at the ceiling or wall face. This placement allows the fan to draw air through the full duct run length, making it suitable for strata apartment bathroom and kitchen exhaust systems where the common exhaust riser may be several floors away from the apartment. Confirm duct diameter, external static pressure, and required airflow against AS 1668.2 requirements before specifying. Confirm current product model name with Fantech Australia. An accessible maintenance point or access panel must be provided in the ceiling or duct run adjacent to the installed fan.
Technical Properties
- 150mm duct connection — centrifugal impeller — suits long duct runs with higher external static pressure than axial fans can overcome
- Inline installation within duct run — fan is not visible at the ceiling or wall face — suitable for kitchen range hood and bathroom exhaust in strata apartments
- Centrifugal fan type — higher static pressure capability than axial fans — suitable for duct runs with multiple bends and risers
Limitations
- Inline installation requires access for maintenance — an access panel in the ceiling or adjacent duct run is mandatory
- Centrifugal fans are larger and heavier than axial fans — confirm structural support and space available in the ceiling plenum before specifying
- Not suitable for direct wall or ceiling face exhaust without ductwork — inline fan must be connected to a full duct system
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Manrose CF100 Ceiling Exhaust Fan
100mm ceiling-mounted centrifugal exhaust fan for bathrooms
System Description
The Manrose CF100 is a 100mm centrifugal ceiling-mounted exhaust fan for bathroom and toilet exhaust in residential and multi-unit buildings. The centrifugal design allows it to move air over longer duct runs than axial fans, providing maximum performance even against pressures from long duct lengths and resistance by grilles. The fan is installed in the ceiling face, visible from below, and connects to a 100mm flexible or rigid duct run in the ceiling plenum. Extract rate is 90 m³/hr (25 L/s). The CF100 includes an integral backdraft shutter (spring-operated non-return flap) to prevent reverse airflow and odour migration from the common exhaust duct when the fan is not running — essential in strata apartment buildings with common exhaust risers. The CF100T variant includes an adjustable overrun timer that keeps the fan running for a set period after the light is switched off — improving moisture extraction in bathrooms and reducing condensation on surfaces. Noise level is 42 dB(A) at 3m. Confirm the selected CF100 variant (standard, timer, humidity) against the project requirements.
Technical Properties
- 100mm centrifugal ceiling-mounted fan — 90 m³/hr (25 L/s) extract rate — installs in standard ceiling opening — visible from below in bathroom or toilet
- Integral backdraft shutter (spring-operated non-return flap) — prevents reverse airflow through the exhaust duct when fan is off — essential in strata common exhaust riser systems
- Adjustable overrun timer (CF100T variant) — fan continues to run after light is switched off — improves moisture extraction and reduces condensation
Limitations
- Centrifugal fan — designed to move air over longer duct runs than axial fans, but still confirm duct run length and static pressure against Manrose CF100 performance data before specifying
- 100mm duct diameter — confirm existing duct diameter before specifying — reducing duct diameter from an existing larger duct will increase static pressure and reduce airflow
- Ceiling-mounted — installation requires cutting or enlarging an opening in the ceiling — confirm ceiling type and structural framing before proceeding
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
System Description
TODO: owner confirm model name — A Clipsal Airflow wall-mounted exhaust fan with an integral backdraft shutter for direct wall exhaust in bathrooms, toilets, and laundries where the external wall allows direct exhaust without ductwork. Wall-mounted exhaust fans are installed through an external wall opening and exhaust directly to the outside — eliminating the duct run and static pressure limitations of ceiling fans connected to a common exhaust riser. This makes wall-mounted fans suitable where the bathroom or toilet has direct access to an external wall. In Class 2 strata apartment buildings, wall-mounted exhaust fans are less common than ceiling fans — most apartments do not have a bathroom with direct access to an external wall. However, in ground-floor units, corner units, or where the bathroom abuts an external wall, a wall-mounted fan is an effective and simple solution. The integral backdraft shutter prevents reverse airflow and wind-driven rain ingress when the fan is not operating. Confirm current model name and specifications with Clipsal before specifying.
