An inline fan is a great way to add extra circulation and humidity control where needed. The main benefit compared to a freestanding fan is that they integrate into the ductwork, meaning you can add them to existing infrastructure.
Of course, in these instances, you’ll want the quietest inline fans you can find. After all, there’s no point adding extra circulation if it means adding loads of noise too.
In this article, I look at the best inline fan for use around the home. I also provide a clear guide to help you make the best selection based on your needs.
Our Top 6
Where possible, I mention which are the best inline fans for particular setups, whether this is the kitchen, bathroom, or a grow tent. I base my picks on functionality, ease of use, and of course price.
1. Top Pick for Kitchen: AC Infinity RAXIAL 8” Inline Fan
- Airflow (CFM): 428 / (265) / (106)
- Noise (dBA): 43 / (35) / (28)
- Duct Size (Inch): 8 / (6) / (4)
- Speed Controller: Yes
(X): Other available models in the Raxial Series
This inline fan integrates easily into existing HVAC ductwork to improve air circulation. It’s particularly suited for kitchens because this 8″ inline fan has a CFM of 428. It can move air quickly, helping to remove steam and cooking smells with ease.
It has a noise level of 43dB, which is the equivalent of a quiet refrigerator. The manufacturer also produces 4” and 6” models that are quieter. Of course, these don’t move as much air.
This inline fan has a die-cast body and its rotating motion is supported by dual ball bearings. The bearings are designed so you can install the fan horizontally or vertically. Good bearings are essential for reduced vibration, longer lifespan and low noise levels.
It plugs into a standard wall outlet and has variable speed controls. This is useful in a kitchen because it gives you flexibility depending on what you’re doing.
Some users noted that the fan doesn’t do well with restrictions to the airflow, such as a carbon filter or flexible ducting. This is mainly why it’s better suited for a kitchen than, say, a grow room or bathroom.
- Noise level of 43dB.
- Available in 3 sizes.
- Die-cast housing increases durability
- Doesn’t do well with airflow resistance.
2. Top Pick for Bathroom: Nutone ILFK2502 Inline Fan
- Airflow (CFM): 250
- Noise (dBA): Not Communicated
- Duct Size (Inch): 6
- Speed Controller: No
This fan is one of the best inline fans for a bathroom because it comes with an installation kit. Importantly, this means you can easily integrate it into your HVAC system to replace your current bathroom fan.
The kit includes grilles, sleeves, and an adapter along with a 6″ inline fan. Overall, this makes it pretty easy to install.
Even though it’s a 6″ inline fan, it’s rated at 250 CFM and so is suitable for bathrooms up to 215 sq. ft. Also, it’s Energy Star certified, meaning it won’t use much energy even when running for long periods.
Much like a standard bathroom fan, you control it using a wall switch. Bear in mind, this means you’ll need to do a bit more wiring. But it’s obviously more convenient, as most bathrooms don’t have wall outlets.
While users reported the inline fan to be very quiet, some did note the spring clips included aren’t great. Consider buying some recessed lighting spring clips instead or simply gluing the fan in place.
- 250 CFM – suitable for large bathrooms.
- Easily replaces standard bathroom fans.
- Energy Star certified.
- Includes installation kit.
- Spring clips aren’t great.
- We’ve seen better build quality
3. Top Pick for Grow Tent: AC Infinity CLOUDLINE T4 Inline Fan
- Airflow (CFM): 205 / (402) / (807)
- Noise (dBA): 28 / (32) / (39)
- Duct Size (Inch): 4 / (6) / (8)
- Speed Controller: Yes
(X): Other available models in the Cloudline Series
I recommend this quiet inline fan for growing setups because it also includes a heater. This is helpful if your plants need warmer temperatures to grow properly. Of course, you must balance this against higher energy usage.
This 4″ inline fan is quiet and has a CFM rating of 205. You might find this too strong for smaller grow tents, but it has an 8-speed control for just this reason.
