Vents 125 Quietline DUO Inline Fan 145-197m³/h

A quiet 125 mm duct fan with two speeds: 145 or 197 m³/h.

The 125 Quietline DUO is the largest quiet version we stock. That brings into view the question this whole range runs up against.

Quiet or capable, not both

At 197 m³/h on high this fan sits well above the other Quietline models. Even so it stays below what an ordinary centrifugal of the same size does: our VK 125 reaches 355 m³/h.

That is not a shortcoming but the design. You buy quiet by moving less air, and wanting more air buys noise back. Any fan claiming to deliver both is measuring somewhere else or not comparing fairly.

So the practical limit is your system's resistance. Without a filter, on short ducting, 197 m³/h covers a small to medium space and stays quiet. Add a carbon filter and that changes: the filter demands pressure, this range is not built for it, and too little survives.

If you want quiet and filtering, the route is a larger centrifugal fan turned down, possibly with a silencer in the run. A fan with headroom running gently is quieter than a quiet one working flat out.

Technical Specifications:

• Duct: 125 mm
• Capacity low: 145 m³/h
• Capacity high: 197 m³/h
• Application: spaces without a carbon filter where noise decides

Frequently asked questions

Can this handle a carbon filter?
No. This range is built for quiet, not for pressure. Take a centrifugal fan and turn it down instead.

Why does it deliver less than the VK 125?
Because quiet and airflow exclude each other: less air through the same cross-section means less noise.

When do I use the low speed?
As continuous baseline ventilation; the high speed for peaks.