Vents VK 125 U centrifugal fan Ø 125 MM / 355 M³

A 125 mm centrifugal duct fan with a built-in electronic module: thermostat and speed control in one, rated 355 m³/h.

The VK 125 U is the standard VK 125 with the control module on the front. That a duct fan needs such a module is not incidental: the manufacturer specifies it.

Why Vents specifies a speed controller

The manual for this range states that a speed controller and local demand control must be used. That is not a sales line but a design assumption: these fans are meant to run regulated, not pinned at full power.

There is a practical reason behind it that shows up on your electricity bill. A fan running at a hundred percent all day moves the volume of air you only need at your heaviest moment. Regulating means reserving that peak for when it is needed and running cheaper and quieter the rest of the time.

On this version that regulation is built in. On the front panel one dial sets the speed and the other the temperature threshold, and the module does the rest. Two indicators show whether the thermostat is active and whether there is power.

What that saves is not only electricity. A separate thermostat and a separate speed controller are two devices on the wall, two lots of wiring and two things that can fail. On the U version it sits in the fan, where the sensor reads duct temperature directly.

If you would rather not have the fan regulate itself but fold it into a larger system, that works too: take the standard R version and hang it on the climate controller you already have.

Build

The fan itself is unchanged from the VK 125 R: centrifugal impeller with backward-curved blades, self-resetting overheat protection, ball bearings for at least 40,000 hours, corrosion-resistant plastic casing, IPX4 and horizontal or vertical mounting.

Technical Specifications:

• Power draw: 79 W
• Current: 0.34 A
• Duct size: 125 mm
• Airflow: 355 m³/h
• Control: built-in module with thermostat and speed control
• Measuring point: air temperature inside the duct
• Protection: self-resetting overheat cut-out
• Bearings: ball, at least 40,000 hours
• Casing: corrosion-resistant plastic
• Ingress protection: IPX4, class II
• Mounting: horizontal or vertical

Frequently asked questions

Do I need a separate controller with this?
No. Thermostat and speed control are in the module on the fan.

Can I still run it from my own climate controller?
The standard VK 125 R is the logical choice then; it is meant for an external controller.

Where does the sensor measure?
In the duct, inside the fan itself, not in the room.

Does it deliver as much as the standard version?
Yes, 355 m³/h. The difference is the control module.