But, if you want even greater airflow, you can easily set 2 inline fans up in series or parallel. You can get a total CFM of 804 by setting it up with other models of the Cloudline series. The controller is very user-friendly to control all of them together.
What’s more, this inline duct fan has a noise level of 28dB, which is very quiet. More powerful models of the Cloudline series can reach 32 dB, delivering up to 402 CFM.
It also includes features like power cycle memory for retaining settings and humidity control. If you want a basic and more budget-friendly model without these features, consider the S4 from the same manufacturer.
Some users reported issues with the humidity sensitivity, saying it was at least 20% higher than what the fan registered. If humidity is important for your grow, consider a separate sensor just to double-check readings.
- Noise level of 28dB but still good airflow.
- Inline fans can be linked up for better circulation.
- Includes temperature and humidity controls.
- Humidity sensor accuracy could be better.
4. Top Budget Pick: VIVOSUN 4-Inch Inline Fan
- Airflow (CFM): 195
- Noise (dBA): 30
- Duct Size (Inch): 4
- Speed Controller: In option
While this quiet inline fan is a budget-friendly option, it sacrifices very little in the way of quality. Importantly, it has an airflow of 195 CFM at 2500 RPM, and a noise level of 30dB.
It features an air deflector, which unsurprisingly directs the flow of air through the inline duct fan. While the manufacturers claim this reduces noise, it seems little more than a marketing gimmick. The RAXIAL fan mentioned above has a CFM of 265 and a noise level of 35dB without deflector.
You can use this inline fan in pretty much any application that’ll take a 4″ fan. You might find that bathrooms and kitchens have larger ductwork, meaning you’d need an adapter to fit it properly.
One way VIVOSUN saves money on this model is by selling the speed controller separately. Luckily, it’s not very expensive but is worth buying if you want to adjust the fan’s speed. Using it with the fan provides 4 speed settings
This small inline fan plugs into a wall outlet rather than wiring into a wall switch. While this is fine for kitchens and grow tents, you might want a different model for a bathroom.
Some users reported the fan’s housing is a bit flimsy, which contributes to the noise level. But, you can get a free exchange if this happens in the first 30 days and it seems to not be a universal issue. So, if your inline fan starts making noise, replace it if possible.
- Noise level of 30dB.
- Airflow of 195 CFM.
- Suitable for various applications.
- Max speed of 2500 RPM.
- Speed controller sold separately.
- Air deflector doesn’t appear reduce noise
5. Terrabloom 10” Inline Duct Fan
- Airflow (CFM): 1065
- Noise (dBA): 65
- Duct Size (Inch): 10
- Speed Controller: Yes
If you need a powerful grow room exhaust fan, this might be the model for you. It boasts an impressive airflow of 1065 CFM. But, this is offset against its maximum noise level of 65db. This makes it the most powerful and loudest fan on this list.
The AC Infinity fan above would be fine for a small grow tent, but you’d want an inline duct fan like this if you’re ventilating a whole room. It can provide either intake or exhaust depending on the setup and is easy to fit into ductwork.
It comes with a speed dial and optional wireless remote. The included dial gives you great flexibility over fan speed, as you’re not limited to preset functions. You can also upgrade it with a temperature control and digital speed controller.
Although this is suggested as a grow room fan, nothing is stopping you from using it in other applications. You might find this difficult unless you’re installing specific ducting, as 10” is quite big.
The only real issue users reported is that the fan is noisy when operating at full speed. But, the same users reported it provides enough airflow at ¾ speed, which also drastically reduces noise.
- Ideal for grow rooms.
- Powerful airflow of 1065 CFM.
- Plenty of optional extras.
- Maximum noise level of 65dB is high compared to its competitors
6. VIVOSUN 6-Inch Inline Fan with Carbon Filter
- Airflow (CFM): 390
- Noise (dBA): 37
- Duct Size (Inch): 6
- Speed Controller: Yes
This is another good quiet exhaust fan for a grow room because it includes all the necessary pieces. You get the fan, a carbon filter, humidity sensor, and 8 ft. of ducting.
