Chimneys, Hoods, and Stacks

In reading a magazine called Fuel Oil News, April 2006, I stumbled onto a article called Flue Pipe Design by George Lanthier, who thanks Tim Begoske and John Cotton of Field Controls for the chart. The following information relates to the fuel oil industry but may provide guide lines for forge chimneys. Mr. Lanthier refers to a rule of thumb about “the chimney connector shall not be longer than 75% of the portion of the chimney above the chimney connector inlet.” If you have (as in his example) a 35 foot tall chimney and you deduct 5 feet for the height of where the flue pipe goes into the chimney, leaving an actual chimney height of 30 feet. Seventy five percent of t…

A funnel is a device that takes a large opening and reduces it down, usually so you can pour liquids into a small mouth or opening in a container. You choose the funnel to match the task at hand, that is to say a small funnel in the kitchen for moving spices from a large (quart) container into the little bitty containers that fit in the cabinets. The large end of the funnel if maybe 2 inches in diameter and the small ind about the size of a wooden pencil or less. If you pour too fast you over fill the funnel and get a mess all over the counter. If you are putting oil in the motor of the car, you have a funnel with a 4 to 5 inch opening on the large end a…

I was driven to action the last months, due to the rainy spring that we have had here in the Netherlands. Good for the farmers, but it kept me from enjoying the open air setup that I was using. So it became time to install the flue that I have been planning for a year now, into the shed. I figured that it might be helpful to share an experience, perhaps it might help someone out. Having originally planned to go through an available masonry channel, I had purchased some 250mm single-walled stainless flue pipe. That didn't work out: the channel wall was too irregular to fit. Reading on this forum told me that 250mm or 10" is considered to be the minimum feasible d…

Built the hood, used 2 6” diameter piping to create the 12” flue. It’s going to go straight out of the roof in my barn. My question is where did you guys get a 12” double walled pipe/flashing/storm collar/cap that fit the flue?

So I am working on building an outdoor charcoal/ future coal forge table. Just to help pull some smoke up and away from me and use a canopy above the work area uto stay out of the sun I have an 8” black stove pipe T that I was considering using for a quasi side draft. Leaving the bottom of the T slightly open and reducing the opening towards the fire pot to a 6”. Would this work to pull some of the smoke and hopefully prevent to many fire fleas from getting up towards the canopy?

We just had a masonry fireplace built as part of a screened in porch. We used it this season for the first time and have been getting smoke back into the porch and build up on the face of the fireplace. The box is 39(w)x29(h)x25(d). We had three fireplace companies come out to clean and they all said that the flue is too small. Looks like it is about 12.5x8 but with the tiles the flue opening is 11x6.5. Is the flue too small? Would a stainless steel liner help instead of tiles? Should we have the contractor rebuild from the box up? Any other suggestions? Thanks!!!!

I saw on YouTube that it's best hood possible for side drqft forge, so I asked neighbour for old boyler and Ian planing to cut it to make super sucker Anny suggestions or tips are more then welcome As example Ian using this video

Hi everyone - my name is Bill, and as you all may have guessed, I'm new here. I'm setting up my forge, and have run into a crossroads of sorts on how to proceed. I'm trying to decide which size and set up I should go with to vent my hood. I'm on the fence on whether I should go straight up through the attic space, and out the tin roof, or make a 90 degree out the wall, and then up to appropriate height. I'm also not certain on pipe diameter... Six inch, 8 inch? I've been pouring through information both here, and around the internet, and I'm seeing conflicting opinions. Attached are some pictures of my set up. I welcome any and all information. Thanks for reading…

This is my first post here and I figured I could start my adventure into learning to forge by getting some advice on proper forge ventilation. I purchased a great coal forge for myself from Centaur Forge. It came with a half hood and also blower and I have been practicing outdoors while I sort out the location I want to install it in one of my workshops. This morning I had some contractors out that deal with wood stove installations and to make a long story short they are quoting me between 4-5k to install 14' of pipe through the roof of my unfinished workshop. The hood that came with my forge was designed for an 8" pipe and the contractors said that this woul…

Hello, I noticed today my side draft hood and chimney have rotted out. It’s too bad, because they’re both only about 1 1/2 years old! My original plan was to replace with stainless, but I have some concerns. I’ve read in other forums that even stainless (316T being the preferred grade) don’t hold up particularly well to the acid from burning coal? 12” flue pipe is crazy expensive. I’d rather not spend the money if it won’t last. The other option I’m considering is building a new hood with much thicker plate. (the current one is 16 gauge) but even the 1/4” flat bar around the opening looks closer to 3/16 now…so I’m not sure how long that would last eith…

I recently opened a new shop. I am renting a 35x35 shop with a 20-foot ceiling. One wall has a 20-foot-wide bay door. I placed my forge next to this massive door, with a few fans blowing across to keep the smoke flowing outside. It works some of the time, unfortunately, it is often too windy here, and most of the smoke blows back into the shop on windy days. I cannot safely operate the forge like this and need to find a way to keep the smoke flowing outside. My current thought is to get a forge hood to block the wind coming in from outside and to funnel the smoke better, and a duct blower to help ensure all the smoke is propelled outside. This would ensure the smoke …

The hood on my forge is due for replacement. It's rusting so badly, that it's dropping huge rust flakes on the hearth causing some massive klinker. It was ok until the rain cap blew off. It was a few months till I got the chance to get it fixed. Had to replace the lower 5 foot section of flue pipe as well. That was a couple of months ago. Now the whole thing needs to be replaced. I'll be going with a side draft this time. Instead of the barrel that I have now.

