Vents VK 100 U centrifugal fan Ø 100 MM / 250 M³

A 100 mm centrifugal duct fan with a built-in electronic control module: thermostat and speed control in one, rated 250 m³/h.

The VK 100 U is the same fan as the VK 100 R with a control module on the front. That module does more than switch on and off, and it pays to know its three modes before you set it up.

Three ways the thermostat can work

The front panel carries two dials, one for speed and one for the temperature threshold, plus two indicators showing whether the thermostat is active and whether the fan has power. What happens when that threshold is reached depends on the mode.

Mode U. The speed dial sets the minimum airflow: the level the fan runs at while it is cooler than your threshold. When the set temperature is reached, the motor steps up to maximum. It only steps back down once the duct temperature falls two degrees below your threshold.

Those two degrees are not sloppiness, they are the point: without that gap the fan would hunt back and forth around the switching point. It is the same idea as a buffer on a climate controller.

Mode U1. Works like U, with different behaviour above the threshold.

Mode U2. Here the speed dial simply sets the running speed, and the fan stops once the duct reaches your set temperature. This mode enforces a minimum switching cycle of five minutes so it cannot cycle constantly.

For extraction that has to respond to heat, mode U is usually the right one: a baseline speed all the time, faster when it gets too warm. U2 suits applications where the fan is genuinely allowed to stop.

What you get for it

The module makes a separate thermostat and a separate speed controller unnecessary, so that is two devices off the wall and the wiring between them. The fan itself is unchanged: centrifugal impeller, self-resetting overheat protection, ball bearings for at least 40,000 hours, IPX4, and horizontal or vertical mounting.

Technical Specifications:

• Power draw: 80 W
• Current: 0.34 A
• Duct size: 100 mm
• Airflow: 250 m³/h
• Control: built-in module with thermostat and speed control
• Modes: U, U1 and U2
• Step-down in mode U: two degrees below the threshold
• Minimum switching cycle in U2: five minutes
• Protection: self-resetting overheat cut-out
• Bearings: ball, at least 40,000 hours
• Ingress protection: IPX4, class II
• Mounting: horizontal or vertical

Frequently asked questions

Do I still need a separate thermostat?
No. Thermostat and speed control are in the module on the fan.

Why does it only step down two degrees lower?
That gap stops the fan hunting back and forth around the threshold.

Can the fan switch off completely on temperature?
In mode U2, yes. In mode U it keeps running at the minimum you set.

What is the difference from the VK 100 R?
The same fan without the control module. The R needs an external controller.