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  1. #1
    Returning Member Jim Murphy's Avatar
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    Ductwork in crawlspace.

    Well, it seemed like a no-brainer to build a crawlspace so I could run ductwork under there. At this juncture, I need opinions from y'all. Here's what Ed at ClearVue Cyclones said:

    As a suggestion, there are several reasons for not putting the pipe in or under the floor. Putting the ducting in the floor has several inherent problems. Most importantly, I don't see a lot to be gained. You would end up with blast gates coming up from the floor where they are hard to reach. As you have to turn them on and off a lot, blast gate placement is an important consideration. They are best installed at 4 - 5' off the ground where they can be easily operated. The next problem is versatility. I don't care what layout you start out with, it most likely won't be the one you end up with. You will add machines, decide you want to move machines and change your layout and an in-ground or under floor duct system will be difficult or impossible to move. I already built my "dream" shop and I glued all of my "4" PVC pipe together because I thought it would never have to be changed. Within 6 months I was cutting it and throwing fittings away because I had glued it together. Now, I have a 6" PVC system and nothing is glued
    together. Hope I've given you some ideas.

    Okay, I'm not going with 4", it will be 6", and I will not glue PVC. I'm chatting with the nice folks at K&B in G'boro about a metal pipe system, and I got this back today:

    - Are you sure you want to run it under the building. It always sounds like
    a good idea but I don't know anyone that was glad they did it 3 years later.


    I put a good deal of thought into where everything would go before I applied for the permit. I placed it where I wanted it, and after six months, I would change nothing. I'm planning for a future lathe, and I know exactly where it will go.

    My crawlspace is 36" to the bottom of the joists, level all the way through. I built it that way. It's reasonably dry, because I put in french drain with socks around the perimeter.

    This shop is my toy. I will NEVER make anything for sale or contemplate any sort of production work. The dust collector is for convenience and health. Believe it or not, I do not aspire to have a 66" bandsaw or 42" thickness sander, or any other behemoth gear. My only "need" is a kick-butt planer to replace the 22-580 at some time in the future, but I'm already running a 6" line to the lunchbox that should easily handle a bigger planer.

    An overhead system would conflict with my installed lights. It would be a challenge to get the saw exhausted without having a downtube conflict with cutting area. I would have to step around the downtube for the bandsaw all the time based on where the factory ports are located.

    I tend to think it would take more piping total, since every port is about a foot off the floor and would need an uptube to the sky, whereas with an underfloor each machine would dump down and there would be only one uptube for everybody.

    FWIW, Mr. Pentz endorsed the idea of going low.

    So, skilled, erudite and wholly sagacious fellow sawdust makers, who can talk me into or out of going under the floor?

    ...I have finally reached the age where my wants and needs have regressed to my early childhood:
    ---I want everything and need nothing.

  2. #2
    Returning Member Travis Porter's Avatar
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    Re: Ductwork in crawlspace.

    Before I built my shop and while I was finishing it, I laid everything out in Visio 10 different times, decided how I wanted the layout, and after 2 years, I switched it around. You will ultimately change where something is placed IMO. If you are like me, you will miss something or add a new tool or gizmo, and your layout is going to change, that is a given.

    If I could do below the floor dust collection, I would have, but it just didn't seem realistic, and I couldn't swing the price of a wood floor at the time. To me, if you can fill the holes if you decide to move something, then I would. I believe Alan in little Washington has his below and McRabbet as well, and I have not heard any negatives from either. IIRC, they have both rigged gizmos/levers to work the blast gates and not have to go around and bend over to get to them. Having the open space above without the piping would be a preference to me. IMO, go for it. It isn't like you are going to have more joints because of it, and if you work your gates out so you can get to them like you want, you have nothing to lose.

  3. #3
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    Gofor's Avatar
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    Re: Ductwork in crawlspace.

    36" crawlspace? I say go for it. After spending a week replacing a leaking sewer in a 14" crawlspace last month, I would say you have the space you need to rework the system in the future if it absolutely needs it.

    Go
    Practicing at practical woodworking

  4. #4
    McRabbet
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    Re: Ductwork in crawlspace.

    Jim,

    I'm also in favor of unglued 6" PVC and for running it under the floor. I am a little more fortunate than you because I have a sloped crawlspace under my basement shop that ranges from 42" minimum to over 110" at the outer walls. I currently have a 1 HP Penn State Industries unit mounted on a small raised platform that I turn on and off with a Shop Fox Remote Control. This little DC unit serves one machine at a time through 4" PVC runs for now, but I plan to upgrade to a larger unit very soon. I also "pre-treat" machine output through a garbage can chip collector made from plans in Shop Notes Issue 55 (I can send you the plans as a PDF file if you need it).

    I also made a two-headed blast gate to isolate the two primary legs of my duct runs. One blast gate opens and the other closes remotely with a rope and pulley system fed up to my shop.
    My system works okay for now, but I get sick and tired of changing flexible hose from the chip collector to different machines. I have never had any clogs or fitting failures (to avoid them coming apart, I'd put a pair of short sheet metal screws through your joints that don't protrude into the airstream). I only need to empty the bag on my collector once every 4-5 times I empty the chip collector because it is pretty efficient. I am planning a full upgrade to a 6" duct system and a 2-3HP dust collector in 2007. There is info in the Download Library on making your own blast gates -- it's easy.

    In your case, I would include clean-outs accessible through a trap door or drop-in floor panel. And check out Alan in Little Washington's system, which is run under his second floor shop. I hope he'll chime in with suggestions. By the way, the blast gate issue mentioned by the Clearvue is solved by correct placement of the gates.

    BTW - Click on the thumbnail pics for bigger pictures.