My existiing coal forge set up includes a hood that is 45x34 at the bottom, 56" high and 34x45 at the top. The 10" steel chimney extends 48" above the hood where it enters the ceiling/flat roof. The chimney extends approximately 12 feet above the flat roof. The distance from the fire to the bottom of the roof is approximately 9 feet. I want to add an exhaust fan. The chimney draws reasonably well but would like to minimize smoke/soot that doesn't get drawn out with this passive hood and chimney. Received a proposal for a fan rated to 650 degrees, but price is $7,000 without delivery and installation. Proposal suggested at least 12 inch chimney and bigger hood.…

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 th…

Hi all. Now moving into a new shop and unlike the old one, this one has an opening I can "in theory" run a passive flue through (In the past I had to work with a fabricobbled centrifugal extractor fan, which worked VERY poorly). For reference, this is for a small, bottom blast coal forge (forge pot about 10" diameter at top). Theres a window behind where the forge is going with an opening leaf with an apeture of about 10.5". Going through the roof is NOT an option (rented shop, strict requirements). I'd like to install an overtop hood (I cannot afford the extra 12" space behind the fire for a side draft flue) which will start as a 12" hood (8"-1…

Hello everybody, I couldn't find any info online about making a proper gas forge exhaust gas extraction system, so I decided to build one and make a little video about it. There are very nice smoke extract fans for sale online (ruck.eu), but I decided to buy a cheaper regular steel box fan and retrofit it with a little trick a learned from "Smederij de Waard - Wanroij" in order to keep the motor and bearings cool. The system had to be as quite as possible, the gas forge itself is very quiet, so I don't want the sound level to be overruled by the fan. Two big sound dampers are used, also to suppress the noise as much as possible for the surrounding neighbors. …

I've looked for concrete answers on this question, but mostly ran into questions on coal forges or speculative solutions, so I'm curious if someone has any input or has tried this. I have a fairly large 2 car garage (2 cars + room on either side for a shop, could probably fit 3 in) with several windows and a large door. I'd like to run my propane 2 burner NC forge in the garage and vent the heat/fumes outside. I understand the CO issues and have CO monitors at floor level, head level, and a gauge next to the forge, along with fans in each window and a fan blowing air into the garage from the outside via the garage door. My main concern is preventing heat and fumes f…

Had a galvanized chimney for the last 12 years. It rot away. Had this one installed last Saturday: all stainless steel. It will outlive me.

I have made my chimney as close to the Hofi style as I could. 14" x14" side draft of 3/16 steel plate. 12" diameter air handling tube 10' high. I would like to put a cap of some sort on the chimney top, about 12" above the top of the chimney, will this cap restrict the flow of the chimney?

I'm about to build a new metal chimney in my workshop for a side draft forge. I was wondering what's the ideal thickness for a metal chimney's plate wall. I've only found a tube with 0,6mm wallthickness. Is that enouguh? What do you think?

I just got myself a super sucker forge hood and I’m loving it. I couldn’t find a 12” pipe but a friend of mine gave me some 13” that’s working really well. I’m concerned that the pipe might be galvanized. I’m not sure how to tell if it is for sure. If it is in fact galvanized will that be a problem? I know galvanized releases toxic fumes if it gets hot enough but will the chimney reach that high of a temperature? I don’t want to be breathing in toxic fumes. I’d like to know what folks think about this. Thanks in advance

For a while I’ve had a smoke problem in my shop. My shop is too smokey almost all the time. I have a large Centaur Forge hood and an 8” stove pipe. My chimney doesn’t go straight up through the roof as I’ve seen a lot of blacksmith shops do. It goes through the side of my shop then straight up. I really am not sure what to change to make my chimney draw better. It’s like it just can’t draw all the smoke, only some of it. That makes me wonder if I just need a larger stove pipe but I wanted to ask opinions before I just start trying everything. Hope someone has some suggestions. It is much appreciated! Thank you!! Merry Christmas

Hi all, I have a piece of insulated ten inch i.d. pipe that I'm going to use for the inside shop, and I need a suitable hood to use it with. I was thinking about the super sucker side draft design, as a full chimney hood above my forge is not suitable for me at the moment. Can I use a downscaled design, as the super sucker plans call for 12 inch i.d. pipe, or is there another design that is more suitable to use with 10 inch i.d. pipe? Thanks for your replies. ~Jobtiel

The final significant project in my shop is the chimney for the coal forge. I am planning to do a Super Sucker style hood. I have some (about 10’) of stainless double wall pipe that has an 8” ID, which I understand is a bit undersized as most recommend 10-12” to ensure good airflow. My question is, if I use that 8” ID pipe until I transition through the roof and then go to 10” single wall, how will that impact my airflow? Will there be a benefit to using the 10” for the final run, or would it make little difference if the initial section is only 8” ID? I’d appreciate any input. Thank you!

Hey all. I have a problem with my current stack which is 200mm (7") and 5.5 meters tall and it has worked before but after moving to a new workshop it does not. I gave gotten sick and tired of my workshop being full of smoke, so i have been thinking about going industrial size. I have 5 sheets of stainless 1mm thick and making the new stack either 640 or 560mm in diameter or 22 to 24" and 4.5 meters in total height. Is it too big or not? Its hard to find a proper answer.