Technical Properties
- Wall-mounted axial exhaust — installs through external wall — no ductwork required — direct exhaust to outside
- Integral backdraft shutter — prevents reverse airflow and wind ingress when fan is not operating
- 100mm nominal diameter — confirm wall thickness and construction type before specifying — core drilling required through masonry or concrete walls
Limitations
- Requires direct access to an external wall — not suitable for internal bathrooms or bathrooms remote from an external wall
- Wall penetration through concrete or masonry requires core drilling — confirm wall construction and structural implications before proceeding
- Axial fan — limited static pressure — not suitable for ducted installations or long runs — direct wall exhaust only
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Fantech Acoustic Attenuation Duct
Lined flexible acoustic duct for exhaust noise reduction
System Description
Fantech acoustic attenuation duct is an internally lined flexible duct used in exhaust fan systems to reduce airborne noise transmission through duct runs that pass through shared walls, ceiling plenums, and floor-ceiling assemblies in strata apartment buildings. Standard flexible duct transmits exhaust fan motor noise and airborne sound from adjacent apartments through the duct walls — acoustic duct with internal mineral wool or foam lining significantly attenuates this noise. Acoustic duct is typically installed between the exhaust fan and the main duct riser, or throughout the entire duct run in noise-sensitive applications. In Class 2 strata apartment buildings, exhaust fan noise transmitted through shared duct systems is a common complaint — particularly in bathroom exhaust systems where the duct passes through or adjacent to bedroom walls or ceiling spaces. Specifying acoustic duct as part of an exhaust fan replacement or upgrade addresses both the airflow compliance requirement (AS 1668.2) and the acoustic comfort requirement. Confirm duct diameter and acoustic performance rating with Fantech before specifying.
Technical Properties
- Internally lined flexible duct — mineral wool or foam acoustic lining — attenuates airborne fan noise transmitted through duct walls
- Available in standard exhaust duct diameters — confirm required diameter (100mm or 150mm) with current Fantech range
- Flexible construction — allows routing around obstructions in ceiling plenums without sharp bends that increase static pressure
Limitations
- Acoustic duct has a higher flow resistance than standard flexible duct — confirm static pressure implications against the selected fan performance curve before specifying
- Flexible duct — must not be kinked, compressed, or installed with unsupported sags — straight runs with gradual bends required for correct airflow and acoustic performance
- Acoustic lining must remain dry — condensation within the duct can saturate lining and reduce acoustic performance — confirm vapour barrier and insulation requirements
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
System Comparison
Side-by-side technical comparison of mechanical exhaust fan products. Confirm current product specifications with manufacturer TDS.
| Product | Brand | Type | Diameter | Max pressure | Duct required | Primary use |
|---|---|---|---|---|---|---|
| TODO: confirm — Fantech 150mm inline fan (model TBC) | Fantech | Inline (confirm type with TDS) | 150mm | High (confirm TDS) | Yes — inline duct install | Kitchen / bathroom — long duct runs |
| Manrose CF100 | Manrose | Ceiling centrifugal | 100mm | Medium-high — 90 m³/hr (25 L/s) | Yes — ceiling duct to riser | Bathroom / toilet ceiling exhaust |
| TODO: confirm — Clipsal Airflow wall fan (model TBC) | Clipsal | Wall-mounted axial | 100mm | Low (direct wall) | No — direct wall exhaust | Bathroom / toilet — external wall |
| Fantech Acoustic Duct | Fantech | Acoustic attenuation duct | 100mm / 150mm | N/A — duct component | N/A — is the duct | Noise reduction in exhaust duct runs |
Brand Equivalents
Mechanical exhaust fan equivalents across brands active in Australian Class 2 strata remediation.
| System type | Fantech | Manrose | Clipsal |
|---|---|---|---|
| Inline duct fan (150mm) | TODO: confirm model name | — | — |
| Ceiling centrifugal exhaust fan | — | CF100 | — |
| Wall-mounted exhaust fan | — | — | TODO: confirm model name |
| Acoustic attenuation duct | Acoustic Duct | — | — |
Airflow design and electrical compliance
- Exhaust fan airflow must comply with AS 1668.2 — minimum 25 L/s for bathrooms and toilets — airflow compliance must be confirmed by a mechanical engineer before specifying a replacement fan
- Fan installation requires a licensed electrician — hardwired exhaust fans are not DIY installations — confirm switching, timer, and circuit requirements with the electrical contractor before proceeding
- Inline fans must be accessible for maintenance — provide an access panel in the duct run or ceiling adjacent to the installed inline fan — inaccessible fans cannot be serviced or replaced when they next fail
Disclaimer
Information is general only. Exhaust fan airflow and system design must comply with AS 1668.2 for ventilation of buildings. Product selection must be confirmed against duct diameter, external pressure and the current manufacturer technical data sheet. Do not rely on this reference as a substitute for a mechanical engineer or licensed electrical contractor.