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AC Infinity

AC Infinity RAXIAL S4, Inline Booster Duct Fan 4” with Speed Controller - Low Noise Inline HVAC Blower Can Fan for Basements, Bathrooms, Kitchens, Workshops

Based on 8,339 reviews
Condition: New
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$34.99
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Availability: In Stock.
Fulfilled by Amazon
Arrives Tuesday, Nov 3
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At a glance

Condition
New
Size
4"
Model
AC-RXS4
Dimensions
7.28"D x 3.95"W x 3.95"H
Weight
2.07 lb
Color
Black
Electric fan design
Blower
In the box
Cord

Features 5

  • A duct fan designed to increase existing airflow in HVAC systems and ventilate home spaces like attics and workshops.
  • Features a variable fan speed controller, enabling you to optimize airflow and noise level for any application.
  • Unibody die-cast construction with no welded seams; reduces vibration while ensuring smoother airflow.
  • AC shaded-pole induction motor utilizing balanced steel blades and permanently lubricated ball bearings.

Specs 28

Brand AC Infinity
Color Black
Electric fan design Blower
Power Source AC
Style Duct Fan
Product Dimensions 7.28"D x 3.95"W x 3.95"H
Room Type Basements, Bathrooms, Kitchens, Workshops
Special Feature Speed Controller

Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Tuesday, Nov 3

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

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View our full returns policy here.

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Leasing options through Acima may also be available during checkout.