The inline duct fan has an airflow of 390 CFM, which will be fine for smaller grow setups. Importantly, the 6″ inline fan is quiet, with a noise level rating of 37dB.
Inside the carbon filter is RC-48 carbon. This is a particular type of carbon found in Australia and is very effective at removing contaminants and odors from the air. It’s ideal for certain grow setups where odor control is important.
Setup is fairly easy with all the included components. It’s all designed to fit together, meaning you don’t need to worry about choosing the right ducting. The set comes with clear installation instructions.
Some users reported issues with the fan’s speed control, saying it made very little difference. If you’re working with a small grow setup, your only workaround is to buy a smaller fan with a lower CFM rating.
- Strong airflow of 390 CFM.
- Includes carbon filter and other equipment.
- Easy to set up.
- Inline duct fan is too strong for smaller grow tents.
Typical Setup of Inline Fans
Buying a quiet inline duct fan is one thing, but the setup is just as important for noise levels.
The typical setup for kitchens and bathrooms will probably involve adding an inline duct fan into your existing HVAC setup. It can help improve air circulation and means you don’t need completely new ducting.
But, you might find that installing a small inline duct fan separately from your main HVAC system does just as good a job. If you do this, you’ll need new ducting.
While it might not look great this way, you’ll probably have more control over noise levels because you can choose ducting and direct it how you want.
Whatever room you’re setting up in, make sure you check its size first to get the right CFM rating. Along with this, here are some quick tips for setting up silent inline fans.
For Rooms
Use flexible ducting, as it has better sound deadening properties than rigid ducting.
Choose an inline duct fan with a higher CFM rating than you need. This allows you to run it at a lower speed with the same results, which means less noise.
Fit a backdraft damper to reduce noise and retain airflow.
Importantly, make sure all ducting and accessories are the right diameter. Making them fit will reduce efficiency, which could impact noise levels.
For Grow Rooms
A grow tent or grow room won’t require a vastly different setup other than adding filters.
PWM motors are usually the quietest, as are brushless motors.
Again, opt for an inline duct fan more powerful than you need. AC Infinity recommends adding an extra 25% on, particularly if using a carbon filter.
Insulating ducting can control moisture levels, which can affect the inline duct fan and make it louder, or break it.
Suspend ducting and fans from the ceiling to reduce vibration transmission through solid surfaces.
Consider soundproofing the tent or grow room as a way of reducing noise levels from the working components.
How to Pick the Right Model for You
When selecting a quiet inline duct fan, you need to think about more than just noise level. Be sure to consider these factors:
CFM Rating
CFM stands for Cubic Feet per Minute and is a rating of how much air the fan moves. As this is a fan’s main job, it’s obviously an important factor.
CFM does relate to room size, but this is less important when thinking about applications like a grow tent. Most inline duct fans will be more than enough for a small tent. But, as I mentioned above, you want to add an extra 25% onto your needs.
To work out the right CFM, you first need to know the volume of your space in cubic feet. This is the length times width times height. For example, a tent that’s 4’ x 3’ x 6’ has a volume of 72 cubic feet. You’d need an inline fan with a CFM rating of at least 72.
Always consider choosing a model 20% above your baseline need. It will account for the loss of pressure induced by the turns and length of your ducting.
If you have grow room accessories like a silencer or a carbon filter, it will reduce the inline fan’s performance. I discuss this in more detail in the final section of this article.
Generally, larger inline fans will have a higher CFM rating. Most manufacturers will state it, so check this before buying.
Variable Speed
Variable speed is useful for quiet inline fans because it impacts the noise level. Fans operating at a higher RPM will produce more noise than at a lower speed.
Speed is also tied to CFM, as faster speeds usually mean more airflow, although this also relates to the fan’s size.
