AC Infinity CLOUDLINE Pro T6

A 150 mm inline fan, 402 CFM (683 m³/h) at 32 dBA, supplied with the Controller 69 Pro and a climate probe. Controls on temperature, humidity and VPD.

The CLOUDLINE Pro T6 is the brand's most-bought combination: the 150 mm fan with the smart controller included. Anyone setting it up for the first time runs into the same problem.

Stopping the fan from hunting

You set a high temperature trigger, the fan comes on, the temperature drops half a degree, and it falls back again. A moment later it starts over. That toggling is tiring to listen to and does not make your climate steadier, it makes it choppier.

The controller has two settings for this. The first is transition: it sets how much further the temperature has to climb before the fan steps up a level. Set it to zero and it jumps straight to its maximum the moment your trigger is crossed. Set it to two degrees and it climbs one step at a time along with the temperature.

The second is buffer: it places the switch-off point below the switch-on point. With a high trigger of 28 degrees and a buffer of 3 degrees the fan starts at 28 and only drops back at 25. That removes the hunting, because the temperature has to genuinely fall before it backs off.

Transition is adjustable from 0 to 10 degrees, and from 0 to 10 percent for humidity. In practice a small value works best: large enough to remove the toggling, small enough to stay responsive. Start at two degrees and watch it for a day.

Controlling on VPD instead of humidity

Besides temperature and humidity this controller can drive on VPD, with a high and a low trigger. VPD is the vapour pressure difference between the leaf and the air around it, expressed in kPa, and that figure sits closer to what the plant experiences than temperature and humidity separately.

Why that matters: 70 percent humidity at 20 degrees is a completely different thing from 70 percent at 28. Warm air holds far more moisture, so at the same 70 percent there is a much stronger pull on your leaves at 28 degrees. Drive on humidity alone and that pull changes all day with your temperature without you seeing it. VPD captures both in one number.

There is also a leaf offset to set. Leaves are usually a little cooler than the surrounding air because of transpiration, and that correction has the controller calculate from leaf temperature rather than air temperature.

Commonly used reference bands per stage, as a starting point rather than a rule:

These vary by crop and variety, so treat them as a point of departure and watch your plants. What does hold generally: pick one quantity to drive on. Drive on humidity and VPD at the same time and the two work against each other the moment your temperature moves.

Technical Specifications:

• Model: AI-CLT6
• Duct size: 150 mm (6 inch)
• Airflow: 402 CFM (683 m³/h)
• Noise: 32 dBA
• Static pressure: 394 Pa
• Power draw: 61 W maximum
• Controller: Controller 69 Pro, four ports, probe included
• Transition range: 0 to 10 degrees, 0 to 10 percent humidity
• Buffer range: 0 to 10 degrees
• VPD: high and low triggers, with adjustable leaf offset
• Connectivity: Wi-Fi on 2.4 GHz and Bluetooth
• Motor: brushless EC motor with PWM control
• Bearings: dual ball, 67,000 hours
• Ingress protection: IP44
• Fan dimensions: 21.2 x 32.0 x 20.0 cm

Frequently asked questions

My fan switches on and off every few minutes. What now?
Set a buffer of a few degrees so the switch-off point sits below the switch-on point, and give transition a small value.

Is the fan the same as the S6?
Yes. The difference is the controller and the included probe.

Does the app work on any Wi-Fi network?
Only on 2.4 GHz. Make sure your phone is not on the 5 GHz network while pairing.

Should I drive on humidity or on VPD?
Pick one. VPD is more accurate because it accounts for temperature, but driving on both lets them work against each other.

What is the leaf offset?
A correction for leaves being cooler than the air around them, so the controller calculates from leaf temperature.

Where should the probe hang?
At canopy height, at the warmest or most humid point, with the protective cap removed.