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

A 125 mm centrifugal duct fan rated 355 m³/h. Plastic casing, external rotor motor with self-resetting overheat protection and ball bearings rated for at least 40,000 hours.

The VK 125 R is the standard version one size up from the 100 mm. That choice, 100 or 125, is where most people get stuck.

100 or 125 millimetres

The difference in airflow is larger than the difference in diameter suggests: 355 against 250 m³/h, better than forty percent more air. That is because flow area grows with the square of the radius rather than linearly.

The temptation is to take the smallest one that delivers enough on paper. That is usually the more expensive choice, for two reasons.

The first is resistance. The number on the box applies with nothing attached. Add a carbon filter and a few metres of ducting and you keep a part of it, and the tighter you started the harder that lands.

The second is noise. A fan running at half power is considerably quieter than a smaller one working flat out. Noise comes mostly from air velocity, and a larger cross-section moves the same air more slowly.

The rule of thumb that follows: work out your space, volume in cubic metres times sixty for one air change per minute, then pick the size that sits above that with margin rather than the one that just reaches it. If that costs you space, it is a real objection; if it only costs money, it pays itself back in quiet.

What else makes 125 mm easy: ducting, clamps and carbon filters in this size are available everywhere, as they are in 100 mm.

Build and mounting

The plastic housing does not rust and therefore tolerates the damp air of an extraction run. If the motor gets too warm it backs off, and it picks up again by itself once cooled.

Brackets are included; wall, ceiling or floor makes no difference and upright is fine too. Before fixing anything, look at where the arrow on the housing points, because that decides which way the air travels.

Technical Specifications:

• Power draw: 79 W
• Current: 0.34 A
• Duct size: 125 mm
• Capacity: 355 m³/h
• Impeller: centrifugal with backward-curved blades
• Drive: asynchronous external rotor, cut-out recovers by itself
• Bearing life: at least 40,000 hours
• Housing: corrosion-resistant plastic, IPX4, class II
• Permitted environment: +1 to +45 °C at up to 80 percent RH
• Mounting position: your choice

Frequently asked questions

Is 125 mm overkill for a 100 x 100 cm tent?
No. That tent asks for 120 m³/h for one air change per minute, and this fan delivers that at a low setting, which is quieter than a 100 mm at full power.

Can I turn it down?
Yes, with an external speed controller. For two built-in speeds there is the Duo, for automatic control the U version.

Will a 125 mm carbon filter fit?
Yes, and they are readily available. Do size the filter generously so it does not become the bottleneck.

Can it hang vertically?
Yes, horizontal and vertical are both allowed.