how close to ceiling to run overhead ducting?

[James Baker SD]

I've finally got my cyclone moved to its new home in an adjacent room to my shop (garage) and a hole through the wall to bring the ducting back into the shop. The question I have is about running horizontal runs parallel to the ceiling to form the main branches of my system.

1. how close to the ceiling should I get? Does it really matter if it is 1" away versus 6" away? How about touching?
2. what is the best way to support the horizontal runs? just metal straps screwed to the ceiling or is there something better?

Thanks.
James

[johnny means]

I like the "as high as possible" approach. Can't hurt when moving longer/higher stuff around.

[John M. Smith]

I put my 8" pipe 1" from the ceiling. That put the 6 "pipe 2" from ceiling. I built saddle blocks that were flat on top and curved to fit the pipe. attached these to the ceiling, and then used plumbers strapping to tie the pipe to them. very solid installation. If all your pipe is the same diameter, I see no problem strapping it right to the ceiling.

[David Kumm]

The benefit of hanging it a couple of inches from the ceiling is it is easier to wrap the joints with tape. you can caulk or use sealant but if you take things apart the tape works better and is easier. Spiral pipe and heavy gauge fittings make a solid installation and strapping works just fine. Dave

[Alan Schaffter]

In my mind the only consideration is whether the ducting will obstruct any of the lighting. Support it the cheapest way you can devise.

[Peter Kelly]

One thing I found that worked really well for hanging duct was the steel strap hanger that Grainger sells: http://www.grainger.com/Grainger/DUC...FZ3?Pid=search (http://www.grainger.com/Grainger/DUCTMATE-Strap-Hanger-6PFZ3?Pid=search)

Mount it to the ceiling with a screw and feed an appropriate sized hose clamp through it. Dust pipe will be within 3/8" of the ceiling surface.

[Ole Anderson]

The higher the better for clearance under the duct when moving boards or ply around. Leave just enough clearance to tape the joints. I just used these steel hangers for duct runs perpendicular or at an angle to the joist.

http://www.pennstateind.com/store/N-HB06.html (price is for five hangers)

My basement ceiling had exposed joists, so it made the installation easier, and on runs parallel to the joists, I tucked them between the joists so the top of the duct was near the top of the joist and just used an extendable straight duct support there. But then I had 7'-6" ceiling height.

http://img.photobucket.com/albums/v152/CJ7ole/My%20Shop%20Jan%202011/IMG_7493.jpg

[glenn bradley]

I'm in the higher the better camp but, I live in a single story and live alone so sound transfer is a non-issue.

[ray hampton]

you can buy a roll of strap with holes at regular intervals along its length which will allow you to made a hanger the size that you need

[Jim Andrew]

Saw a pic one time on this forum where a guy screwed a strip of wood to his ceiling joist, under the ceiling, and cut a hole in a piece of plywood that fit the pipe, and screwed that to the strip of wood. Looked like a good support for the duct. You could use whatever thickness lumber you are comfortable with, 1 1/2 x 1 1/2 would be easy to screw to. And the plywood doesn't have to be a lot bigger than your pipe, maybe 1 1/2 or 2" wide around pipe.

[Gordon Eyre]

Here is a pic. Of how I ran mine on a 10 ft ceiling.

http://www.pbase.com/greyflash/image/109252901.jpg

[Paul Cahill]

Well I took a completely different approach and went low. The underside of my duct is only 6" 10". This my second iteration. The 1.0 version was right up against the joists, but I was very disappointed with the air flow of 400 CFM or less.


242864

After taking some measurements on flow and pressure drop, I set about eliminating all the restrictions that I could readily address:
- 6" drops with 7" header;
- direct discharge outside through 8" line;
- streamlining the routing;
- raise the cyclone as much as the motor would allow and take the header straight in (and consequently lowering the clearance).


242865 242863

I was concerned I might have overdone it, but even thought it looks a little odd, it has not been a problem at all. The header is above the door openings. As far as what I set out to do, namely get the air flow up, I am very pleased and am at 1,000+ CFM. Initially I thought I had screwed up and got too small a cyclone. There is no doubt that a bigger impeller would have allowed more flexibility with respect to pressure drop, but it turned out fine.

Paul