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Thread: DC ducting

  1. #1
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    DC ducting

    Click pics for full size pics.


    OK, finally need some ducting advice. now I got some vaca time & the wife is away I want to get it finished. The first pic here is where I want to put my DC system. As you can see I got elect there already.






    Next two pics is of the outside of the shed to the basement window I have to use.







    As you can see the run will not be very long. I also know that you should use as little of the 90 elbows for good flow of air.


    1. I was wondering if I should use instead of the 90 should I use two 45 elbows.

    2. Should I use the thin walled PVC? I saw it has some type of black plastic inside of it will that do anything to the flow of air?

    3. I'm not going to glue any joints just a pressure fit. Since we get some real heavy snow up here will the thin wall PVC have any type of cracking issue due to extreme cold?

    4. I have the HF one., am I going to have to put it on a type of wood pedestal so the intake more lines up with the window? if so then I'm afraid of the height issue maybe to tall & the bag be constricted by the ceiling???

    any advice is very welcome.

    Chuck

  2. #2
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    lets see if i got this right so far chuck dense today your DC is gonna go in the shed and the lines are going threw the basement window?
    if this is the case, then first of all a DC can only pull so much..depending on its size.. and the length of run affects that aswell..so you might be asking for to much for the DC to be in the shed and pulling from the basement..so we need to know the size of the DC and then what your plans are for distance and what you are attempting to do in the basement..
    If in Doubt, Build it Stout!
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  3. #3
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    Chuck, if I understand you correctly, the shed is the structure on the left in this photo, and the basement window is on the right. I'm also assuming your Harbor Freight DC is going into the shed, with a pipe running from the shed, through the basement window, and into your shop. Is that all correct?



    If that's the case, I do think two 45 bends will be better than a single 90 elbow. I also think I'd look into running the intake pipe through the shed wall instead of the shed window. I think it'd be easier to get sealed up. I could be wrong on that, though.

    On the PVC pipe questions, I'll let someone who knows more about the stuff chime in.
    Attached Thumbnails Attached Thumbnails Chuck's Shed and Basement.jpg  
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  4. #4
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    1 If you only go with friction fit you are going to have too much loss from leakage at the seams.
    2 Are you running two lines? one for the dust and one for the return air? for it to work the air needs to be returned to the room.
    3 The 2 45's would be better than the 1 90 for air flow.
    4 Be careful of static electricity build up in the pvc they dont recommend it for just that reason. You are a lot safer using metal pipe and grounding it.

  5. #5
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    Quote Originally Posted by Rich Soby View Post
    ...4 Be careful of static electricity build up in the pvc they dont recommend it for just that reason...
    There's a lot of debate on that one, Rich. I know a number of experts are of the opinion that there is no risk, since they feel the right combination of dust density, oxygen, and airflow don't exist for dust explosion in a home shop DC system. It's my understanding that there has never been a documented case of PVC piping causing a dust explosion in a home DC system. On the other hand, there are a number of intelligent people who would prefer to avoid the chance entirely (however slight it may or may not be) by simply not using PVC piping in the first place.
    When the going gets weird, the weird turn pro. - Hunter S. Thompson
    When the weird get going, they start their own forum. - Vaughn McMillan

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  6. #6
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    use long sweep fittings and if you could use a y instead of the 45's you would have better flow.. i used pvc and havnt had any trouble and i used the schedule 40 rather than the S&D but if you seal the connection on the S&D you should solve rich point that he made..use the metal furnace tape to seal it..
    if you were closer i got a batch of metal ducting and fittings that you could have
    If in Doubt, Build it Stout!
    One hand washes the other!
    Don't put off today till tomorrow!

  7. #7
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    Larry,
    I have this one HF 2hp DC Also I never heard of "long sweep fittings"?
    The length of run is from the basement window Vaughn showed then it's only approx 8' to the lathe.


    Vaughn,
    You are correct the shed is to the left with the large windows & the basement is the one you said. Wife will kill me if I drill a 4" hole through the shed, sorry not a option.


    Rich,
    I thought being in the shed it would take air from the shed???


    Question:
    Do you think the metal would be cheaper or easier to use then the PVC?

  8. #8
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    Quote Originally Posted by Vaughn McMillan View Post
    There's a lot of debate on that one, Rich. I know a number of experts are of the opinion that there is no risk, since they feel the right combination of dust density, oxygen, and airflow don't exist for dust explosion in a home shop DC system. It's my understanding that there has never been a documented case of PVC piping causing a dust explosion in a home DC system. On the other hand, there are a number of intelligent people who would prefer to avoid the chance entirely (however slight it may or may not be) by simply not using PVC piping in the first place.
    I agree with everything you said Vaughn, I have read both the reports that say its fine and the chicken little reports and several in betweens. I just felt it needed to be mentioned as there is always a chance. Even if it doesn't cause an explosion, just the stored up static on a dry cold February morning deciding it likes your flannel shirt better when you walk by and nailing you, or worse deciding to make the jump when you are operating a machine is more than enough to "not go there" for me....


    A report I recently read said that "thorough testing" has shown that the danger doesnt manifest itself until cfm exceeds 1500 and then it's "rare"

    Also, metal pipe, even though still a lot more expensive than pvc, has come down to the point where it is at least reasonably priced, and for most home runs you arent looking at a huge investment. Also, you can focus the pipe on the straight runs and use the flex hose which is very reasonable on the drops to the machines. and all can be grounded very easily.

    But since whenever there is a 99 out of 100 chance something wont happen. I usally fall into the minority......
    Last edited by Rich Soby; 09-18-2011 at 01:01 PM.

  9. #9
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    Quote Originally Posted by Chuck Beland View Post
    Larry,
    I have this one HF 2hp DC Also I never heard of "long sweep fittings"?
    The length of run is from the basement window Vaughn showed then it's only approx 8' to the lathe.


    Vaughn,
    You are correct the shed is to the left with the large windows & the basement is the one you said. Wife will kill me if I drill a 4" hole through the shed, sorry not a option.


    Rich,
    I thought being in the shed it would take air from the shed???




    Question:
    Do you think the metal would be cheaper or easier to use then the PVC?
    It would release the air from your shop into the shed. The air needs to be returned to the room it was removed from to work properly, also if that is where your furnace is (if you have gas or oil) the dc can potentially create the path of least resistance for the exhaust gasses and draw them into the shop instead of letting them release through the chimney

  10. #10
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    rich, why does the air that has been sucked in the DC need to be brought back into the shop except for the possible heat and cooling issues you mentioned? in my case and i have seen others this way as well its ducted outside..
    If in Doubt, Build it Stout!
    One hand washes the other!
    Don't put off today till tomorrow!

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