Ok. Im not sure what the application is. Are you hooking up exhaust to a light? Is it just a makeup air(fresh air vent)? Or is it for supply air(incomming air)? What Ive dont for my light exhause is just go get 25' of Flexible duct, insulated or not and just run it up into the attic and down into your room. Make the hole just big enough. If its a return air you want or just fresh air You can do the same or use a C-can or Ph-can (same thing) that is if you want it to look pretty. Those cans are the same ones that are in every room in your house behind the grill. If you choose that make sure and clear insulation in the attic, find a truss to attach the can to after sheet rock is gone. Not sure what your doing after your into the attic but I would suggest that all exhaust air leave the attic and all air come in from outside. Existing vents are always a nice source for that. Exhausting into the attic can be risky considering that hepa filters fail and odor can cross the attic into the house. For exhausting outside use the Fitting suggested in the ebay add.

Is it an exhaust of some sort? Whats your goal once your into the attic? I mean do you plan to pull outside air? Or exhaust it ouside or just into the attic? I think what you want to use is 25' of insulated or not insulated flexable duct (4,6,8,10,12"). Make a hole. Shove it up their as much as you can. Get in the attic grab it and pull. Leave what you wanna leave in the room1' or 24'. I have flex duct for light ventalation and square cans as room exhaust and supply and make up air (So doors dont slam shut in the house)

It is filtered room air exhaust. It goes to a register boot in another room in the house. I have just pulled the ducting through the drywall like you said but I'd like to have a duct connector on each side of the drywall. Plus, when it's just going through the drywall, bumping the ducting causes small amounts of gypsum to fall and it's not airtight. So, the fan pulls attic air into the room. Not alot, the fit is pretty tight, but I don't want any.

Is use the square cans for passive intake on the wall near the floor.

Ok. I kinda get what you want. They make something called a flu bracket. Ive only seen them up to 5". You go to a Risidential sheet metal shop and ask if the have A Flu Bracket and draft stop(piece of sheet metal with a hole in it) that is the size you want(4,5,6,7,8"). They will ask why you need one bigger than 5" if you ask. Be prepared and tell em your venting a kitchen hood and the inspector is a dick and wants a bracket. Why you dont know.lol... If they have what you want take it home put draft stop in attic over your hole. Then Screw the flu bracket to it(use small 1/4 sheet metal screws. Dont push to hard and dont wind your drill out. You drilling threw metal and into sheet rock. Sheet rock suck especially when you let the screw spin in it. Put pipe as I described before into flu bracket and tighten the bracket. Flu Brackets have a 1/4" nut and flat tip combo nut. I think flex duct with an expensive metal tape sealing the hole is easier, faster, and less of a pain in the ass but your the one there that can see what you want. This is the only way to suspend a pipe like you want. All the other ways I know are rig jobs. I looked for a pic online but couldnt find one. Sorry. I think when you see the Bracket and draft stop you will get how it works.

That sounds beyond my skills and/or toolkit. I thought I'd try attaching starter collars with flanges to pieces of 1/2 plywood with 8" holes. Then attach one assembly to the ceiling in the room and another in the attic, lining up the holes before I screw them into the drywall. Haven't had the time to try this out so I don't know how well it'll work. What do you think?

I think if you have a picture in your head of what you think will work than you've been giving it alot of thought. Just try and make it as easy on yourself as possible. If your plan was to do a piece of plywood in the attic with a starter collar on it and one in the room with one I think you have a good plan. That would get me fired at work but I think its a sound idea. You should have a buddy help you with this so that you can take turns putting screws both direction, from the top down and bottom up, all long ehough to catch the plywood on both sides. A hurricane could break that free!!!

What if you get 2 L shaped brackets that have holes on each side of the bend. use anchors to hold one side of the bracket to the ceiling and if you use a through pipe you can mark where the holes line up on the other side of the bracket, pre drill them and use nuts and bolts rather than sheet metal screws to hold the through pipe to the bracket. you coud also use 4 L shaped brackets to be extra safe but 2 will do just fine . If that doesnt make sense i can try to draw it out for you

sorry if i shoudnt have jumped in your thread by the way.

The only problem your gonna have with those L shaped brakets is that there is only gonna be a stud on one side of the pipe so three of the brakets will be useless. Anchors are risky and in my experience they only work on concrete not drywall. Especially when upside down pulling straight down. Youe could have a friend hold plywood or thin sheetmetal down up in the attic behind the sheetrock shile you screw those L brakets on. That would work,. As long as your not putting to much weight on it. Just remember to not wind your screws out in the metal. The metal your gonna get is gonna be thin and the screws wont hold shit if you wind the drill out. Dont want your pipe becoming a widdow maker to your plants.

hvac is my family's biz if you couldn't tell.

Viceline or anyone else ever use sheet metal to make reflectors?

I'm working some things out now with one. having a metal shop helps.

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