    HTH. Rob

  5. #5
    toolferone
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    Re: Ductwork in crawlspace.

    Take a look at this page! Nimrod's shop floor
    I also ran ductwork under my slab, no regrets.

  6. #6
    Returning Member Jim Murphy's Avatar
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    Re: Ductwork in crawlspace.

    Have you found a source for thin-wall PVC for your 6" upgrade? The lack of any S&D 2729 anywhere in NC has been the impetus for me pricing the metal tube. 6" Schedule 40 is HEAVY whether you're working on a ladder or on your back.
    ...I have finally reached the age where my wants and needs have regressed to my early childhood:
    ---I want everything and need nothing.

  7. #7
    toolferone
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    Re: Ductwork in crawlspace.

    I bought all my fittings at McMaster-Carr on line and I bought the pipe at Ferguson's here in town. I have also heard that some of the box stores have 6", it is not next to the sch 40.

  8. #8
    McRabbet
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    Re: Ductwork in crawlspace.

    Our local Lowe's carries the green bell-end sewer pipe in 6" diameter, but not the 6" white S&D that you'll want. As Tom said in his post, try Ferguson's or Hajoca or any other larger plumbing supplier. Lowe's does carry several 6" fittings (Couplings, 22-1/2 els, 45 els, 6x6x6 wyes, 6x6x4 wyes), but they do not carry sweep 90's. You'll need to get those from McMaster-Carr.

    Rob

  9. #9
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    Re: Ductwork in crawlspace. *w/pics*

    Well, since my has name been mentioned, I guess I'd better weigh in.

    First as has been said, I have under floor DC ducting. It runs just below the ceiling of the garage and punches through to my shop where I need it. I have easy access to all the piping- though I need a ladder :lol:. Two drops punch through in the middle of the shop floor for the jointer and the tablesaw (they have trap door covers if I need to roll a machine over that area- which I do occasionally). The remainder of the branches actually come up behind and punch through a knee wall along one side of the shop. One drop comes up along the opposite wall inside my benchwork for the mitersaw. I can reconfigure my systim if I need to relocate a drop. A new hole would need to be made in the garage wallboard ceiling and in the Advantech flake shop floor- I will be doing that because I want to add a drop over by my lathe. Relocating an existing drop would require I patch the old hole in the floor.

    Tablesaw floor "drop" and blastgate



    Jointer floor drop being used to pull air though and clean one of my cartridge filters with "reverse air flow"



    I used 6" S&D pvc for my runs (I have a few 4" drops). It is all dry fit. I added a tiny bead of silicone as a final seal after everything was together. Silicone, NOT Latex, caulk works well on the outside of fittings because it doesn't stick real well and can be rubbed off with a finger if you want to reconfigure, and remember the piping is under suction so the stuff will stay in place.

    Ed Morgano has a point about the location of the blast gates. I will be adding remote manual actuators for my blast gates so I don't have to bend down or reach behind machines to open and close them since they are at or just above floor level- the actuators will be homemade versions of choke/throttle cables (piano wire in nylon tubing). I'm trying to decide what to do with the actuating end. I was thinking of a lever/flag type of setup so I can easily tell which blast gates are open and which are closed. I usually run with the tablesaw blast gate always open because it is not easily accessible. My 3hp system has enough suction to serve more than one machine at a time, however. 2 1/2 years later, and I'm still glad I did underfloor ducting. :-D:-D:-D

    By the way, while S&D may be harder to find than Sched 40 and is close in price FOR THE PIPE, check out the differences in fittings!!!!! My Lowes carries fittings for the S&D (actually ASTM 3035 fittings which are the same ID size) and they are about half what a Sched 40 fitting costs. e.g. 6" S&D wye cost about $12 - $14, while a 6" Sched 40 wye can cost up to $26 or more!!!!

    I have manual LVC start/stop buttons conveniently located around the shop- I figured I'd lose the remote transmitter, just like I'm always misplacing my pencils and calipers, etc. :-D:-D:-D

    Bottom line- if you've got a comfortably accessible crawl space- go for it. Much neater appearance too!!

  10. #10
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    Tarhead's Avatar
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    Re: Ductwork in crawlspace.

    Jim,
    I have my cyclone in the shop in a back corner and use 6" white PVC as the main line branching off to a 5" flex for the Tablesaw and separate 4" flex runs for the bandsaw and jointer/planer/drillpress(Quick connects). There is a brick kneewall about 2ft high along the wall where the cyclone is mounted with a 2/4 ledge. I ran the main line down the the kneewall ledge and strapped it to the wall and ledge and inserted 6" PVC wyes strategically along the line. I like the fact that the main line only protrudes ~2.5" into the shop and is located against the wall where I can push the back of the bandsaws, jointer and planer against it. This minimizes the length of the flex runs. I can take pics of this when I get home this weekend if you want to see what it looks like.

    Major suckage as far as the Clearview . Marty Baucom and I visited Ed in Punkintown this past summer and were totally impressed. It really, really sucks:lol: and helps keep things clean in the shop. I would have gone that route had a very good deal not come my way.
    Mark

  11. #11
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    Re: Ductwork in crawlspace.

    For those installing, getting ready to install, or adding to their DC ducting I was in Lowes tonight and saw a yellow tag on one of the PVC S&D bins- I could not believe it, they had 6" X 6" X 6" S&D wye fittings marked down from $18 and change, to $.91, yes, that is 91 cents!!!!!! Not sure if you'll find it that way at any other Lowes, or not.


    Here is the receipt to prove it (I bought the last two they had): :-D:-D:-D


  12. #12
    jeff...
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    Re: Ductwork in crawlspace.

    whoa .91 cents did you feel like you committed a crime?

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