Morten311 Posted August 6, 2016 Share Posted August 6, 2016 Hi everybody I have made a side draft hood ( super sucker design ) but it is not working properly. i have installed my hood on the side of my forge and put the ventilation tube through a window since the landlord won't let me drag a chimney through the roof. on the other side of the window i have a 90 degree angle to point upwards with a little "hat" to stop rain from entering and i use a Ø200mm ventilation tube. if it is too windy out side i cannot stand i my workshop since air from outside is blowing in through my chimney and into my forge. i could really use some help with this problem since i am almost getting grey hair from this problem. i have tried with two ventilator blowers, a small one that broke do to heat and a big one that also broke due to high temperature. both blowers were sitting next to the window and still broke. now i have tried with this form of ventilation but it still doesn't work quite right. please help me if you have any idea of what i am doing wrong. thanks in advance. Link to comment Share on other sites More sharing options...
Frosty Posted August 6, 2016 Share Posted August 6, 2016 How high above the peak of the roof is it? It needs to be a minimum of 4' higher than anything within 10' (I think). Move your forge closer to the window, the shorter the horizontal run the better. Use a T on the outside 90* one arm points downwards the other upwards to the rain cap and the horizontal run from your hood enters the leg. Envision a capital T on it's side coming out of a forge hood. How this works is first it prevents cold air from filling and blocking the stack so your hood will draw as soon as warm air enters it. It's other function is to give down drafts an easy route out, they'll go straight down rather than make the turn and travel horizontally against rising hot air. Lastly it eliminates the need for a rain cap, any that falls in will just keep going very VERY little will make the turn and flow horizontally. Frosty The Lucky. Link to comment Share on other sites More sharing options...
gote Posted August 6, 2016 Share Posted August 6, 2016 There is a place to discuss this- not in "building designing a shop" but in "Chimneys hoods and stacks". I suggest you take a look at the thread Flashing around the chimney This is cheap, simple and works. I see Frosty has forgotten to tell you to show your location. Please do. and Welcome. Link to comment Share on other sites More sharing options...
Morten311 Posted August 6, 2016 Author Share Posted August 6, 2016 okay so i just did what frosty told me to do, but it is still not working quite right. i dont have a lot of ventilation tubing left so i only have about 150 - 200 mm of tube going upwards. i dont know if it is enough of a height, but if cold air blows in even if it is just a little breeze outside, in my head it should be okay. i also dont want to spend a whole lot of money on ventilation tubes if it does not work. ventilation tubes and equipment is quite expensive here in little denmark. but i am going to order a 400mm ventialtion tube to go outside and drag it up and just a little bit over the roof, unless you guys say something else. Link to comment Share on other sites More sharing options...
Latticino Posted August 6, 2016 Share Posted August 6, 2016 Drat, I had a good, what I thought would be helpful post, but it disappeared (moderators?). Don't have time now to recreate it with all the theoretical stuff, sorry. Bottom line is, my suggestion is: Cap the lower TEE and install P-trap for drainage (prime that trap with water so it doesn't leak air) Add stack height, that is what drives the flue exhaust (take Frosty's suggestion and move forge closer to wall and use interior duct in vertical) prime stack by burning paper in hood before use to start flue going get rid of the restriction before the TEE 8" diameter is rather small, flow resistance may impact the effectiveness. Link to comment Share on other sites More sharing options...
Morten311 Posted August 6, 2016 Author Share Posted August 6, 2016 well i have a problem about moving the forge closer. first i have sealed the window off ( except a hole for the ventilation ) with plexiglass to stop air from blowing in to my workshop since i dont want to get sick and dont like to wear too much clothes since i like to move freely. second the is a small concrete wall next to my forge and the landlord wont let me break it down. i am currently looking for a new place to be, but for the moment this has to do. but thanks for the idea. Link to comment Share on other sites More sharing options...
Frosty Posted August 6, 2016 Share Posted August 6, 2016 If you only have 200mm. of vertical pipe above the horizontal it isn't going to draw. PERIOD. You need a MINIMUM of 155 cm. ABOVE the top of the roof to prevent back drafts. A back draft is a condition caused by wind turbulence caused as it blows over a structure and turbulence finds smoke stacks and chimneys to blow down. If you can't more the forge closer to the window you can't. That isn't your problem though, your stack is just NOT TALL ENOUGH. At a guess, if you were in a single story building you'd need to add at least 3m. to your stack to give it a chance of drawing. Frosty The Lucky. Link to comment Share on other sites More sharing options...
