DC piping dilemma

[TomL]

We're adding a kitchen on to the back of the house and opted to go with a full basement underneath which would become my shop. I specifically spec'ed 8' ceiling in the basement thinking i would like to run 6" dc pipe and the electric lines under a 7" elevated ply floor. Well, the breakthrough from the existing basement to the new basement was done yesterday and to my disappointment there was some sort of screwup and I have a 7 1/2' ceiling. So this leaves me with a few options and here's where I could use some guidance. a) stick with the original plan, elevate the floor 7" install 6" pipe and live with ceiling height a bit under 7'. b) go with 4" or 5" pipe under a lesser elevated floor and gain the extra 1" - 2" height c) bag the entire elevated floor plan and go with exposed dc pipe but then I'm pretty much stuck with running the electrical wire from the machines to either wall or ceiling mounted receptacles.

I have a Grizzly 1029 DC (2hp) which will be connected to a table saw, a jointer, a planer and a bandsaw. Any suggestions?

TomL

[TomL]

That was my first thought, but considering the framing is complete it might be a hell of a lot more trouble than its worth. Right now they have me by the short hairs but only until the last payment is due upon completion of the project.

TomL

[Todd]

Why not somewhere in between? How about making the floor elevated only enough to accomdate the electrical (I dunno...3"?) and run the DC piping exposed? The 7 1/2 feet you're talking about...is that to the bottom of the floor joists?

todd

[Todd]

(top-posting removed)

I'm only guessing here, but I'd speculate that the project is fairly far along and TomL is more willing to put up with a ceiling that is 6" shorter that to go through getting it fixed, even if he is in the right. This assumes that TomL has some documentation to back up his request for an 8' ceiling (i.e. approved drawings).

todd

[TomL]

He does, errrr I do. There are approved drawings.

TomL

[Bill Thomas]

Greetings,

I like b and c. Elevate the floor enough to get a level warm dry floor. Run the electrical and dust collector along the walls. Put main dust collector pipe up in the corner where the wall and ceiling meet inorder to put stuff against the wall. If you need something in the middle of the room, run it away from where you would normally walk.

S> We're adding a kitchen on to the back of the house and opted to go

[Morgans]

How about running the DC in heating "wall stack", that runs in between 2 X

4's. At 14 1/4" X 3 1/4" it ought to have ample flow, with minimal loss of efficiency.

Remember, if you are standing for long periods of time, wood is easier to stand on than concrete.

Sure makes floor sweeps easy to make!

-- Jim in NC

[Michael Daly]

Sounds good to me - with rectangular DC ducts instead of round the problem is solved.

Mike

PS - If the contractor screwed up the height, what else did they screw up that's hidden? Spec is spec - I'd scream like hell and either get the work redone or money refunded. Amount should pay for your modifications to the DC.

[Morgans]

Put the plywood down with screws; change it later with ease.

You can seal concrete any time, with the right stuff.

Use a thick white sealer (can't think of the name), if needed. A good point about having a floor, is that if it does get wet, anything sitting on the floor doesn't get ruined.

I agree about the height, but I would gladly sacrifice 4 1/4" to have the outlets and suction where it needs to be.

[Swingman]

Just went through that crap ... hell, still going through that crap, and we moved in 10 months ago. Write a letter stating the non-spec error, certify mail to the builder. Do it NOW, while it is fresh on your mind. This will be the biggest favor you ever did yourself! Safeguard the original, approved plans.

Make damn sure that the discrepancy does not depart from, or violate, the engineering plans, If so, request a "letter of exception" from the builder before your final payment.

Get it done NOW, even though you may let them off the hook later on. Builders wait till the last minute to pile on charges, you will need as much ammunition/clout on your side before that time.

Hate to be so strident, but know without a doubt that nice guys get screwed, with no kisses, in this business.

[Bob S.]

Okay....

This is based on past experience ? Changing mildew or mold covered plywood is not an easy task when you consider the safety and/or cleaning precautions not to mention the expense. I said, not putting a floor down right away - implying he's sure it's cured properly first and sealed and doesn't have a potential problem with moisture seeping through the cement. Also, most floors today are poured as floating floors. The floor has a gap space all around the outside edge by design. Any condensation / seepage / leaks on basement walls will flow into the gap first and then into the underlying drain pipe system under the floor. If it's not a floating floor desgn, then he needs to deal with getting rid of any moisture. A normally dry basement can have condensation on the block walls if they're not insulated or have provisions for air flow when the temp is cold outside and the moisture content inside goes above a certain level inside (dewpoint). Any moisture seepage up from the cement floor will eventually permeate the plywood unless its specifically sealed or treated and mold will form under the right conditions - damp, cool with little or no air flow.

