Fan recommendations

coreywebster said:

Box fans are pretty quiet, I have a airforce 2 silent acoustic fan(not a box fan), its quality but not as quiet as desired, partially due to a built in speed controller which made it hum on low speeds. The fan is rated at 55db which is not quiet in my opinion. Same fan has multiple names depending on where you are in the world. Hyper stealth, isomax, and various other names, all seem to be the same, basically a good inline fan build inside a silencer. But that is just acoustic foam in reality. It makes it sound quieter from the side but sound goes through the ducting.

From what I have seen of box fans they can be rated as low as 30db, a friend owns one and its damn quiet.

The best thing to do is oversize everything and use a proper speed controller which steps the voltage down like a variac . Runnig a higher power fan on low speed can be really quiet. You can box any inline fan in using mass like mdf and fill the box with acoustic rockwool. Oversize the ducting and use acoustic ducting. Oversize the filter so same air is passing through a larger area and thus quieter. Don't buy any fan with built in speed control because most cause a hum, that hum is more noticeable to some people than others. But its a frequency that's harder to stop than the sound of air moving.

If your in an attic you could hang it with bungie cord after its been boxed in to limit vibration.

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