Morten311 Posted August 6, 2016 Author Share Posted August 6, 2016 okay thanks for the help frosty i will order home a 4m ventilation tube, because then it will reach just over the tip of the roof, maybe a little more. but thanks anyway. it is nice to be able to get some help when you are completely new to blacksmithing. Link to comment Share on other sites More sharing options...
Frosty Posted August 7, 2016 Share Posted August 7, 2016 That'll help a lot but take it at least 1m. above the peak or turbulence will make back drafts anyway. Glad to help a new fellow become completely and hopelessly addicted to the craft, we LOVE company and pictures you know. Frosty The Lucky. Link to comment Share on other sites More sharing options...
Morten311 Posted August 7, 2016 Author Share Posted August 7, 2016 i will remember that Link to comment Share on other sites More sharing options...
Steve Sells Posted August 7, 2016 Share Posted August 7, 2016 5 hours ago, Morten311 said: well i have a problem about moving the forge closer. first i have sealed the window off ( except a hole for the ventilation ) with plexiglass to stop air from blowing in to my workshop since i dont want to get sick and dont like to wear too much clothes since i like to move freely. second the is a small concrete wall next to my forge and the landlord wont let me break it down. i am currently looking for a new place to be, but for the moment this has to do. but thanks for the idea. no one said break it down, move it closer towards the window meter or 2 Link to comment Share on other sites More sharing options...
Michael Cochran Posted August 7, 2016 Share Posted August 7, 2016 Is that the wall with the rag on it in the second picture? If so, I'd suggest moving the forge right behind it shortening your horizontal run. Just remember the wall when you step up to the forge so you don't kick it. Link to comment Share on other sites More sharing options...
Latticino Posted August 7, 2016 Share Posted August 7, 2016 Forgot to add one of the key caveats from my missing post: makeup air. The fumes you want to vent need to be replaced by something, be sure to have a window or door open somewhere else in the room. Link to comment Share on other sites More sharing options...
SReynolds Posted December 30, 2016 Share Posted December 30, 2016 This obviously works very very well. 8" pipe. 3' horizontally and 3' vertical. It doesn't extend verticlally far above and beyond anything as suggested. Link to comment Share on other sites More sharing options...
Marc1 Posted December 30, 2016 Share Posted December 30, 2016 Considering 8" is on the small side, I would also ... besides going up past the roof top ... get rid of the 90 degree bend and make a straight diagonal section from the forge to the opening in the window and then a 45 bend vertical up. It may not be 45, but you will have to adjust it to the real angle. Link to comment Share on other sites More sharing options...
Morten311 Posted December 30, 2016 Author Share Posted December 30, 2016 i got my side draft working now. maybe not the best but it removes at least 70 % of the smoke which is a huge improvement. all i had to do was to extend my chimney up and above the rooftop. nothing else has been changed. but thanks for all your helpfull tips and tricks. Link to comment Share on other sites More sharing options...
Steve Sells Posted December 31, 2016 Share Posted December 31, 2016 really? and all this time we assumed you followed the general guidelines and had it above the roof line to begin with ... no wonder. Glad its working for ya Link to comment Share on other sites More sharing options...
Glenn Posted December 31, 2016 Share Posted December 31, 2016 Now you are sucking smoke and air from all sides. You can add wings to the side and top of the hood to channel the smoke into the chimney which will help. Try the top and away side first. Does not have to go all the way down to the the forge. Be sure and preheat the chimney before you start a fire. Couple sheets of newspaper will do. Get the fire ready and then preheat again with a couple of sheets of newspaper. Build the fire slow and hot to get the smoke moving up and out. Link to comment Share on other sites More sharing options...
ThomasPowers Posted January 3, 2017 Share Posted January 3, 2017 I was welding over the holidays and listening to my 10"x10' chimney "sing" while the fire was *hot* was a joy Link to comment Share on other sites More sharing options...
Latticino Posted January 3, 2017 Share Posted January 3, 2017 Singing= high speed exhaust flow=effective fume capture and disposal=good design Note: colder outdoor temperatures will improve the chimney effect for correctly designed vents as well. Link to comment Share on other sites More sharing options...
ThomasPowers Posted January 3, 2017 Share Posted January 3, 2017 Mine is just a 10' long piece of spiral ducting 10" in diameter stuck out a hole in my wall at a steep angle. Hole was originally for the woodstove chimney when the wall was a roof for a friend's house. A bad hail storm caused an insurance replacement and I was gifted the "hammered look" remains to use for my shop wall. It's even blue, of course my shop is 4 different shades of blue (propanel and roll up door) Link to comment Share on other sites More sharing options...
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