AC Infinity CLOUDLINE S4
#2 in 4 inFull review
A quiet, efficient 4 in fan for small grow tents, closets and AV cabinets. The S line adds a longer cord and more airflow than the cheaper A4.
Amazon $89.99$89.99
The AC Infinity CLOUDLINE S4 is the better inline duct fan overall, rated 3.6 to 3.2. The AC Infinity CLOUDLINE S4 leads on airflow. The Hon&Guan PRO 4 in Inline Fan wins on value. The Hon&Guan PRO 4 in Inline Fan costs $26 less ($63.99 vs $89.99).
Prices were last checked November 9, 2026. Product prices and availability are accurate as of that date and are subject to change; the price and availability shown on Amazon or the retailer's site at the time of purchase apply. As an Amazon Associate we earn from qualifying purchases.
Hon&Guan PRO 4 in Inline Fan
#5 in 4 inFull review
A low-cost 4 in EC fan with strong rated airflow. Its power draw is not published, which keeps it below documented rivals.
Amazon $63.99$63.99
Which should you buy?
- Choose the AC Infinity CLOUDLINE S4 for airflow (226 CFM through 4 in duct vs 212 CFM through 4 in duct).
- Choose the Hon&Guan PRO 4 in Inline Fan for value ($30.18 per 100 CFM ($63.99, 212 CFM) vs $39.82 per 100 CFM ($89.99, 226 CFM)).
Scores side by side
Each factor is scored 0-100 against the same fixed reference points for every 4 in inline duct fan; a clear win is highlighted. How we rank explains each one.
| Factor weight | AC Infinity CLOUDLINE S4 | Hon&Guan PRO 4 in Inline Fan |
|---|---|---|
| Overall rating | 3.6/5 | 3.2/5 |
| Value 25% | 47 $39.82 per 100 CFM ($89.99, 226 CFM) | 78 $30.18 per 100 CFM ($63.99, 212 CFM) |
| Efficiency 25% | 56 8.1 CFM per watt (226 CFM, 28 W) | 0 power draw not published, scored as the lowest |
| Airflow 15% | 88 226 CFM through 4 in duct | 77 212 CFM through 4 in duct |
| Noise 15% | 97 26 dBA at full speed | 91 28 dBA at full speed |
| Controls 10% | 40 speed controller included | 40 speed controller included |
| Warranty 10% | 25 2-year warranty | 0 warranty not published, scored as none |
Specifications
| AC Infinity CLOUDLINE S4 | Hon&Guan PRO 4 in Inline Fan | |
|---|---|---|
| Performance | ||
| Duct size | 4 in | 4 in |
| Rated airflow | 226 CFM | 212 CFM |
| Static pressure (not scored) | 223 Pa | - |
| Power at full speed | 28 W | - |
| Power figure | Max power draw | - |
| Average power (not scored) | 21 W | - |
| Airflow per watt | 8.1 CFM/W | - |
| Price per 100 CFM | $39.82 | $30.18 |
| Noise at full speed | 26 dBA | 28 dBA |
| Top speed | 2,800 RPM | - |
| Controls | ||
| Motor | EC | EC |
| Controller | 10-speed controller | Stepless speed controller |
| Speeds | 10 | Stepless |
| Temperature and humidity control | No | No |
| Phone app | No | No |
| Timer or cycle modes | No | No |
| Build | ||
| Housing | Plastic | Metal |
| Ingress rating | IP44 | IP42 |
| Voltage | 100-240 V | - |
| Warranty | 2 years | - |