Connection for venting exhaust outside

W

wduster

New member
Hi All,

I have recently purchased a CV 1800 cyclone without filters, because I want to exhaust outside. The problem I face now is that the straight connector size does not match anything standard I can find. It is almost 9" OD in one direction and 8.5" OD in other direction (it is a slight ellipse, not circle). Inside diameters (ID) are similarly different, but slight smaller than OD. I tried 8" metal duct connectors, and it is too small for this size. It is supposed to go outside the straight connector, but I can easily put it inside with big gap on sides. 10" duct connectors are too large. Do you have any recommendations? I could purchase a short piece 8" flex hose (expensive and difficult to find), but I am afraid it won't fit over the straight connector.
 
I believe it is made for 8" PVC sewer and drain pipe either type SDR-35 (thick wall green / blue) or D2729 (thin wall white). Both have an outside diameter of 8.40 inches.
bababrown
 
I made an "duct evolution" (a square-to-round) transition that would fit over the end of the cyclone blower outlet (7" by 9" outside). First I added two hardwood blocks outside the PETG at the mouth of the blower outlet to fill in the gap to make the outside of the outlet a sold rectangle. The evolution is made of 26 gauge galvanized sheet stock (you can buy sheets at the BORG or Lowes or I'm sure at Menards if in your area). I also bought an 8" metal starter collar that is straight on one end and crimped on the other that gets added to the round end of the transition. I can email you an EXCEL file that provides the details for making the transition (I cannot upload an EXCEL file to this forum), but I have attached a copy of the originator's descriptive file at a PDF -- this copy came from Phil Thien's website DuctEvolution JoeEmenaker.pdf . Joe Emenaker developed the spreadsheet, but no longer has a website.

The drawing in the spreadsheet shows the layout for a six fold per corner transition, but the table values (and the one I made) are done with 4 folds per corner. One enters the key parameters in the 5 boxes at the top of the spreadsheet -- the duct diameter, the long and short sides of the rectangular end, the length of the transition and the number of folds at each corner. The spreadsheet calculates the balance of the parameters for the layout -- the inner radius defines the arc that forms the round end with tick marks for each fold. The long minus the short radius equal the length of the transition. When the layout is done, follow the instructions as shown, but add about an inch wide rectangle along either the right edge or left edge to provide an overlap segment to close the sheet metal at the joint (I put a small kink along this strip to allow the sheet metal to overlap and used pop rivets to close the joint. I also added a one inch strip along the rectangular edges to allow a better overlap onto the blower mouth. If you look at the diagram, the A-B segments are the short side length and the T-B, T and A-T segments are the long side of the rectangle. After laying out the tick marks, and cutting out the piece, I marked the corner folds with a straight edge and Sharpie. The folds are slight but must be straight -- unless you have a sheet metal brake, clamp the sheet metal in a wood vise and then use some straight cawls clamped on each side of the metal at the fold line and that will ensure a straight fold. After folding it to final form and pop riveting the overlap joint, I pop riveted the round end over the starter collar and closed any gaps with metallic HVAC tape. I use 8" insulated flexible duct connected to the crimped end of the start collar to move the air outside and drilled holes in the rectangular end to accept screws into the cyclone blower outlet. I sealed all seams with the metallic HVAC tape inside and out. It works very well and has minimal pressure loss (you do not want to use 6" for the outlet as you asked above due to added SP loss. I also made another transition piece to connect the outlet end to a cinder block sized vent where the air flws outdoors (my cyclone is under my shop in a crawl space about 6-8 feet from a standard vent opening in the foundation block wall).

Hope this helps. Send me a PM with your email address and I will send you the spreadsheet.
 

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I would not recommend reducing the outlet to 6". That will increase back pressure and reduce total airflow through the system. As for connecting an exhaust pipe to the outlet, you might try an 8" rubber coupling. They are made for connecting PVC to PVC or cast iron, but they are flexible enough to stretch over something slightly oversized and will compress to fit something slightly smaller. If you are using 8" rigid metal or spiral pipe, it should work. As long as your outlet fitting is oval and doesn't have any sharp corners, the rubber should seal pretty easily.
 
A friend of mine has also faced somewhat similar problem last month. He was lacking in connecting the exhaust vent until and unless he came in contact with emergency AC service Essec County NJ team on his dad's suggestion. never thought professional service would be so fast and worth hiring. You can also go with this option by contacting some licensed professionals from your area.
 
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