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Thread: Air Cleaners - Questions re placement. (including using 2 units)

  1. #1

    Air Cleaners - Questions re placement. (including using 2 units)

    I have a couple of JDS-750’s. Just 12 x 24”, 1/4 HP.

    I know most instructions say to mount a single unit high, but why is that? It seems to me that most fine dust is near the floor. (literally, in “the dust zone.”) So why NOT put it there, except for space reasons?
    I've never seen an explanation for the "high" suggestion.

    Also, the most common suggestion is something like "It should be hung 1/3 of the way from a corner of the longest wall and near the wall for best air flow." I assume that means sideways, yes? But doesn't that just swirl air around the room's perimeter? What about all the dust in the middle?

    ------

    And how about when using TWO cleaners?

    I figure two small ones must surely be better than one larger one, but what might be the optimal placement for them?


    I’m thinking it might be possible to position the so they create a continuous “circular” movement through the shop. Any ideas on how to do this? I was thinking maybe one a few feet below the ceiling, facing UPWARDS, so it exhausts downward. Then the second one near the floor, also facing upwards, maybe with a curved “air guide” underneath, to direct its output across the bottom of the shop.


    Or maybe both mounted “sideways” on two adjacent walls, so as to blow air around the perimeter of the shop? (I tend to work closer to the walls than to the center of my work space.)


    Is there an even better (conventional) way to use two units?
    Last edited by Allan Speers; 04-21-2019 at 2:40 AM.

  2. #2
    [QUOTE=Allan Speers;2919947]I know most instructions say to mount a single unit high, but why is that?

    ​Fine dust behaves like a gas and rises towards the ceiling.

    Also, the most common suggestion is something like "It should be hung 1/3 of the way from a corner of the longest wall and near the wall for best air flow." I assume that means sideways, yes? But doesn't that just swirl air around the room's perimeter? What about all the dust in the middle?

    Dust in the middle will make its way outward with the circular motion.


    ------

    And how about when using TWO cleaners?

    I figure two small ones must surely be better than one larger one, but what might be the optimal placement for them?


    I’m thinking it might be possible to position the so they create a continuous “circular” movement through the shop. Any ideas on how to do this?
    long way

    One on a long wall a third of the way down and the second on the opposite wall a third of the way down from the opposite corner. See highly technical illustration below.

    ------------filter----------------------------------


    ------------------------------------filter----------


  3. #3
    ^ Thanks.


    But in that highly technical drawing, which way is the air moving?

  4. #4
    Left to right
    and right to left.

  5. #5
    Join Date
    Jan 2010
    Location
    Tampa Bay, FL
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    1,868
    I mounted my two opposite each other, pointed in opposite directions at about 7 feet high. I have the small Jet and the large Jet. And, despite the large room and very tall ceilings, it is impressive how well 2 units work. I can get the air far, far cleaner than ambient air, and even terrible dust is cleaned up quite rapidly.

    It's amazing how high the particle counts get on my Dylos meter when I'm grinding the concrete raised access floors (and the workers don't wear any protection). About 30 times higher than what I see from woodworking. The air cleaners suck that stuff out of the air at an impressive rate.

    So even with non perfect locations, two work extremely well for me.
    If you drive at the speed of light, do your headlights work? - Steven Wright

    If a man points at the moon, an idiot will look at the finger.

  6. #6
    Quote Originally Posted by Peter Christensen View Post
    Left to right
    and right to left.

    Thanks.


    Will do.

  7. #7
    Well now, tonight I found a pdf of the manual for another 1/4 HP JDS air cleaner. I has recommendations for placement. This is very different from the above recommendations. Now, actual user feedback is often better than the suggestions from some factory tech, but this does make me scratch my head:

    It say all units should be "as high as possible."
    It says that a single unit shold be in the CENTER of the shop.

    And it recommends the following for using 2 units: (I hope the attachment works)

    JDS Position Recommendation .jpg

  8. #8
    Circulation is key. It is a waste of time to put a filter in the middle of a room and ask it to catch something without circulation. As well heat naturally rises with airborne dust. I work closely with fire rescue prevention and detection devices... they all work off of suspended detection at ceiling height. Are you suggesting the fines would be closer to the floor or airborne?

    Sure… Two would be better than one and four would be better than two... and circulation with better filters would pull out more. I have a wind tunnel at work that has cleaner air then anything I’ve ever taken in.... but a good HEPA filter face mask solves a lot of issues.

    Forget about the wind tunnel. We have fire rescue at my college. Nothing replaces PPE!
    Last edited by Matt Mattingley; 04-23-2019 at 2:20 AM.

  9. #9
    Matt, the question is no longer height, but placement.


    I'm sure Peter's way works well, but it's completely different from what JDS recommends, so I have no idea which method to use.
    It's not exactly easy to "just move them around," with the room full of test smoke, or whatever.

    You make a good point about heat moving the fines. Maybe the advantage of an "against the wall" setup like Peter suggests, is that you could have your heaters directly below the air cleaners' intakes, to take advantage of that phenomenon. (in the winter, at least.) - assuming that, like me, you use two smaller heaters instead of one large one

    Still looking for more opinions.....

  10. #10
    Put it the way JDS recommends.

  11. #11
    I have two air filters, one I built 25 years ago and one I inherited from the old man's shop. I also have a Reznor ceiling mounted unit heater I have mine mounted so that all of them cause the air to rotate in a circular motion. I also have the output of the one I made go through a piece of insulated ducting (mostly for noise) and pointing down, so that the warm air from the ceiling gets pushed down into the cold air below.

    The second air filter might be overkill for my 24 x 28 shop, but it does help clean the air quite nicely and quickly. I mounted it originally because I didn't have any better idea of what to do with it. Now that it is there, I don't have any plans to take it down.

  12. #12
    Join Date
    Apr 2017
    Location
    Michigan
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    641
    Fine dust does not rise naturally, it settles but very slowly. Random currents and diffusion will cause it to mix rather generally. Treading around on the floor will stir up dust. This is a significant source especially on a concrete floor. Chances are there is more dust in the air lower down so I think air cleaners should pick up there. They should distribute cleaned air above breathing level. Forcing circulation is complicated, it can work for or against your efforts to clean the air.

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