IronFist Posted December 20, 2008 Share Posted December 20, 2008 I know this has probably been asked/ answered before but I cannot find anything on it here. I lit my first fire in my coal forge this morning and it burned great with heat escape thru the flue but it got extensively smokey in the shop. Bad enough to have to walk outside. The dimensions of my forge are: depth-27" front to back width-24" hieght-32" depth from center of firepot to rr wall- 12" flue diameter- 6" The 6" flue pipe rises up 8" and then immediately turns 90 degrees to exit through the wall penetration, 90 degrees up to the stack cap. I can see that the start smoke and heat are escaping fine but once the fire really starts to catch or I have to add green coal, it smokes the xxxx out of me. Is it going to take time to "burn-in" or am I doing something wrong? Like the aforementioned, it did die down once the coal got going hot and I forged 4 table legs fairly quickly. But when I loosened the heart of the fire and placed fresh coal around, it smoked again. But, does that fire burn hot!! A lot hotter and forge temp was reached a lot faster than my blast forge. Thanks for any help. Quote Link to comment Share on other sites More sharing options...
dablacksmith Posted December 20, 2008 Share Posted December 20, 2008 your flue is too small..... and with a 90 in it is too restrictive...and what coal are you useing? if you cant increase flue diameter you might go to coke ... less smokey .good luck! Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted December 20, 2008 Share Posted December 20, 2008 WARNING when it "clears" you are still poisoning yourself. you can not see CO and CO2, but if its burning it is still being produced. Quote Link to comment Share on other sites More sharing options...
IronFist Posted December 20, 2008 Author Share Posted December 20, 2008 I could possibly enlarge flue diameter pending cost. I'm using the blacksmithing coal from Centaur Forge. Would anyone recommend a straight through the roof flue versus one with bends? Quote Link to comment Share on other sites More sharing options...
Rich Hale Posted December 20, 2008 Share Posted December 20, 2008 As you add green coal you must keep it wet, a soup can nailed to the end of a stick works great,, just sprinkle a little on the green coal and it will help not only with the smoke but also with helping it "coke" up to be added to the working fire. Also for a flue to draft it must have a source of air. You need a large opening for fresh air to enter the shop. If the shop adjoins the residence get two CO detectors. Put one in the shop and one in the home near the shop. Do not forge in a shop that is not really well ventilated. Quote Link to comment Share on other sites More sharing options...
Glenn Posted December 20, 2008 Share Posted December 20, 2008 Go to a larger chimney, 10 inch is recommended. Side draft chimneys work better than hoods. The closer the chimney is to the edge of the fire pot the more smoke, etc is removed. Using coke, charcoal, or other fuels burn cleaner but will still produce CO2 and CO. The only way to move these invisible gasses out of your work area is with a larger chimney. GET a CO monitor and a smoke detector and use them both. Quote Link to comment Share on other sites More sharing options...
Frosty Posted December 20, 2008 Share Posted December 20, 2008 Another possibility is your shop is too tight. You MUST have makeup air to replace that going up the flue. It'll draw at first but when the pressure differential inside is greater than the strength of convection going up the flue it stops drawing. Frosty Quote Link to comment Share on other sites More sharing options...
Ian Posted December 20, 2008 Share Posted December 20, 2008 An alternative is to find an electric blower (a junk automotive unit for example) and plumb it into your chimney so that the air flow enters from the side at around a 45 degree angle pointing UP. Mount it at above head hieght to keep it out of the way and to avoid heat issues and it'll act as an extractor (by venturi) sucking up air without the need for draw. Essentially a variation on forced extraction, but by doing it this way you dont have to worry about an inline blower on a Forge flue. Quote Link to comment Share on other sites More sharing options...
Frosty Posted December 20, 2008 Share Posted December 20, 2008 An alternative is to find an electric blower (a junk automotive unit for example) and plumb it into your chimney so that the air flow enters from the side at around a 45 degree angle pointing UP. Mount it at above head hieght to keep it out of the way and to avoid heat issues and it'll act as an extractor (by venturi) sucking up air without the need for draw. Essentially a variation on forced extraction, but by doing it this way you dont have to worry about an inline blower on a Forge flue. That'd be induction ala Bernoulli's principle. A Venturi is something else entirely, similar but different. Still a viable solution by any name. Frosty Quote Link to comment Share on other sites More sharing options...
devon blacksmith Posted December 21, 2008 Share Posted December 21, 2008 How tall is your flue? is it beond the ridge of you building is it afected by cooling how far is the hood from the fire how steep is the slope of the hood all of these and a lot more can stop the flue working properly, Quote Link to comment Share on other sites More sharing options...
IronFist Posted December 26, 2008 Author Share Posted December 26, 2008 Thanks for all of the recommendations from everyone. I nipped it in the bum by routing the flue straight through the roof. Havnt had the same problem again. I do still have a bit of smoke when adding green coal, but its my first coal fueled forge and I've to teach myself how to properly use it. Thanks again! Quote Link to comment Share on other sites More sharing options...
Ian Posted December 27, 2008 Share Posted December 27, 2008 I stand corrected on the venturi effect, I said it based on the literature that came on an old vacuum pump I had that worked by blowing very high pressure air through one pipe and across the top of another, it sucked the air out of the pipe making a vacuum. They said it was a venturi, so we were both wrong Live and learn Quote Link to comment Share on other sites More sharing options...
Ron Hicks Posted December 27, 2008 Share Posted December 27, 2008 I did the same thing - got to have a bigger pipe. I used the 6 in stove pipe but I used 2 to make 1 large pipe. I took them apart at the seams and attached them together at the seems. They will lock together I made a collar that fit the pipe and welded it to the top of my sidedraft hood . It works really good Need a straight run of pipe above the ridge of roof Quote Link to comment Share on other sites More sharing options...
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