SBrooks Posted May 14, 2013 Share Posted May 14, 2013 I'm building a new chimney for a coal forge. I have tin 18 inches wide readily available. Is there a particular size recommendation for the chimney diameter? I'm liking the looks of the the Super Sucker Hood design, if that makes a difference. Thanks for your input :)! Quote Link to comment Share on other sites More sharing options...
dablacksmith Posted May 14, 2013 Share Posted May 14, 2013 I prefer 10 inch 8 inch will do in a pinch . it does depend on fuel and height of pipe (how well it draws) If you are using a coal that smokes a lot a bigger pipe will generally catch more of the smoke in my last shop i was using a 8 in pipe and had no problems but i was using coke (much cleaner burning than coal). even with a good chimney you will still need to vent the shop . good luck! Quote Link to comment Share on other sites More sharing options...
Frosty Posted May 14, 2013 Share Posted May 14, 2013 18" might be too big. It's easy to get too much stack width and the cold air column before it comes to heat will prevent it drawing. Smoke shelves help but it it's too big it isn't gong to draw well, even warmed up. 10"-12" seems to work pretty well from what I've read here. Just bear in mind I'm not a solid fuel forge guy so my opinion is largely based on hearsay. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Jim Coke Posted May 14, 2013 Share Posted May 14, 2013 Greetings Miss Brooks/ Frosty, I take it that you have tin 18in wide to make the chamber.... Best make it out of 16 gage with welded seems... 10 stack diameter is the better of the two.. At least double wall... Hope this helps JIm Quote Link to comment Share on other sites More sharing options...
SBrooks Posted May 20, 2013 Author Share Posted May 20, 2013 Thanks Everyone!!! That was my concern with the size, To get good draw. It is for coal, and I don't have the exact measurement, but will be 2 story in length. Appreciate your input very much! Thanks again! Steph Quote Link to comment Share on other sites More sharing options...
George Geist Posted May 20, 2013 Share Posted May 20, 2013 For good draw the height is much more important than the diameter. Make good and sure the top of your stack is at least 2' higher than the highest part of your roof. That formula will ensure a good draft. George Quote Link to comment Share on other sites More sharing options...
MLMartin Posted May 21, 2013 Share Posted May 21, 2013 I have worked in a number of different coal forges with different ventilation. I will not consider anything other than 12 inch round for a natural draw chimney.Having worked in 5 shops with poor chimneys I can tell you that choking on smoke will make your work day horrible. Even using a fancy professorial made side draft hood with smoke shelf and 10 inch ducting was poor and would smoke up the shop I just set up a chimney in my own shop and I am using 12 inch round with a super sucker hood. I have 18 feet of chimney. I have a fire pot that is similar in size to the many standard fire pots sold in the USA. I burn coal or coke 12 inch is the way to go. I made my super sucker out of stainless steel Good luck and do not ever settle for a smokey shop. Quote Link to comment Share on other sites More sharing options...
SBrooks Posted May 21, 2013 Author Share Posted May 21, 2013 Thank-you George and MLMartin:)!!! MLMartin Thanks for the confirmation, as that is what I was feelin. Good to know George that 2ft will give you the draw. I had been wondering if I could do less than 4ft. So looking forward to getting it up and running :) Thanks again :)!!! Quote Link to comment Share on other sites More sharing options...
jburd Posted July 30, 2013 Share Posted July 30, 2013 Getting ready to relocate my shop to our new polebarn. Need advice on chimney size. I built my own side draft hood with a 10 inch hole. I'm looking at 15 to 18 ft of chimney. I checked on the price od double walled pipe. Almost swallowed my tongue! Is there another route that I can go that is still safe? Feedback please Quote Link to comment Share on other sites More sharing options...
MLMartin Posted July 30, 2013 Share Posted July 30, 2013 You only need double walled pipe where the chimney pipe contacts the building/passes though the roof. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted July 30, 2013 Share Posted July 30, 2013 Since your set up *MUST* be just like mine---out building with steel walls, roof and trusses, I wouldn't worry about it. (Else you would have provided the necessary details right? and note if this is attached to your house FOLLOW THE CODE! to keep your insurance in force! They will be happy to collect your money and then say you didn't meet code and so they don't have to pay out---sometimes even if your forge had noting to do with an electrical fire in the opposite end of the house...) I just stuck a piece of spiral seamed duckwork through a hole. The spiral seamed duct work was 10" in diameter and 10' long and cost me US$4 at the Re-Store when they were having a sale. I bought a couple. The local scrapyard has ductwork too but they wanted US$10 a piece... Many HVAC companies also have a bonepile of old ductwork as well Quote Link to comment Share on other sites More sharing options...
Pat Roy Posted July 30, 2013 Share Posted July 30, 2013 Stephanie, Here is my experience in two shops. I used double walled pipe at the roof penetration and single wall for the rest of it. I used 8" diameter with essentially no bends. That is just barely good enough. If I had more money for the installation I would have used 10". Another consideration with natural draft is that you also need to let air into the room to replace that going up the stack, else the fire will be starved for oxygen and you may have a smoky shop. If I were still in Gray you could see my shop but I have moved to the coast. If you are on facebook and can find me there, I have an album of my shop pictures. Quote Link to comment Share on other sites More sharing options...
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