Insulated ducting for exhaust (longevity)

[Jeffoldhouse]

For those of you who have used the 8" insulated ducting for your exhaust line, have you had any abrasion problems? Is there any wear on the ducting with the fines flowing through it? I have my CV installed and the main lines are run, but still need to run the drops to the machines and the exhaust to the filters. I have turned my transition piece off of the collector up towards the ceiling with the plan to run the exhaust flex up into the attic of the shop and then back down into the filters.

Anyone had their systen apart and looked at the inside of the line?

Thanks, Jeff

[R and D Nikkel]

Ours did not stand up well and we have replaced it with 8" flex hose. It doesn't take a lot of pressure in it so when the filters get dirty (and they do if you use your system much, particularly for sanding) you can get enough pressure inside the ducting that the thin plastic tears.

[Jeffoldhouse]

That's what I figured would happen. In my work we move a lot of plastic pellets through stainless steel lines and the biggest problem we have is wear issues. The plastic actually wears holes in the line. I think I'll use 8" metal ducting and wrap it with insulation if the noise is too much of a factor. Thanks for the feed back....

Jeff

[Jeffoldhouse]

I have my transition piece coming off the cyclone turned up instead of down and then have a metal 90 to turn my line back across the attic. I had about 3 ft of straight 8" straight duct running from there into another 90 down into the filters. The noise was too loud to suit me, so I went ahead with the 25 ft of insulated flex duct. I added it to the end of the 3 ft of straight metal duct and just made a long loop across my attic and then back to the 90 into the filters.

What a difference!! The noise level dropped dramatically and I am hoping that the metal 90 coming off the transition piece will take the brunt of the turbulance and wear so that the flex holds up longer. I figure that if I get a year or so out of the flex that it is worth the price for the reduction of noise in my shop. It was a very easy (10 minutes) fix and hopefully will last.

Jeff

[Danscyclone]

Jeff, I had the same problem after moving my cyclone to a shed and running the exhaust thru about 20 ft. of 8“ hvac. I replaced about 10 ft of the hvac with a 25 ft insulated flex and that totally eliminated the noise. I lost 35 cfm with the change but plan to gain some back by cutting down the flex a couple ft at a time until I can hear the noise and then replace it with the heavier flex. I’m using a 2hp motor with an airfoil impeller and the CV gets 20+% more airflow.

[TexaCali]

I realize this thread is a little old, but can someone tell me where to get 8" insulated duct hose? McMaster only sells in 25' rolls and I just need a few feet. I'm venting outside, so there shouldn't be much back pressure on the hose.

Thanks!

[Jeffoldhouse]

I found mine at Home Depot. Lowes carries it too. Comes in a box about 3 ft long and its all compacted in the box. After a year of using it I'm still glad I bought it. It works great and I just checked it last week for interior wear...doing just fine.

Jeff

[TexaCali]

Thanks Jeff! Picked some up at HD.

[tdenap]

I'm in the process of building a transition box and cleanout for a "low ceiling" installation. I will connect the new transition to the CV supplied 90 via flex exhaust, I think. How are you all connecting this 8" flex exhaust to the CV transition?

thanks!

[McRabbet]

I built my own transition from a small piece of galvanized 24 or 26 ga. sheet metal from Lowe's using this link to calculate the correct shape for cutting out the sheet metal pieces and then pop riviting it together. Just take the appropriate measurements of the outlet rectangle from the mouth of the blower and make the transition (known as a "square-to-round"). After latingit out, I used a Sharpie to define the crease lines and made the bends by pressing the metal over the corner of my assembly table. Be sure to add enough for attaching both the round and rectangular ends. I do have sheet metal experience, so that helps. If you cannot make it yourself, take the dimensions to your local HVAC shop and they can make one for you for a fair price.