















💨 Elevate your airflow game with silent, smart ventilation.
The CLOUDLINE S4 is a 4-inch inline duct fan delivering 205 CFM airflow at an ultra-quiet 28 dBA noise level. Featuring an 8-speed PWM controller and energy-efficient EC motor, it’s designed for versatile use in grow tents, hydroponics, AV cooling, and room ventilation. The kit includes all necessary hardware and a UK-compatible power plug, making it a plug-and-play solution for professional-grade climate control.




| Brand | AC Infinity |
| Model Number | AI-CLS4 |
| Colour | Pro Speed Controller |
| Product Dimensions | 9 x 19 x 30 cm; 2.56 kg |
| Power / Wattage | 21 watts |
| Voltage | 240 Volts |
| Noise Level | 28 Decibels |
| Special Features | High Velocity, Waterproof |
| Item Weight | 2.56 kg |
C**G
Quality product.
Quality product. Does the job it's meant to very nicely
A**R
Quite and the remote control is really excellent.
I replaced a built in fan in my kitchen extractor unit (failed motor) by mounting this unit in-line in the extract duct. The remote lead was long enough for me to mount the remote in my old unit and yet have the fan mounted well away. I mounted the fan on wires thus reducing any transmitted running noise (I would not expect much anyway as such a smooth running motor). The level of extraction is variable and perfect for the application. Excellent product 10/10. Fully recommend.
C**R
Brilliant
For me the ac infinity fans were a game changer, got my environment dialled in just how I need it and with ease to, I purchased an s6 and a t4 reasonably priced I might add, they work perfectly together! These fans are great quality and I was even more pleased when they already came with a connector attached to a U.K. plug! Overall 10 out of 10 for these fans, hats off to AC infinity, they’re so quiet and just a quality product, I will never use another make again, if you’re thinking about buying one just do it, you will not be disappointed
W**D
Ac
Works well
D**M
For best performance keep bends away from the fan
I really like this unit, it's powerful, it's quiet and the noisiest bit is the airflow. I am using it to blow air into a portable generator enclosure and the first thing I learnt was to make sure it has a good plenum to draw. I also found it works better if the outlet is not too close to a bend or obstruction or the back pressure affects it. But all of that is good HVAC design practice and for the money its very powerful if you wind it up.
E**D
Best fan money can buy!
This thing is just stupid, you really don't understand how good it is until you get it. It's gonna BLOW YOUR MIND if you are using a general brand extractor... the power is totally unmatched, it's fairly quiet and it's got a wee controller to set the speed of the fan which works VERY well. All in all, i don't know why I didn't buy this years ago - do it, do it, do it!! You will NEVER regret it!
S**N
Good fan
Best I've seen for less than a ton.
A**N
Go overkill for true silence.
Overall it is a great bit of technology, the smart features are invaluable. It is definitely NOT silent though. Past the 4th setting it begins being very noticeably "there" the higher you go (5-6-7-8-9-10) the louder it gets, until it just sounds like a jet engine. Make sure you don't have things laying around while you're testing it as it literally acts like a vacuum cleaner, will suck in your kid and your cat. Only buy this if it wont ever be running past 5th setting if you want quiet. Will work for small 4x4-5x5 spaces excellently. Another complaint is that on the pictures it is advertised with the controller 69, whereas I received the controller 67. The pictures are missleading.
D**N
パワー感は、どうかな? と、いった感じです。
A**Z
The brand is one of the better manufacturers selling to the general public and the vendor was very supportive and provided prompt service. I would buy from them again and recommend the inline fan without hesitation. It’s quiet at lower settings and works without issue.
C**D
Good quality. Very quiet.
C**O
Do not cheap out on fans. Buy one of these. I've got a handful of cheap ebay fans in a pile in the garage and none come even remotely close to the cloudlines. You get what you pay for and these are an absolute testament to that. I've purchased 4 of the AC Infinity products now in varying sizes and every single product is a 10/10 including all the adapters/fittings they sell.
D**D
This inline fan works great — super quiet and powerful, exactly what I needed to improve airflow in a small space. It moves a lot of air without the loud hum you get from cheaper fans. Installation took a bit of fiddling to get everything sealed properly, but once it was set up, it ran smoothly. Really happy with the quality and performance.
Trustpilot
Hace 2 meses
Hace 3 semanas