Vents VK 125 Duo R centrifugal fan Ø 125 MM

A 125 mm centrifugal duct fan with two speeds: 191 or 329 m³/h, selected with a thyristor two-speed controller.

The VK 125 Duo R has two speeds the motor was designed for. The question is what you do with the second one, and the answer is usually: cut your day in two.

Setting a day and a night speed

Your ventilation demand is not constant. With the lights on, heat has to leave and you want all the air you can get: that is the high speed, here 329 m³/h. During the dark period no heat is being added, but you still want air moving against humidity around the leaves, and 191 m³/h is ample for that.

Switching by hand works, but remembering twice a day is exactly the sort of task that slips after a week. An ordinary timer solves it: it switches between the two speeds at the times you set, so your ventilation follows your light schedule without you thinking about it.

Two things to watch with that setup. The timer has to be rated for the fan's power, which is on the type plate. And match the speeds to your light schedule rather than to your own day: what matters is when the lamps come on, not when you get up.

If you would rather switch on temperature, this is not the version for it: look at the U version with its built-in thermostat, or a separate climate controller with a probe you hang yourself.

Build

The housing is plastic that does not corrode, which counts in a damp extraction run. The impeller is balanced during assembly, and the external rotor motor recovers by itself after an overheat.

Technical Specifications:

• Power draw: 45 W on low, 58 W on high
• Current: 0.21 A to 0.26 A
• Duct size: 125 mm
• Low speed: 191 m³/h
• High speed: 329 m³/h
• Motor: two-speed, external rotor, cut-out recovers by itself
• Control: thyristor two-speed controller
• Bearing life: at least 40,000 hours
• Housing: corrosion-resistant plastic, IPX4, class II
• Mounting position: your choice

Frequently asked questions

Can the speeds switch automatically?
With a timer rated for the fan's power, yes. Switching on temperature is not possible with this version.

Which speed for the dark period?
Usually the 191 m³/h low speed. No lamp heat is being added, but the air keeps moving.

Is the high speed as strong as the standard VK 125?
Almost: 329 against 355 m³/h. The gain is the low speed you get with it.

Can I run several fans from one controller?
Yes, as long as total power stays within the controller's rating.