Preventing noise travel from a hanging inline fan

[Schmokey]

I’ve got it hung and I think it’s going to be ok. That said, I just fired it up and even on low speed it’s loud enough to want to do something with it. No vibration noise traveling up through the house, so that’s a win.

However, with that gaping inlet just sitting up there itching to swallow something, chew it up and spit it through, boxing it in is definitely on the to do list (at the tail end of the honey-do list), complete with filter to save on cleaning.

Those are 3" lag bolts going up into the joist. Should be good for about 200 lbs, so no worries of them pulling out.

This is grow room revision B. I had another room in the basement pretty much completed and decided this past weekend to blow it up and move into a more suitable part of the basement. The prior room had no windows and no access to outside. This room, (prior to putting up a partition wall) had two windows, one in what is to be the flower room and one in the room where this fan is which will be a veg/propagation/mechanical room and contain the carbon scrubber, aero-cloner, pumps and anything else that isn’t a plant in flower.

The best part of it all is I have my wife on-board with this. She is a flower freak and wants to propagate ornamental plants. With me being the kind sharing husband that I am, and willing to provide space for her needs I can justify almost anything. It’s going to take some time, but this is should be a pretty sweet setup for a home grower when I get it up and running.

[ReikoX]

@Schmokey

However, with that gaping inlet just sitting up there itching to swallow something, chew it up and spit it through, boxing it in is definitely on the to do list (at the tail end of the honey-do list)

Yeah there are two sounds a fan will make. The vibration or motor noise seems to be taken care of with the bungee cords. Now you have the sound of the air moving, I suggest a duct silencer. I made one for my 4" fan and it helps muffle the whooshing sound.

[Muleskinner]

without a carbon filter strapped on the end that fan is going to sound like a jet engine on full power, you could probably suppress most of the noise with a few feet of duct tube with a few layers of AC foam over the opening.

You can buy sheets of air conditioner foam prefilter at the hardware store for cheap. It will keep the fan blades clean too.

[Schmokey]

For shit’s n’ giggles, I just took sound level readings. Readings are taken with an app on my phone. While probably not relevant to anyone else in the world, they’ll give me a baseline to work with as I make changes.

Readings noted are LAF measurements. With the fan off, furnace off (it’s in the next room) the ambient sound level is about 28 dBA. With the fan running on low speed sound level is 58 dBA and at highest speed the reading is 64 - 65 dBA.

First order of business will be to get the intake of the fan dealt with, even if it’s only a chunk of screen. Safety first and all that. Plan is to box the fan in and get a filter happening somehow.

@Muleskinner - This fan is for light cooling only. Carbon scrubber is a project for another day and will use a separate multi-speed fan.

[Explorer]

@Schmokey

With the fan running on low speed sound level is 58 dBA and at highest speed the reading is 64 - 65 dBA

Does not surprise me. Standing near my 6” fan I have to pop my ears after leaving a room to hear again and that’s just a 500CFM fan louder than a vacuum cleaner IMHO and my fan is supposed to be “silent”

[spaceman]

That looks great. Man I wish I had room for a room.

Be careful with wives and ornamentals.
My wife potted up her flower seeds using burpee mix straight out of the bag and I still have fungus gnats to deal with.

But back to the topic: fluid mechanics or what I know about them, suggest that the coils of that flexi vent pipe interfere with airflow causing turbulence, noise and reduced efficiency.
I use them too.
Any one know of a flex pipe that is smooth on the interior?

[Schmokey]

@spaceman

Be careful with wives and ornamentals.

Any new ornamentals will be kept in another part of the house until we’re double sure they’re clean. She’s into propagating for resale and has good reason to ensure everything stays clean. I wish I could say the same for the orphans she keeps dragging home. We just finished paying $3g’s to have the entire yard re-sodded and I’ll be damned if she’s not out there digging phucking holes everywhere for these things she just can’t not drag home. We have this long standing battle over the meaning of the word weed. By definition, a weed is any plant that is objectionable where it is growing. Hence, I keep trying to tell her that if it’s not something I can eat or smoke, it’s a weed and should be treated accordingly. Put the mower to it and be done with it.

As you say, back on topic -

I went with an 8" fan for two reasons. One is to ensure that I have well more air pushing capacity than I need, and the second is the ability to run the fan at lower than rated capacity to help keep the noise down. I have no illusions about having a quiet system. As I said in an earlier post, I have this aversion to vibration type noise traveling through the house since it’s largely avoidable.

In all of my years working in HVAC I’ve never seen flex duct with a smooth interior. Can’t see how that would be possible. About the closest you’ll find is flex that has sound deadening material on the inside, but even that is going to cause restriction.

@spaceman

That looks great. Man I wish I had room for a room.

Thanks. Building a dedicated indoor grow room is a lot of work, and my work is long way from being done. As in months. I’ve spent an awful lot time considering the tent(s) option, and I’m still not convinced a dedicated grow room setup is “the” way to go.

[spaceman]

@Schmokey

she just can’t not drag home.

lol
Same goes for volunteers, esp. oak tree volunteers.
I have seven now in pots, that I’ve liberated from other parts of my yard.
Finally, thinning as in “scatter seed over prepared ground, thin to 3? inch centers”.
Not to sound too extreme here but THINNING IS MURDER.
Not just to the plant but to all my nonexistent spare time.
Ever thin a bed of carrots?

She sounds like a keeper. And definitely you have a plan. That too is a keeper.

In all of my years working in HVAC I’ve never seen flex duct with a smooth interior

Eventually I’ll move on to galvanized with taped joints. With my neverending home remodel ongoing, I have to pick my battles.

Good luck!

[beacher]

Insulated ducting can really help. You could put a few feet on the open end to cut the sucking sound and prevent arm choppage lol

[Schmokey]

For the time being I’m just going to hang a short chunk of flex off the intake side with a screen over the open end. At least it won’t eat anything. Eventually I’ll box it in and get a proper filter on it, but at the moment I’m too busy getting some light happening. I’ve had 4 auto’s from that crap seed from last year sitting in bags on the floor with next to no light for almost a week now.