LEDgardener

Bought 4x2x7 tent. Need exhaust fan recommendations. Quiet is the main thing that I am after. AC Infinity Cloudline S4 is one that I am looking at. My tent would need 75 CFM, 100 CFM with filter. This fan is rated at 205 CFM and comes with manual controller utilizing PWM. In theory running at 50% should do me. The thing that worries me is I have tried to quiet PC fans using PWM and the noise they made was worse than just running them full blast.

Any experience with these fans or other recommendations?

Would getting a 6” and running even slower be better?

Also I want to mount fan at bottom of tent to suck warmer air from ceiling, any problems with this idea?

I’m running a Vivosun 4” 110cfm fan from Amazon in 4x4 tent. It’s very quiet but I have read reviews of people complaining about noise, so maybe I got lucky and got a quiet one. I would think their 6” fan would be just as quiet. You might have to try a few different fans to decide what’s too loud for your liking.

I’ve seen some fans w/pwm control and didn’t notice any extra noise because of the controller. I’m guessing that if you’re doing pwm control you are automating the fan? You could buy a fan from Amazon with a speed controller built into it. Not pwm, more of just a potentiometer type control.

As for where you mount the fan isn’t really relevant but should have any type of filter mounted as close to the fan as possible. So if you are wanting to vent heat, it would be best to mount the fan and filter at the top of the tent. But having a few feet of ducting between fan and filter isn’t the end of the world, but could cause a small loss of efficiency.

Remember that you will also need to think about fresh air intake. If you remove 110cfm of air, it needs to be replaced with fresh intake air. Some people choose to use a second fan to force air into the tent and try to balance cfm intake to cfm outlet.

Good luck and happy growing.

Cheers
YYC

Sure get the biggest size stuff you can get. A bigger fan doing 100cfm is more quiet than a small one pushing 100cfm at max.

A muffler and insulated ducting are great

if you had to choose between a "Super Quiet" $$$ fan with regular ducts or a normal fan with insulated ducts and muffler, go with the muffler and ducts. Beware that some insulated ducting has tiny holes so it must be used wisely

edit: not sure, if it's an EC fan you can dim without hum/noise

edit: Warm air travels up - surely any heat from leds in a 2*4 will not reach the ground. if you want to put the fan at the bottom to suck warm air that means you will be adding a long inlet duct with a bend. Every bend and every length of ducting reduces your CFM. The filter itself also causes a significant reduction.
There's no problem with your idea if you account for those losses

(The best fan to put at the bottom is a box fan, they are also most quiet)

Go to home depot and look up the sones that each bathroom fan produces. Can get some down less than 2 stones for relatively cheap, comparable in price sometimes cheaper.