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Availability:
15 left in stock
Arrives
Tuesday, Oct 13
Color: Bronze
Size: 4” x 10"
Features
- Next-Gen Ventilation: Intelligent register booster fan automatically responds to HVAC-driven temperature changes to improve airflow, helping eliminate hot and cold spots for consistent comfort in every room.
- Smart Vent System: Electronic vents automatically open when your HVAC system activates to maximize boosted airflow, then close when inactive to help prevent dust, pests, and debris from entering.
- Intelligent Controls: LCD display provides real-time room temperature monitoring and easy access to customizable cooling and heating triggers, fan speeds, timers, and operating settings for climate control.
- Smart Remote Access: Use the included IR remote for quick control, connect with Alexa or Google Home for voice commands, and unlock smart alerts, data charts, and advanced automations through the app.
- Measure Before Purchase: Designed exclusively for 4 x 10 in. duct openings, engineered with dual-ball bearing fans powered by a precision PWM-controlled motor, delivering powerful whisper-quiet airflow.
Description
AC Infinity is a technology company that specializes in environmental controls for audio/video and HVAC. The company was founded on the principle of working closely with customers to develop great products. Dependable service and a commitment to product quality are the foundations of the business's values. Control with IR remote, enable smart voice commands, and access app automations, charts, and alerts. Create automation for your devices to systematically manage your environment. Set customizable alerts that can trigger in response to almost any event. An interactive graph intuitively displays temperature data. Input target figures to help your environment approach and maintain your ideal climate. Stay on top of what's happening in your space using alerts and notifications so you can quickly counteract any environmental spikes.
Brand: AC Infinity
Color: Bronze
Electric fan design: Exhaust Fan
Power Source: Corded Electric
Style: Contemporary
Product Dimensions: 1.96"D x 11.54"W x 5.51"H
Room Type: Bedroom
Special Feature: Bladeless
Recommended Uses For Product: Air Circulation, Cooling
Mounting Type: Free Standing
Power Source: Corded Electric
Room Type: Bedroom
Special Features: Bladeless
Recommended Uses For Product: Air Circulation, Cooling
Mounting Type: Free Standing
Controller Type: Button Control
Number of Speeds: 10
Noise Level: 18 db
Wattage: 6 watts
Air Flow Capacity: 120 cfm
Voltage: 12 volts
Indoor Outdoor Usage: Indoor
Control Method: App
Standby Power Shutoff: 20 CFM per watt
Number of Power Levels: 10
Motor Type: DC
Installation Type: surface-mounted
Material: Aluminum
Blade Material: Plastic
Color: Bronze
Electric Fan Design: Exhaust Fan
Style: Contemporary
Finish Type: Brushed
Collection Name: Duct_Fans
Item Dimensions D x W x H: 1.96"D x 11.54"W x 5.51"H
Item Weight: 0.27 g
Size: 4” x 10"
Brand Name: AC Infinity
Included Components: Cord
Model Name: AC-RBF4-B
Model Number: AC-RBF4-B
Manufacturer: AC Infinity
UPC: 819137020238
Number of Packs: 1
Unit Count: 1 Count
Part Number: AC-RBF4-B
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Tuesday, Oct 13
Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
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Top Amazon Reviews
Color: White
Size: 4” x 12”
Installed the 4x12 AIRTAP T4 a week ago in a large upstairs bedroom that gets considerably hotter than the rest of the house. It also has low airflow from the two existing registers. Installed the airtap and at 40% speed level the noise was suitable for sleeping. The temperature did cool down a degree or two. For the "test" the door was closed as it would be at night. I've increased the speed to 70% which is too loud for sleeping but, if used to cool the bedroom for a few hours before bed, it now keeps the temp very close to the rest of the house (1-2 degrees warmer). I set the sensor to a temperature (in the duct) to be higher than the room and it continues for some time after the AC shuts off while there is still cool air in the duct. It met our expectations and does cool the room well. No problem with installation. Directions are in very small font and difficult to read. Look them up online,much easier.