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Top Amazon Reviews

Great value.
Size: 6"
Works like a dream.
Reviewed in the United States on November 11, 2025 by Kikeh
Downdraft mechanical ventilation for saunas
Size: 4"
This is the fan Sauna Marketplace recommends in our guide to add downdraft mechanical ventilation to outdoor sauna kits to improve airflow and the temperature gradient. The result is a more comortable sauna you can stay in longer, with safer CO2 levels. This fan is the simplest and works well with HUUM, Harvia, and Saunum controllers. ... show more
Reviewed in the United States on September 29, 2025 by Sauna Marketplace
Not sure about the noise level
Size: 6"
I bought this S6 fan to create some circulation in my basement The fan works well and seems to be well-made. My basement is about 2000 sq feet and is chopped into these three main areas: Space A. Unfinished area (about 350 sq feet) Space B. Main living area (about 1200 sq feet) Space C. Exercise/rec room. (450 sq feet) Space A connects to Space B via a door. Space B connects to Space C through another door. Space C does not connect to Space A directly. We have a humidity/mold problem throughout the basement, so I installed a dehumidifier in Space A. I wanted to pull air from Space C over the wall into Space A then push it out to Space B and back to Space C to complete the cycle. I am hoping that by circulating some air through space A the dehumidifier will dry out the whole basement over time. My dehumidifier is rated to process 160/190 cfm on its two speed settings. So I bought this 265 cfm AC Infinity S6 fan and 8' of 6" flex duct from AC Infinity as a circulation fan. My configuration is as follows: I cut a a 6" round opening in the Space C ceiling. I put a 90" hard elbow there and attached the 8' of 6" duct that terminates in Space A. In Space A at the other end of the duct I mounted this fan onto a 12x4x6 90-degree register box and a 12x4 diffuser. I hope to pull over some air from Space C past the dehumidifier. Issue: After completing the install, the noise level in Space C at all fan speeds (where the intake vent is) is higher than I would have liked. I measured some dB readings with my iphone app and here are the results. [NOTE: For reference, in this next part I am looking at the speed control's dial like a clock face, where you have the "off" position at the 6:00 (bottom) position. Then "Low" is at 8:00. "Medium" is at 12:00 (top). And "High" at 4:00 position.] While the controller seems infinite, there are really only three or four distinct areas of power/noise: At the 8:00 and 9:00 position, the noise level in space C is about 40 dB. At 10:00 position it jumps to 49 dB (nearly ten times louder). At 11:00 - 12:00 it is about 52 dB. Then at the 1:00 position it jumps to 54 dB and doesn't really get much louder from there. Recall that the dB scale is logarithmic, not linear. If there is a relationship between noise and cfm, then between the 1:00 position and 4:00 position, it seems there is very little air volume increase. I am not an HVAC engineer nor a sound expert, but it seems you have a low 40-ish dB setting, a low 50-ish dB setting and then a 54 dB setting, all as measured on the inlet-side vent, which for me is 8' from the fan. I would like to make it quieter in Space C because my wife spends a lot of time down there, and she doesn't tolerate noise well. I don't really care about the noise level in space A, as it is not occupied and the dehumidifier (generating 52 - 54 dB) is in there too. But for reference, with the fan attached right to the register outlet box, the noise levels in Space A (without the dehumidifier running) are 2 - 4 dB higher than the above readings from under the inlet vent in Space C. Note: I have 9' basement ceilings, and I took all measurements directly beneath the vents at 5' up from the floor. Not a scientific result, but I hoped to give you all some idea of the noise levels. ... show more
Reviewed in the United States on September 5, 2021 by KWC Indy
4” inline exhaust fan for smaller grow tents
Size: 4"
Reliable adjustable speed exhaust fan, quiet, durable, able to draw air thru a carbon filter, AC Infinity quality
Reviewed in the United States on October 13, 2025 by Best Dad Ever
Very nice and quiet
Size: 6"
It's adjustable and can be made very quiet. Perfect for what I needed.
Reviewed in the United States on October 9, 2025 by JRJB
Quiet motor but loud wind noise
Size: 6"
So I tried the hon&gaun, ac infinity raxial s6 and ac infinity cloud line pro s6. The hon&gaun definetly moved the most air for the money but it was the only one that I could here the motor running both standing next to it and at the end of the vent over 20 feet away even running only 40%. But even at 40% it still moved a lot of air and there was not too much turbulence so the air noise was minimal but motor noise was loud. I really don’t recommend this unless it is somewhere we’re the noise doesn’t matter. The ac infinity raxial was the opposite, a bit more money, moves far less air, the motor is silent but the lousy impeller creates a lot of turbulence creating a lot of air noise that is mainly heard at the end of the vent. Last was the ac infinity cloudline pro, it’s far more expensive but far superior, moves lots of air, motor can’t be heard even standing right next to it and the air flow is smooth and quiet. It also offers optional WiFi controller that is very easy to use, can control up to 4 fans which can be controlled by your phone, by set speed, schedule, atmospheric pressure readings, temperature or humidity. This allows you to put the probe in a vent and have the fan only run when ac, heat or humidifier are running. ... show more
Reviewed in the United States on June 28, 2024 by Adam
Using as an attic ventilator. Low noise/vibration, satisfied with performance.
Size: 8"
Review Image by David P. David P.
Review Image by David P. David P.
This review is for AC Infinity RAXIAL S8, Inline Booster Duct Fan 8” with Speed Controller - Low Noise Inline HVAC Blower Can Fan for Basements, Bathrooms, Kitchens, Workshops. The fan was delivered on-time, complete, and as described by the seller. It was well-packaged in a custom box and included a user manual, 2-year warranty information, and hardware for mounting the speed controller. The cylindrical structure is sturdy and nicely finished, the plug-in power cable and speed controller are integrated and the fan runs smoothly with little vibration. The speed is continuously variable with a dial control from OFF to maximum; at highest speed it makes about as much noise as a pedestal fan….. the sound is principally from the airflow itself. The fan has steel blades and is designed to be mounted/suspended inline in an 8-inch diameter ductwork; there are no mounting brackets provided. I am using this fan, funning at medium speed, to increase ventilation in my attic with the expectation of improving the efficiency of my A/C system (also installing a reflective radiant barrier throughout); so far I am satisfied with the performance. I am using an Amazon Smart Plug with the Alexa application to run the fan on a regular routine and/or use voice commands to turn on and off remotely as needed. ... show more
Reviewed in the United States on January 25, 2025 by David P. David P.
Works well, easy set up.
Size: 8"
Works as it should, easy to set up.
Reviewed in the United States on September 13, 2025 by Paul
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