You may be right but it's not quite that simple. I would advise him to do some research first because from what I read, timing can be everything when it comes to sealing cement and the products used. The so-called right stuff, is that a film sealer that needs to be reconditioned every so often or a sealer that soaks into the concrete?

The white stuff - sound like some latex wall sealer that Sears sells. Let's see...your tools didn't get wet but you've got toxic mold growing on the wet wood in the floor? Believe I'd do some more research on that bit of advice.

Each to his own and we each have our own opinions.

Bob S.

[TomL]

Yeah, rectangular pipe, never thought of that. Wonder what the dimensions of rectangular pipe would correspond to 6" round? Any idea? How is the availability of accessories such as wye connectors, bends and blast gates?

What else did they screw up? Well, the only other thing i could find, and believe me, I now follow up every day with a damn magnifying glass, was that the 4 basement windows which were supposed to be fully opening in order to accommodate fans/air cleaners were actually a type that opened only 5". This has been brought to the attention of the contractor who assured me he would remove the incorrect ones and replace with the type i specified.

TomL

[Morgans]

think of the name), if needed. A good

You have some good points, but the key question is how well the foundation waterproofing was done.

If the foundation has not been waterproofed, I would HIGHLY recommend doing it with some stuff called "Tuff and Dry" It was owned by Owens corning, but it may have been sold. It is a polymer asphalt, spayed at high pressure and high temperature. It is guaranteed to not have a damp block for ten years. Pretty impressive. Back when I was contracting, I always recommended it, and my customers have been very satisfied. I would have no worries to put down a wooden floor in my house with that stuff on the walls.

If his basement had a very -only every few years- wet problem, it still would not be an issue, from a health point of view.

You will have to make the call, on the wetness issue. I would go for it, even with some amount of risk.

-- Jim in NC

[TomL]

Jim, that's exactly what I had applied as per the recommendation of the contrator. Looked to be about 3/8" of a black tar-like substance sprayed on the exterior of the cement blocks. And yes, it came with a

10 year moisture guarantee.

TomL

[Morgans]

No worries. Your basement will be so dry, you may have to use a humidifier! No Joke!

Do the floor. YMMV

-- Jim in NC

[Todd]

I'm sure someone here can comment based on experience on the effectiveness of a rectangular duct as the "main line" in a DC system. It seems as though some considerations will have to be made.

1. The cross-sectional area of a 14"x3" duct is more than twice that of a

6" diameter pipe. Even taking into account that the actual flow will occur in a somewhat smaller cross-section due to the way that air flows in a rectangular cross-section, you could still have a problem maintaining proper velocity. Is the rectanguar duct available in other sizes?

1. I'm guessing that your standard accessories available for 6" pipe will be a) hard to find, b) more expensive, or c) all of the above for a 14x3 duct.
2. I don't know if the transitions between rectangular duct and round pipe (which you'll be making at both ends) are more prone to losses than, say, the transition between a 6" and 4" round pipe that might more typically be made.

todd

[Mark & Juanita]

How many CFM does your DC draw with static pressure drop taken into account? If you take a look at the Woodtek section of the Woodworker's Supply catalog, there is a CFM vs. static pressure drop table for their Woodtek dust collectors (I suspect that the curves are representative of most commercially available dust collectors, with slight differences for various manufacturing and design approaches). If you take into account static pressure drop, by the time you get to your machine, the flow rate will most likely be such that the velocity will fall below the recommended 3600 to 4000 fpm velocity that keeps the chips suspended in the airstream. You might be better off with 5" pipe given the size of DC you indicate.

I have posted a jpeg file to abpww that plots velocity vs. flow rate for 4", 5", and 6" pipe. Velocities significantly higher than the recommende 4000 fps cause significant static pressure drop. Take a look at They have an Excel spreadsheet that allows you to compute pressure drop as a function of your configuration. I discovered that the 4" flex pipe I have been using is horrendous in terms of SP drop -- which probably explains why my pipes have some residual chips in them. Nothing has ever plugged up, but I suspect I can improve performance significantly by going to 5" ductwork and using pipe rather than flex.