If the inline fan’s CFM is right for your needs, you don’t need variable speed. But, opting for a variable-speed fan with a higher CFM allows you to operate it at lower speeds. This means less noise, even with quiet models.
The controller might be a remote or a dial. A dial will give you greater flexibility than preset speeds, but either works fine.
Noise Level
A typical domestic inline fan can have an operating noise level of up to 70dB. This is the equivalent of a noisy restaurant. So, it’s not painfully loud but would be annoying if you’re dealing with it constantly.
Acceptable noise levels for the quietest inline fans are subjective. But, I’d recommend looking for ones around the 35-45dB level. This is around the same level as a refrigerator, so shouldn’t be too distracting.
The important things to look out for when picking a quiet model are:
- Die-cast or unibody housing – reduces vibration.
- Lubricated ball bearings.
- Low noise level ratings on the product specification
- High quality parts (metal fan blades, EM/brushless motor). This will usually be reflected in the price.
Interestingly, inline fans are ducted, which means the fans are not directly in contact with open air. The ducting helps to reduce the vortices generated by the blade tip. As a result, it helps in reducing noise compared to, say, an open-air fan. I discuss this in more detail in my article about quiet drones in the Propeller section.
Any manufacturer touting their fan as quiet will state the decibel level. Look out for this and compare it against a chart of common sounds for a better understanding.
Installation Compatibility
When installing a quiet inline fan, you should ensure it matches the other equipment you have. It isn’t a massive problem if you’re buying ducting but can be if you’re integrating it into an existing setup.
Silent inline fans come in a few sizes: 4”, 6”, or 8”. You can get 10” and 12” too, but these are less common.
The fan’s diameter is tied to factors like CFM rating, noise level, and to a lesser extent energy consumption.
Whatever size you pick, just make sure everything else matches it. For example, ducting and carbon filters must be the same diameter. If they’re not, you’ll have a difficult job of making them fit.
When setting up a grow tent, it makes sense to buy a complete kit if you can find one. It simply takes away the problems of finding compatible hardware.
Temperature and Humidity Control
These extras aren’t that important for somewhere like a kitchen but might be helpful in a bathroom. Generally, you’ll want temperature and humidity control on a grow room exhaust fan.
They’ll obviously increase energy consumption but should have little or no impact on noise level. If choosing a model with these extras, make sure it comes with clear control modules. Digital is best if you need high accuracy.
Accessories to Consider
The accessories listed below are probably most applicable for grow setups. Granted, you could use them in your kitchen, but there’s not a massive need for a carbon filter in that setup.
Silencer
An inline fan silencer works exactly the same as a car exhaust muffler. You fit the fan into it, and the chamber absorbs or disrupts sound waves as they pass through it.
Even when buying a quiet inline fan, a silencer might be a good idea. A silencer adds roughly 20% to your required CFM rating.
Carbon Filter
A carbon filter uses its large surface area to absorb odor molecules from the air. While it also works against other airborne particles, this is its main application in a grow setup.
Other than getting the right size filter, you need to consider carbon type, mesh size, and how the filter works with your fan’s CFM rating. A carb filter increases the necessary CFM rating by up to 60%.
I recommend watching this video for more details.
Lighting Rigs
Considering we’re talking about silent inline fans, lights aren’t that important. You must factor heat emissions from lighting into your overall CFM rating, though.
The AC Infinity article above suggests adding 50% extra to your CFM rating if using LED lights, for example.
Final Thoughts
Hopefully, you’ve now got some useful information for choosing the best inline fans for your needs.
My top picks vary by room or setup, but they all offer decent CFM, low noise levels, and easy installation.
If you’re on a tight budget, the VIVOSUN 4-Inch Inline Fan is suitable for any application. Its CFM might not be massive, but it’ll still operate well.
If you’re looking for quiet ways to ventilate a bedroom, check this resource about quiet bedroom ceiling fans.
Do you have any other suggestions for the best inline fan? Let me know in the comments below.
