Growing indoors requires three primary investments: a grow tent, grow lights and an exhaust system. While grow tents and LED grow lights get all the attention, the inline exhaust component often gets ignored. Perhaps grow tent fans aren’t as flashy as LED grow lights, but we’d argue they are just as important. If you are setting up a new grow room or revamping an old one, it’s time to look at the newest in grow room fan technology.
Like we battled LED Grow Lights in 2021, we are now turning our attention to a Grow Tent Inline Fan Battle.
Are Inline Duct Fans Loud?
Inline fans are mounted in the building’s ductwork, so they are generally kept away from working and living spaces.
Like all fans, their noise level depends on many factors. Large fans are noisier than smaller ones. Fans mounted in attics or separate spaces will likely never be heard at all.
Just like quiet desktop fans, inline blower fans vary considerably in terms of quality and construction. The best ones are quiet enough to use in small rooms, while less expensive and noisier options are best left to greenhouses and outdoor situations.
How Do I Setup the Quietest Inline Fan?
There are a few tricks you can use to quiet down a noisy fan.
Your first step, though, should be to make sure that there’s nothing wrong with the fan itself. All fans have bearings inside the motors, and over time friction can wear at these parts, causing excess movement and noisy vibrations.
If the fan itself is loud, it’s time to upgrade to a new, high-quality energy-efficient system with a duct booster.
Install Your Inline Fan for Quiet Operation
If you’re sure that the fan is operating as quietly as possible, the next step is to make sure that your installation is sound. If the fan is allowed to vibrate, this noise will reverberate in the ducting and sound even louder.
Use Anti-Vibration Mounts
If your fan didn’t come with them to start with, you could purchase anti-vibration mounts that absorb some of the sounds. They’re little rubber feet that attach where you’ve mounted your fan.
Some people even hang their fans with a bungee cord to allow them to hang freely from the walls or ceilings. This way, the sound isn’t transmitted into the building.
The final trick is to reduce the rate of the fan. It’s noisiest operating at full power, so if you can reduce that even partially, you’ll likely get a significantly more silent system.
If you need more air moved, consider upgrading to a larger fan that you can operate slower.
Add Soundproofing
Finally, if your inline fan is mounted in an attic space, look into soundproofing your ceiling to hide all of the HVAC noises, including sounds from your fan.
If your fan is mounted outside your room, you might also look into ways to soundproof your windows.
If you’re off the grid and running your fan off a generator, knock the generator noise down slightly with these tips.
DL Wholesale 8” F5 In-Line Fan w/ Silencer
Features:
The ultra-powerful F5 Fans use advanced mix-flow technology and have a specially engineered aerodynamic design which allows them to achieve an unheard of level of performance and efficiency. These fans maintain high CFM ratings, have powerful internal drive motors, are aerodynamically designed, feature UL recognized components, and an attached 8 ft power cord and mounting brackets. F5 explosion proof portable exhaust fans are optimal for use in flammable or explosive environments where quality air circulation and exhaust ventilation is needed. This model features built in silencer walls to ensure the upmost in privacy as well as less general noise in your growing environment.
Vortex S-800 711 CFM 8" Inline Fan
Features:
The Vortex inline fan is a revolutionary series of fans that combine energy efficiency, ultra-quiet operations and a collection of advanced technologies that deliver unparalleled performances. An extremely energy efficient ac brushless motor powers the patented mixed-flow dual impellers. Built with double insulated walls, noise is reduced to levels that were previously thought to be unattainable. S-Line Mixed Flow Fans are designed for residential and light commercial ventilation applications. These compact, powerful, and quiet fans are available in 6 in., 8 in. and 10 in. duct diameters and are ideally suited for either supply or exhaust ventilation systems. The fan and motor are precisely balanced for a quiet and vibration-free operation.
Buying guide
Air volume
Probably the single most important aspect of an inline vent fan is the airflow generated, which is given in cubic feet per minute (CFM). Depending on the installation, you might need to move a set amount of air continuously or completely replace the volume of a room in a given time period, once an hour, for example.
Some calculations are straightforward. If you have a 144-square-foot room with a ceiling height of 8 feet, that’s 1,152 cubic feet. Experts recommend adding a 30% margin, making a total of 1,497.6. So if you want to change the air once a minute (admittedly pretty extreme), you’d need a 1,500 CFM fan. If you wanted to change it six times an hour, you’d need a 150 CFM fan.
Each situation is different. For instance, if you add air filtration, you’ll probably have to increase the airflow to compensate for the restriction the filter can cause. You’ll either need to research your specific situation (there is a lot of valuable advice online about setting up grow rooms, for example) or consult a specialist. It’s vital that you take your time over this aspect. If the cubic feet per minute are wrong, the fan won’t provide the results you need.
Size
Physical size is important both in terms of the space where you have to fit it and the diameter of ductwork it’s connected to. Most inline vent fans are specified by this diameter. The smallest are generally 4 inches, and it’s unusual to see them larger than 12 inches.
External dimensions are equally important. Household models and most grow room fans have motors that are mounted within the unit and so remain relatively compact. Industrial vent fans might have a belt drive from a motor mounted on the outer casing.
Controls
Many inline vent fans require minimal control. They are either always on, activated by some kind of manual on/off switch, or start and stop automatically, when linked to a heating, ventilating, and air conditioning (HVAC) system, for example.
Others offer further options, such as different speeds (up to ten) adjusted via a handheld or wall-mounted controller. Advanced inline vent fans have sensors and can be set to activate automatically at given temperatures or humidity. They can also have timers, as well as alarms if certain conditions are exceeded.
Materials
Body: The materials the inline vent fan is made of may need to be considered, too. Most cheap models have a galvanized steel body to prevent rust, but they aren’t really designed to be used in damp environments. For that kind of application, a ceramic coating provides better protection, and a sealed motor is often offered. There are also models designed for use where extreme heat might be a problem, or where there’s the potential for a fire hazard.
Blades: Another feature of low-cost fans is a plastic impeller (fan blade), whereas metal gives improved durability.
Mount
You also want to think about how the fan will be mounted. Brackets of some kind are usually built-in, but they may need to be adapted. Although some fans are light, it’s not a good idea to fit them into flexible ducting without some form of support.
Noise
Noise is an issue in some cases. It can be given as either decibels or sones. A sone is quieter than a whisper. Four sones don’t seem like a big number, but that’s an inline vent fan that’s as loud as a motorcycle! On the other hand, quality models can be so quiet you won’t normally hear them.
Power
The power requirement in the majority of cases is the standard 110/120 volts. Many simply plug into a standard household outlet (you should probably check the cord length). Others, particularly those with high-end control functions, require special wiring. When you’re thinking about costs, you might need to consider the services of an electrician.
Maintenance
Maintenance is seldom necessary for household situations, but regular cleaning is frequently needed where there are airborne contaminants like grease from commercial kitchens or dust from industrial processes. In these cases, it’s a good idea to look for models with sealed bearings, which prevents them from excessive wear (they’re usually quieter, too). Seals might also be used to prevent dust or liquid ingress, providing further protection for your fan.
If the fan motor is fitted with an older-style brush motor, then eventually the brushes will need to be replaced (though it could be several years). Modern brushless motors are maintenance-free, but they do add to the cost.
Conclusion
Inline fans are handy items that can be used for an astounding number of purposes. While many are marketed towards gardeners and nursery owners, you can also use them in homes and various HVAC systems. Plus, they can make a good booster fan when you need more airflow from an existing system.
But no matter where you’re putting it, you want to find the quietest inline fan you can get.