Ventilation Fans – Silent Inline Duct Fans
Astberg ventilation fans are engineered for quiet, high-efficiency air extraction in bathrooms, kitchens, and commercial ducted systems. Our inline duct fan range spans 100mm to 315mm, with airflow from 147 m³/h up to 2,206 m³/h (87–1,300 CFM equivalent), covering everything from a small ensuite to a large commercial washroom.
Each ventilation fan uses a mixflow or EC motor design for low-noise operation, corrosion-resistant housing, and easy inline mounting into round ducting — ideal for retrofits where a ceiling-mount fan won't fit. Variable-speed EC models let you tune airflow to the room, cutting running costs versus fixed-speed AC fans.
Not sure what size ventilation fan you need? Use the Duct Fan Size Calculator below to match CFM/CMH to your room dimensions and air-changes-per-hour (ACPH) requirement.
How to Choose the Right Ventilation Fan
Picking the right ventilation fan comes down to four specs. Match these to your room and ducting before you buy:
1. Airflow (CMH / CFM)
Airflow tells you how much air the fan moves per hour, measured in cubic metres per hour (m³/h or CMH) or cubic feet per minute (CFM). Match this to your room size and the recommended air changes per hour (ACPH) — a small bathroom typically needs 10–12 ACPH, while a kitchen needs around 6 ACPH.
2. Noise Level (dB)
Mixflow ventilation fans are designed to run quietly, making them suitable for bedrooms, ensuites, and occupied spaces. If noise is a priority, look for models specifically marketed as "silent" or "super silent."
3. Duct / Pipe Diameter (mm)
Inline ventilation fans must match your existing or planned ducting diameter — common sizes are 100mm (4"), 125mm (5"), 150mm (6"), 200mm (8"), 250mm (10"), and 315mm (12"). Buying the wrong diameter means additional reducers or lost efficiency.
4. Power Consumption (W) & Motor Type
Standard AC motor fans are cost-effective for simple on/off use. EC (electronically commutated) motor fans cost more upfront but offer variable-speed control and lower running costs, especially where the fan runs for long periods.
Ventilation Fan FAQs
What size ventilation fan do I need for my bathroom?
For most residential bathrooms, aim for 10–12 air changes per hour. A small bathroom (up to 4m²) is typically covered by a 100mm fan rated around 150–200 CMH, while larger or ensuite bathrooms with a shower or bath usually need a 125mm or 150mm fan rated 280–530 CMH. Use the Duct Fan Size Calculator above for a precise recommendation based on your room dimensions.
What's the difference between an inline fan and a ceiling exhaust fan?
A ceiling exhaust fan mounts directly in the ceiling above the room it ventilates. An inline ventilation fan sits within the ductwork itself — often in a loft, ceiling void, or remote location — and is connected to one or more grilles via ducting. Inline fans are quieter at the point of use since the motor is set back from the room, and one unit can often serve multiple rooms.
How noisy is a ventilation fan?
Noise varies by model and motor type. Mixflow and EC-motor ventilation fans are built for quiet operation and are suitable for bedrooms and living spaces, while standard fans running at higher CMH ratings will produce more audible noise. Check the decibel (dB) rating listed on each product page before buying if noise is a concern.
Can a ventilation fan be installed outside the bathroom?
Yes — this is one of the main advantages of an inline ventilation fan. Because it connects via ducting rather than sitting in the ceiling, it can be installed in a loft space, cupboard, or ceiling void away from the room, reducing noise and freeing up ceiling space in the bathroom or kitchen itself.
Do I need an EC motor or a standard AC motor ventilation fan?
Choose an EC motor fan if you want variable-speed control, quieter operation, and lower long-term running costs — ideal for spaces where the fan runs frequently or for extended periods. A standard AC motor fan is a more budget-friendly option for simple, intermittent on/off ventilation needs.
