If you’re looking to reduce the noise from exhaust fans in your grow tent or grow room, it is important that your inline fan doesn’t run at full speed.
We’ll show you several options of fan controllers that can help you run fans at lower speeds to reduce noise and vibration. We’ll help you choose the best fan controller for your needs and budget.
Fan speed controllers
Fan controllers allow you to run fans at less than full speed, which greatly reduces vibration, the noise of the motor, as well as noise from air movement. Most inline fans used for marijuana growing don’t have different run speeds as would be seen in household window fans. Fan controllers can resolve this.
There are three types of fan controllers commonly used in grow rooms:
- Solid state fan speed conrollers
- Variable autotransformer (Variac) fan controllers
- Variable Frequency Drives (VFD, AFD)
Solid state fan speed controllers
Solid state fan speed controllers are inexpensive, costing around $20. They’re very popular because they’re cheap, but in the long run they’re not a great choice. Solid state fan controllers cause the fan motor to hum due to how they function, and can lead to premature fan motor failure.
They’re not compatible with all fans either, so in general it’s not recommended to use them. But since initial cost is often a grower’s biggest consideration, if you do choose a solid state controller you need to make sure that it will work with your setup. But know that you’re not choosing the best fan controller for growing marijuana.
Variable autotransformer (Variac) fan controllers
Variable autotransformer fan controllers are a much better choice than solid state units. They don’t produce fan hum since they provide a continuous sine wave of a lower voltage. This means they won’t risk damaging your fan like solid state controllers might.
Variac controllers are the best fan controller for growers on a budget. Prices start in the $60 range. Make sure to buy a unit with amp ratings that are well above the amp requirements for what you plan to run, and remember that when fans turned on there is a power surge so you’ll need to ensure the amp rating on your variable autotransformer is high enough for the fan you plan to run.
The amp ratings are more of a concern for growers running multiple fans through the controller. Most 6 inch or 8 inch fans will be rated at under 1.5 amps and would have no problem running on a 3 amp 120 volt variable autotransformer.
Variable Frequency Drives (VFD, AFD)
Variable frequency drives (VFD) are the best fan controller for growing marijuana in terms of how they operate. In a perfect world if price isn’t a consideration you should go with this option.
The circuitry in VFD controllers sense changes in the motor, which allows it to adjust the frequency and voltage of the AC source. This maintains a constant tourque, something that voltage regulation (which is used in the solid state and variac options listed above) cannot provide.
But variable frequency drives are expensive at several hundred dollars, so they’re not the best choice for people with limited budgets to outfit their grow rooms. Most growers could purchase both a fan and a variable autotransformer for less money than a VFD.
If it’s important for you to have the best fan controller to quiet exhaust fans in marijuana grow tents, then choose variable frequency drive. If you’re looking for the best combination of performance and price, you should choose variable autotransformer. If you’re just looking to spend as little as possible and can accept the tradeoffs of motor hum and potentially ruining your exhaust fan, the solid state is an option.
Overall, we recommend variable autotransformer fan controllers. We’ve used two and have found them to be a big help in reducing the noise in marijuana grow tent/room setups.