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Reviewed in the United States on August 23, 2026 by Raven49
Color: White
Size: 4” x 10"
This is one of the best vent boosters on the market, and I say that after using three other brand vent boosters over the last four years. I’ve owned three versions of this AC Infinity booster—the original one with no connectivity, the second version with a larger display but no Bluetooth, and now this latest one with Bluetooth and a remote. I have noticed the company is constantly improving design and quality, and the current version may be different from mine. The review model of mine is by far the most refined and feature-rich. I have five bedrooms upstairs, and even after recently upgrading my HVAC system to a high-98-efficiency furnace with a variable-speed ECM motor and inverter AC condenser, I was still getting less airflow upstairs compared with the downstairs rooms. Especially when my inverter HVAC ramps down the speed, it is most noticeable upstairs as airflow becomes very low. My house was built around 2000, with the HVAC system located in the basement and 6-inch hard ducting supplying the upstairs bedrooms and downstairs. Some of the upstairs bedrooms are larger or have only one vent, so I wanted to improve and balance the airflow. I have used AC Infinity vent fans in all of the upstairs bedrooms with both the current and previous models, and they have helped improve airflow to those rooms. The difference is especially noticeable in rooms that naturally receive less air from the main HVAC system. These units have been useful for helping distribute the conditioned air more evenly throughout the upstairs area. The build quality is excellent. The whole body is made with metal and is sturdy. The two internal fans use good quality bearings, so they run very quietly and very smoothly. I did take it apart, and the fans are voltage-controlled, not PWM. However, the speed curve is very smooth. The unit offers 10 fan speeds with flawless, gradual ramping from 0 to 10. The difference in noise level and airflow smoothness compared to cheaper boosters is huge. I have uploaded a video so you can hear the noise level from 1 to 10. Definitely, speed 10 is loud, but I found speed 7 to be the most comfortable for good airflow and noise, and I have set all of them in my upstairs bedroom. Installation was pretty easy for me; you have to make sure the sizing of your vent is correct. Just take out the old vent cover and put it in. I did not find any difficulty, and it was perfectly seated and tightly sealed so that it does not suction the air from outside the HVAC vent. I did use some foam when there was a gap and advise using some foam seal, which you can easily find on Amazon. What truly sets this vent booster apart is that it’s a genuine smart device. You can set both heating and cooling temperature setpoints, and the booster automatically activates when your chosen temperature is reached by your HVAC and adjusts fan speed on its own. It only runs when the HVAC vent reaches the setpoint and turns off afterward when the vent temp drops below the setpoint temp. The best part is that even after the furnace or AC turns off, the booster can continue pulling the remaining warm or cool air from inside the ducts until the temperature drops below your set point, which adds extra comfort and efficiency—especially in upstairs rooms. The AC Infinity app is a major upgrade. You no longer need to touch the unit at all, which is extremely useful if your vent is under a bed or in a hard-to-reach position. The app connects via Bluetooth and gives you full customization options, including temperature monitoring, mode changes, and precise automation. My first version from four years ago had none of these smart features, and adjusting it manually was inconvenient. This new model fixes all of that with excellent remote control and easy automation. The app is also easy to understand and has descriptions of functions. There are several other strong points worth mentioning. The display is large, bright, and easy to read. You can also turn it off at nighttime to avoid light bleed. The interface and options are simple to understand, even for beginners. The buttons are very tactile and satisfying to press. The power cord is also generously long, making placement much easier than short-corded boosters. The one con I can find is that the loudness of the fan depends on the duct size. If the duct is small and you set the fan high, it will create a high-pitched noise because it is starving for air. So definitely play with the speed level to see which speed provides the quietest and best airflow. For my 6-inch duct, I found that a 7-speed level offers the best noise and performance ratio. Overall, I highly recommend this vent booster without any hesitation. A couple of my family members bought this after seeing it at my home. It costs a little more, but the performance, build quality, smart features, overall quiet operation, and good airflow make it absolutely worth the investment compared to the many low-quality alternatives on the market.
