Vents VK 250 Q U centrifugal fan Ø 250 MM / 865 M³

A 250 mm centrifugal duct fan combining the quiet motor with the built-in thermostat and speed module. Rated 865 m³/h.

The VK 250 Q U deliberately delivers less air than the range can, and regulates what remains. That sounds like a half measure and is the opposite.

Choosing less output on purpose, and regulating it

The habit is to buy the largest fan that fits and turn it down afterwards. That works, but it is not always the best arrangement: a large motor permanently running at a fraction of its capacity costs more to buy and comes in a bigger housing you have to find room for.

This version does it the other way round. The quiet motor delivers 865 rather than 1080 m³/h, and the module regulates within that on temperature with an adjustable minimum. So you are not buying unused reserve, but you are buying the automation.

When that is the better choice: if your sum lands somewhere around 600 to 800 m³/h, your climate moves across the day, and you want the whole thing quiet. You then sit comfortably above your requirement at 865, run below your maximum most of the time thanks to the control, and get less velocity noise at the same airflow thanks to the Q motor.

When to take the standard version anyway: if your setup is growing, or if you are already close to 865 once filter and duct length are counted. Reserve you will genuinely use is not waste.

When setting up, watch the minimum speed. Do not set it to zero if you want continuous filtering: a carbon filter only treats the air that actually passes through it.

Construction

The quiet external rotor motor sits in the same housing as the rest of the range, with the control module on the front panel: a speed dial, a thermostat dial and two indicators. Otherwise a centrifugal impeller with backward-curved blades, self-recovering thermal cut-out, bearings for at least 40,000 running hours, plastic housing, IPX4 and class II.

Technical Specifications:

• Power draw: 108 W
• Current: 0.47 A
• Connection: 250 mm
• Volume flow: 865 m³/h
• Motor: quiet version, asynchronous, external rotor
• Control: built-in module, thermostat plus speed control
• Controls on: air temperature in the duct
• Thermal cut-out: recovers by itself
• Bearing life: at least 40,000 running hours
• Construction: corrosion-resistant plastic, IPX4, class II

Frequently asked questions

Why not buy the largest and turn it down?
You can, but you pay for reserve you do not use and get a bigger housing. If you will use that reserve, the standard is the better choice.

Can the minimum speed be zero?
It can, but your carbon filter then treats nothing at that moment. Set it low rather than off.

What is the difference from the VK 250 U?
The same module with the quiet motor: 865 instead of 1080 m³/h.

Does it control on humidity too?
No, temperature only. Humidity needs a separate climate controller.