DIY Flowhood 4 Dummies

Discussion in 'MYCO-TEKS' started by Ratdog, Jan 23, 2015.

  1. Ratdog

    Ratdog New Member

    Jan 21, 2015
    --------------- DIY FLOWHOOD FOR DUMMIES ---------------​

    Hey guys... first post over here at the Tek! Thought I'd bring this one over and share it
    with you kind folks over here. This is a write up of how I built my first flowhood. Hopefully
    I'm not too long winded & someday someone will find it helpful! :D


    2 Sheets of 3/4" sanded ply wood - ($70)
    2 Pieces of 2"x1" furring strip - ($2)
    Box of star drive wood screws - ($7)
    Tube of silicone all purpose sealant - ($6)
    Variable speed controller - ($20)
    Small spool of 12-18ga wire - ($5)
    Roll of duct tape - ($3)
    Few wire nuts - ($3)
    3 Prong plug - ($3)
    14"x14" Ultra Allergen Pre filter - ($14)
    99.99% 24"x24"x6" HEPA filter - ($160 shipped)
    Squirrel Cage Blower - (free)

    TOTAL $300 - $330

    --------------- HELPFUL TIPS ---------------​

    Get a friend to help out! Having an extra pair of hands throughout this whole process
    is going to make it a lot easier!

    Pre cut the wood at Home Depot or Lowe's when you go to get! They will be able to
    cut it perfect in just a few minutes.

    Pre-drill all of the holes for the box. This will keep the plywood from splitting when you
    run the screws into it. How we did it was with 2 drills... the electric with the drill bit & then
    came in behind that with a cordless drill to shoot the screws. This made things go super
    fast so if you've got tools around go for it! Another thing that will help is using the star bit
    screws (most of the screwboxes will come with the bit). They grab much better and won't strip
    out on you while trying to put them in.


    The biggest thing that will make this project easier is skipping the exact matching of a
    blower to your filter. Using a speed controller or choking down the fan works!

    --------------- THE FILTER & THE BLOWER ---------------​

    The filter I used was a 24"x24"x6" wood framed 99.99% HEPA from
    I had to call the company to place the order, which took about 25 days to reach my
    doorstep, including the time it took to manufacture (they are made to order). The main
    reason I picked the 24"x24" filter is because I wanted to be able to G2G into spawn bags.


    I learned from reading EvilMushroom666's build that he was able to wing it on
    his blowers by calling and asking local HVAC companies if they had any old squirrel cage
    furnace blowers sitting around that they might be willing to part with. As it turns out,
    most of the time they will have a few, and be willing to let you have one for relatively next
    to nothing. I ended up knowing somebody who knew somebody who worked in HVAC, and
    all I had to say was that I wanted a blower to move air out of my musty screened in porch
    during the summer.

    I chose to shoot for a bigger blower than a smaller one because it is always possible to choke
    a bigger blower down, whereas a smaller one would need to have a bigger motor
    installed, defeating the purpose of getting it for free. In the end, the blower I got
    moved so much air that I wasn't able to choke it down enough by blocking the intake, so I
    went to Harbor Freight & bought a speed controller that the motor plugs into.

    If you're using a used blower for your project it will be a good idea to take it apart and
    clean it before installing it to keep a bunch of nasty shit from immediately getting stuck to
    the back of the new HEPA filter. This is very easy & should be pretty self explanatory.
    I cleaned with soapy water then rinsed all the parts off in a 5 gallon bucket.


    --------------- BOX CONSTRUCTION---------------​

    I decided to go with a 2" cube for my box. I'm sure you could go with a smaller plenum if
    your blower is smaller. My advice is to build the box around the filter, that way you can be
    sure that it fits properly. Doing it this way will also help you to put the 4 sides together,
    (the top goes on last after the blower is mounted) and keep all of the angles right.


    Once I had the 4 sides are together, I measured the depth of the filter inside the box. Then
    I drew a line using a straight edge all the way around the box at this measurement. This is
    for the furring strip, which is used to butt the filter up against & hold it into place.


    For the top part of the box I traced the shape of the outlet on my blower & cut it out with a
    jig saw. I used some small nuts & bolts to attach it to the box but screws will work too.
    Make sure to silicone the shit out around the edges where the fan meets the wood.


    Once the top was screwed on I took the caulk gun & ran a bead of silicone around every
    joint inside the box, including around the furring strip on the inside. After that I put on a
    latex glove and smoothed it all out with my finger, ensuring that the silicone gets
    pushed up into the cracks & makes a proper seal.


    Now the box should fit around the filter like a glove. I had to use a rubber mallet and a bit
    of strip to convince it to slide back into place. After I got it pushed back in I screwed in
    the furring strip around the outside face.


    I also chose to build a top box on my flowhood. There was extra plywood so I figured why
    the hell not. Doing this made it quieter and also gave me a really good way to mount the
    pre filter and a paper towel holder. After you build the first box you should be able to put
    the smaller one together without much explanation...just make sure to drill a small hole
    on one side for your wires to come out of. Once you get the top box on, silicone all
    around where the two boxes meet and construction is done.

    --------------- WIRING THE BLOWER ---------------​

    Most of the time these blowers have a few different speed settings available just by changing
    which wire you give power to. Mine had 4 different speeds on it, each corresponding to a
    different colored wire going to the motor. The white wire coming off of the motor will be
    the constant. Connect that to the silver screw in the 3 prong plug. Test out each of the colored
    wires and figure out which one you think is going to work best for you. Whichever colored wire
    you use, (I used yellow) connect to the gold screw. It took about 30 minutes of messing with
    the wiring on this thing to get it right. It should be simple enough & there are plenty of videos on
    youtube if you find you need some help!


    Once the plug is all wired up, plug it into the bottom of the speed controller & start playing
    around with it. You want the flow coming out of the filter to be just strong enough to bend
    a bic lighter 60-90° without blowing it out.


    Attached Files:

    Last edited: Jan 23, 2015
  2. muskie

    muskie Myco-Backpacker Mushroom Doctor Expert Identifier

    Sep 22, 2014
    Lazy River Road
    Looks great, man! Love all the great pics :bravo:
    Ratdog likes this.
  3. FallenOak

    FallenOak Mushroom Cultivator Mushroom Doctor

    Jun 21, 2014
    Great write up! You are certainly a craftsman, I love the paper towel roll lol. The tip for cheap blower fans is golden also ;)
    Last edited: Jan 23, 2015
    Ratdog likes this.
  4. Ratdog

    Ratdog New Member

    Jan 21, 2015
    Thanks guys!! The paper towel roll is a must!! :hatsoff:
  5. ToRn2biTs

    ToRn2biTs mycelium muncher

    Dec 15, 2014
    Deeep South
    Bad ass man, very nice good & write up.
    Ratdog likes this.
  6. Papa_Legba

    Papa_Legba Member

    Aug 26, 2014
  7. tripdawg420

    tripdawg420 Active Member

    Jun 7, 2011
    damn real nice
  8. mannaman

    mannaman Active Member

    Mar 15, 2014
    three miles from the harbor.
    Sweet, nice write up!
  9. treewood

    treewood mediocre mycologist Moderator Mushroom Doctor Supporter

    Aug 1, 2011
    all you forgot was the JOB!