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Reviewed in the United States on October 17, 2025 by SMH
Color: Bronze
Size: 4” x 12”
Like almost everyone else here, I found that these gadgets really work. I have a 4th floor attic room that gets essentially no air because the blower is on the 1st floor. It tends to sit 5-10F above setpoint in the summer depending on the outside temperature (I have a floor fan in the room with a temp sensor and data logging in an app, very handy for monitoring this install). The room is basically the entire top floor of the house, >300sqft. One device only pushed the temperature down about 2F, but adding a 2nd got it down to within a couple degrees F of setpoint and is a huge boost in quality of life on that floor. Now for the less good part. These fans are LOUD at the higher power levels. Trust me, it's louder than you probably think its gonna be if you crank it to 10, probably similar to a box fan running on HIGH, but you get quite a bit of airflow in return. I find maxing it out at 7 when the AC is on is tolerable tradeoff between cooling and noise. I really like the automatic modulation with AC status (monitored by the temp sensor in the duct). When the AC isn't running, I let it turn down to 5, which makes the noise barely noticeable across the room. One interesting aspect of installing these is that it inverts the temperature pattern in the room across the day. The room used to get hottest in the afternoon when it is hot outside, but now that is the coolest part of the day in the room because the AC runs non-stop and it only gets hot in the room in the middle of the night when the AC doesn't run much. Even limiting max power to 7, the room gets within 3F of HVAC setpoint during the day, and drifts to about 6F above setpoint at night with the 2 fans running at 5. I am very grateful for this device even with the noise issue, because the only reasonable alternative was to install a dedicated minisplit for the room, which would certainly be $10k+.
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Reviewed in the United States on June 18, 2026 by brandon mcclimon
Color: White
Size: 4” x 12”
I bought two of these a year ago to test in the main bedroom during the summer. Typically, the room ran at least 10 degrees hotter than the first floor of the house. The fans consistently kept the bedroom 1-3 degrees warmer than the first floor, it was noticeably cooler. It's now the second summer using the vents and the results are the same. I used to have to set my thermostat at 67-ish to have a shot at cooling the upstairs and eliminating humidity, especially for sleeping. Now, I leave the thermostat on 73 and if I find the bedroom a little warm, turn on an oscillating fan that's positioned by the vent. I'm a hot sleeper and with these vent fans and the oscillating fan, sometimes get so chilly that I have to grab a light blanket. The impact on the electric bill is also a plus. Temps reached over 100 degrees this summer but my electric bill didn't suffer. So, I bought another one this summer for the second bedroom. It is just as effective as the ones I bought last year. Installation is super easy--takes less than a minute. It looks fine. The controls and settings can be a little tricky but the instructions are pretty clear. App installation was easy and adding the new third register was easy--at first the app couldn't find it but the instructions including troubleshooting and that solved the problem.
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Reviewed in the United States on July 22, 2026 by N. Carter
Color: Bronze
Size: 4” x 10"
Our master bedroom is the furthest room from our central A/C. Due to the awkward layout of our cookie-cutter home, the lone vent that serves our bedroom snakes through 4 90s and transitions from sheet metal to flex, to sheet metal, and back to flex again as it goes through 2 separate floor cavities and up through a 2x6 interior wall. Long story short, it has never had adequate airflow to cool our room, especially during the 100°F+ dog days of summer. We already have a ceiling fan which does help, but it mostly just blows the warm air around the room. In the past, I've just run our central fan A LOT to continuously move air through the bedroom. Problem is, that means the central fan is always running circulating air through the whole house for the benefit of just 1 room. And running it all the time increases our power bill up by around $50/mo. Then I saw these vent boosters and thought "what if I used a 6 watt booster fan 24 hours per day instead of running our central fan almost all the time to see if it will achieve the same results?" Well I'm here to tell you, THE RESULTS ARE EVEN BETTER! I have the vent fan set to run full blast, 24 hours per day. And our room has stayed 8-10 degrees cooler than before, even through a record number of consecutive 100°F+ days this season. Since it keeps running when the A/C is not, it keeps pulling cool air through the cool evaporator coil even though the main fan is off. So the air it pulls through almost never even hits 70°F on the vent's thermostat. What's even better? Despite all those additional days of extreme heat this year, my power bill was about $50/mo less than previous years for the same months! So it paid for itself in a single month! So is it noisy? Yeah, a little, especially on the highest settings. But I can comfortably watch TV at a normal volume right next to it at a setting of 7 or lower. And since I sleep 5 feet from it, the Bluetooth app makes it really easy to adjust when we're in the room and need it a little quieter. We actually like the noise on high while we're sleeping, the white noise helps us sleep better. I leave it at a 10 at all times if I'm not trying to watch a show next to it. Conclusion: if it seems like this vent fan may be a good idea for a room that won't get cool or warm enough depending on the season due to an inefficient central air system, it is. Buy it today. You won't regret it. Sidenote, I'm in IT and I've used other AC Infinity products to cool expensive and important data equipment for a couple years now. They're all excellent. Better quality, quieter, and more useful features than units that cost 3X as much. This company knows what they're doing, and I can't sing their praises enough.
