isaacsbees

Ok y'all, I think I'm going with 12" pipe through the window, just so I don't have to punch through the wall. I'm gonna take Frosty's idea to get something like a blazo can and fit it up with the forge, making sure the area is less than the area of the 12" pipe. I just went down to our local HVAC supplier got some 12" stuff. Thanks again to everyone for your help on this! -Isaac

I'm not opposed to cutting a hole through the wall... I've just never cut through a concrete wall What would be the best way to do that? Ok, 3 feet minimum over the roof and concrete backer board, got it. For the Blazo can, is it something like this?

Thanks David! I never thought to use cement board... good idea! I'm leaning toward just ordering the 12"... how tall do y'all reckon it'd need to be to give a good draft? Could I connect 4" with my 8" to make some of the 12" I'll need? Thanks for the quick responses guys!

Hi everyone, this is my first post on the forums... I apologize in advance if this post isn't where it belongs or in the correct format. I've been lurking around on here for the past few days without an account just taking in all of the information about various systems of sucking smoke away from coal forges. After forging outdoors for awhile without a hood (still very new to forging), I've decided to move indoors. I noticed y'all like details, so I tried to get as many as possible: -Forge has a 12" x 10" firepot set into an old 18.5" x 16.5" forge body (measuring from the top of the sloped edges) -Cinderblock behind the forge is 15.5" x 7" and the top of the block is roughly flush with the upper back lip of the forge -The forge/cinderblock is 10" lower than the windowsill -The window is approximately 27" square and I have cut out a piece of 3/4" plywood to fit into it (still not quite sure how I'm going to safely pass the pipe through the plywood without it being a fire hazard) -The building has a gently slanted roof, and this window is on the side with the high end of the slant -From the top of the window to the highest point of the roof is 30" (bottom of the window to the roof is 57", forge to the roof is 67") -I have access to some 8" round, galvanized vent pipe left over from another project: one 2ft piece, one 5ft piece, two adjustable 0-90 degree elbows, and a rain cap (I know I will need more than this, but it's what I have on hand at the moment) -For cutting/drilling/connecting metal, I have a stick welder, tin snips, hacksaw, jigsaw, miter saw, angle grinder, power drill, and various blades/bits. I don't have a plasma cutter. Can I get away with using 8-inch round ductwork for a smaller forge like this with the proper hood (I know that 10-12 inches is preferred)? If so, how much more pipe do I need to buy to make the stack tall enough? Or am I better off buying larger round or square duct? What is the best shape for the ductwork to preserve flow in this case? Should I do an "S" shape (up, out of the window horizontally, then up again) or will that slow the flow too much? Is a Super Sucker the best route to go down? I've also seen people use 55 gallon drums and was thinking about that as well. In general, I'm sort of lost on this project and the fluid physics/geometry involved and need some guidance from more experienced hands. Thanks for reading! -Isaac