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How To: Hang a big fan & filter

f-e

Well-known member
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There are many ways to hang a filter. This is mine.

First, I lay my filter, fan and any acoustic dampeners on the floor. I use anything available to sit them upon, in order to line up the connections. Gaffer tape them, then fast-clamp. This gets my entire assembly together on the floor.

I then lay a beam of wood along the top of all my stuff, and tie everything to it. Rope for the filter, and string for the bits that don't weigh a lot. Now I have everything tied to my beam (often a 2x2) that can be lifted and suspended as one unit.

What you are going to tie it too depends on the building structure. In the pic, I have used some strong wall brackets. You may wish to drill the roof beams from above to use long eye bolts. Me, I like to make a strong net frame for the plants, that reaches the roof. So it's all free standing, with no fixtures to the building at all.

So, you have your fixing points at high level, and all your stuff on a beam. Time for the rope ratchets. Just like you may hang lights with, these come in a few sizes, right up to Articulated vehicle straps. The filter sized ones should do. Using one each end, you can slowly raise the assembly, one end at a time, all on your own. Presuming you can take the filters weight while you pull up a few clicks on the ratchet.


Take it up to just a couple of inches lower than you want it, and use some proper rope to secure it. Now it's time to stop it shaking the building. In the pic, you can see some blue lines. It's elastic. You want some elastic that's too thin to work with one loop. 5mm bungie cord perhaps. You put a turn around your beam, and high level fixing point, pulling the cord as you do, so it's at maybe 30% of it's possible extension. If the cord was thin enough, it won't do anything. It should take a few turns before the beam starts to be lifted by the elastic cord. You can pull a bit of slack between the turns as fine tuning, which is why you want a few turns.

When the elastic is right, the whole thing can bounce. You can both push it up with a finger, or pull it down with a finger. Because there is no solid connection to the building structure.


Acoustic dampeners/mufflers/silencers, whatever, are good. Most of their work is done within the first 40cm. Equally, hard pipe is good. A short length of solid ducting can reduce the noise a lot. Just 40cm between fan and filter can make a big difference to the noise coming out the filter. On the exhaust side of the fan, you could line a tube with camping mat to further reduce noise reflections. But just pipe is surprisingly good. While a full on 600mm 'real deal' is really quite good.


As a closing note, fixing to the roof may use it as a sound board, amplifying noise. If the walls are brick/block construction they are much harder to shake(impossible though a bit of elastic). However, if using the wall bracket approach, don't fix to the top block of a wall that goes no higher, and then put the weight at the very end of the bracket(as in the pic). You could lever the block out. Just keep your weight near the wall, pulling the block down in place.
 
N

Newguy420

Excellent post f-e and just what I was looking for. Putting the filter fan Ducting on floor the lift
With wood as one unit I am doing that.
Appreciate the post thank you
 

SuperBadGrower

Active member
Great post! I think this rubber is made for the job?
834.jpg
 

f-e

Well-known member
Mentor
Veteran
The real key to this, is that it can bounce easily. Meaning non of the rubber is near it's limits of extension/contraction. If an imbalanced blade set wants to oscillate the entire hanging mass, it can. You won't see it, but its happy to circle about. However these partially stretched low modulous bands can't transmit the vibration, any more than they can stop that fan moving about.


Another approach entirely, where fans and filters are sat on the floor, is apposing weight. Large machines planted upon rooftops sit on springs, upon huge concrete blocks. The small vibration that gets through the spring, isn't enough to shake the huge block. So a stack of paving slabs can stop a floor from moving, when the fan&filter assembly sits upon them. This is why I don't attach to ceilings with a loft space above, and would choose the wall or a heavily laden floor for my building contact points
 
N

Newguy420

Does silencers work on 8ins rvk fans to help
With the noise of air moving
 

Lester Beans

Frequent Flyer
Veteran
Gas tank straps. They are flexible, can handle the weight, and have some rubber to them so they don't make a ton of noise.

If exhaust is too loud use a tote with chicken wire and insulation as a duct muffler.
 

art.spliff

Active member
ICMag Donor
Great post I like the suspension ideas. To help with noise I'd like to mention using a variable fan controller. Plugging a fan into the wall, most fans, will be much noisier than using a dial at say 50% power. A 1000cfm fan (12" or 10" or 14") at half power will sound different (quieter) than a 500cfm fan (6" or 8" or 10") on high.
 

f-e

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Talking controllers, there are a vast array of types.
A typical dimmer switch looking one, often does little more than switch the electricity on and off rapidly. That can mean a fan going from no power, to full power, if the switching aligns with the peak of an AC wave. This is the worst type.

Better controllers, still use rapid switching, but will do so at zero cross. As the AC wave passes zero volts is the only place it can switch on. But the motor still see's full voltage, meaning full torque.

Better still are the controllers that lower the voltage. These are generally transformer based. To me they are called Variac's and will often sweep from nothing to mains voltage+10%. It's not really a good idea to run below about 30% as a fan does need to spin to keep cool. However, this continuous means of lowering the torque is effective. Sometimes a transformer with a multi-tap switch is employed rather than a variable device. It's the weight of these things that instantly tells you what's in there.

The pinnacle of control, is a variable voltage variable frequency design (vvvf drive). I have not even seen us offered one.

Moving away entirely, we can swap to a different type of fan motor. We are starting to see brushless DC fans with 3 phase controllers. These can power the fan windings though 16 different consecutive moments. Giving a pretty smooth performance. They do still whine though.



For now, the ultimate in quiet comes from a variac (auto transformer) but auto switching is a bit clunky. For close environmental control, you will likely have to stick with electronic means. Which is in the hands of the designer. Who rarely uses variable voltage.
 

Jock420

Active member
I have a problem with whooshing air coming out
Of ducting. would a Silencer at each end of rvk
Work or should I buy. A better fan
 

f-e

Well-known member
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Veteran
Let me try to locate some parts I have you may know something about them.

Interesting. I only know a little bit about plants, but a lot about equipment.


Jock your RVK is a quiet fan. I run them between silencers when I can. Often just 18" of hard pipe can make a drastic difference though, and the silencer is a much greater investment for just a little bit better. The air is all churned up and turbulent at the fan. Punching out in all directions, with pressure waves we can easily hear. A bit of pipe to keep that noise contained while the air straightens itself out works wonders.
 

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