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Reviewed in the United States on September 2, 2024 by C. Wilson
Color: White
Size: 4” x 10"
Honestly, love this register booster fan. Want to give it a higher rating but order issues have made me want to give it less stars. Upgraded to these over a previous model for WiFi compatibility and control to make life easier. The only problem was just getting right one you ordered! I ordered 2 for our spare bedrooms, and the first time, I was sent a new in box and one that was clearly an open box. Had to get a replacement ordered. Shipping times are horrible also, but that’s not the end of the world. I finally get the replacement unit and it’s a completely different model generation. I ordered the one with the WiFi compatibility but received the one with only Bluetooth. They also have completely different displays and remotes! So I’m now having to return it again and order another replacement! Not sure if this is a supplier or Amazon issue, but it has been pretty frustrating. Now has been over a month long endeavor because of this and the long ship times. I do recommend it, it works great, just hopefully y’all don’t have the same issues I’ve had with just getting the right one you purchased. The fan is quite loud and may bother some people. We are a sound machine sleeping household so for us, it’s therapeutic lol.
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Reviewed in the United States on August 8, 2026 by Richard Day
Color: Bronze
Size: 4” x 12”
We live in an open loft. The primary bedroom is enclosed and on the 2nd floor with eastern exposure. It's always several degrees warmer than the open loft on the same floor. The ceiling fan helps but nothing compares to this vent! It dropped the temp 1-2 degrees(which is pretty impressive! )but there's also more airflow that feels cold instead of hot. I had very low expectations and am so pleased! We originally had it set to 8 but it was noisy. I imagine we'd get used to it but 5 is white noise and airflow is great.
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Reviewed in the United States on July 21, 2026 by D.Chen
Color: Bronze
Size: 4” x 10"
As stated in the title, our MBR (master bedroom) has wretched airflow. The geniuses who designed the homes in our neighborhood gave us pretty large master bedrooms (imo). But, despite putting multiple registers in significantly smaller rooms, one would be enough for the master bedroom. It's a common topic on the neighborhood FB in the summer, with more seasoned owners giving new owners all kinds of tips and hacks. I've tried combinations of all the hacks... but it's still ~10 degrees warmer and significantly more humid than the first floor. It usually gets even warmer since the exterior walls are on the SW corner of the home. Some have even decided (and we have considered) running central air in addition to adding a window AC to the MBR. tldr; the average temp in our MBR was a minimum of 10 degrees hotter. The day the AirTap T4 arrived, the thermostat was set to 71, and the room was 82. I set up the unit, pretty easy, but it might take some fiddling as the unit sits in your register and fits very snugly inside the vent. Sun was still out blasting the SW walls, but I showered, did a few chores, and came back and in 30 mins we were down to 79 degrees. Within a few hours we were down to 74, and for the first time it felt like the MBR was connected to the rest of the HVAC... I was impressed! A few caveats before I list my pros and cons... We have a Lennox iComfort system. Since the airflow is so horrible, one of the things I have set up is for the HVAC fan to run continuously starting in the afternoon. The hope is that the freezing air downstairs would mix with the hot air upstairs and even out the temperatures. It definitely helped, but there was still a pretty large differential upstairs, which means I would set the system to go down to (sometimes) as low as 66-67 at night to get some cool air upstairs so we could try and sleep. I've fiddled with every combination of adjustments to all the dampers and registers (even messing with returns). Pros: Easy to set up and install; made a big difference in temp between first story thermostat and second story MBR. After tuning settings to our liking, it's made a huge improvement, sometimes the room will be only a couple degrees higher than the first story. Since airflow has improved the humidity has greatly reduced, which also allowed me to increase the temp program on the smart thermostat. Cons: If you've never had a register booster, you might not know that they're pretty loud. I personally used to sleep with a "sleep sounds" app, playing rain, thunderstorms, wind, etc to drown out ambient noise... this replaces that. For me the steady hum helps me sleep, and the speed is adjustable between 1-10, thus impacting noise. Con 2: sometimes the temp sensor gets itself stuck in a loop, ie: HVAC turns off >> temp in duct increases near threshold >> fan ramps up and down as a result >> temp sensor goes up and down as a result >> now we're stuck in a loop for a little bit. So in future versions hopefully they put a delay on the temp sensor. Con 3: this is not a smart device, however, I would absolutely pay more for a smart version that would work with the smart HVAC, and/or work with other smart devices to control it.
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Reviewed in the United States on August 27, 2022 by MC