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I worked as an electrician in a steel mill where they did hot dip galvanizing by running the steel sheet through a huge molten vat of zinc. Everyone there had mild cases of upper respiratory congestion. It was only after I left there that it went away and later read of some medical research describing the exact same thing I went through. That was almost 40 years ago. Most dangerous place I ever worked. California, just 40 miles east from San Francisco, go figure.

The compressor tank that you are using for the firebox appears to still have paint and/or primer on the exterior surfaces. That could be another source of the smoke you are experiencing. It appears that you have access to an oxyacetylene set up, use it with a rosebud to burn off that paint/primer and also burn off the zinc of any piping. Black pipe would have been a better choice, but after you burn off the zinc, that's what you'll have left.
 
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Discussion Starter #22
Just a couple of thoughts come to mind. Bear in mind that I might not have understood the entire set up you have. Just delete thesw if you have already addressed the issues.

The flue exit in side the burn chamber should be at, or very close to the highest point in the burn chamber, othewise you are allowing heat/gases to accumulate in the top of the burn chamber before they can exit via the flue. Could be the flow is stalled and or circling around the top of the burn chamber before going against the natural flow, having to push downward to find the flue exit.

The burn chamber has to have at least a little more draw capacity up the flue than the feed air coming in. Not sure how your fans are arranged, but if there is any situation where there is more incoming air flow than exiting gases, the flow is
going to back up in the burn chamber and it is going to puff smoke.

Very interesting project. I bet with a little adjusment here and there, it is going to work just great. Let us know if you find out how to correct it.
I am thinking we need to cut out 6 inch pipe from burn chamber to the reclaimed barrel and also go to an 8 inch chimney pipe. And I think you are correct. The pipe flu going into the burn chamber is too deep. We were trying to create a reburn gasification on this stove. Not quite there yet
 

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Discussion Starter #23
I worked as an electrician in a steel mill where they did hot dip galvanizing by running the steel sheet through a huge molten vat of zinc. Everyone there had mild cases of upper respiratory congestion. It was only after I left there that it went away and later read of some medical research describing the exact same thing I went through. That was almost 40 years ago. Most dangerous place I ever worked. California, just 40 miles east from San Francisco, go figure.

The compressor tank that you are using for the firebox appears to still have paint and/or primer on the exterior surfaces. That could be another source of the smoke you are experiencing. It appears that you have access to an oxyacetylene set up, use it with a rosebud to burn off that paint/primer and also burn off the zinc of any piping. Black pipe would have been a better choice, but after you burn off the zinc, that's what you'll have left.
Most of the paint has burned off already. Guess I need to update my pictures. The smoke is coming out the door when it is opened to add more wood and the smoke is back flowing out the fans that are feeding the fire.
 

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Discussion Starter #24
I am thinking we need to cut out 6 inch pipe from burn chamber to the reclaimed barrel and also go to an 8 inch chimney pipe. And I think you are correct. The pipe flu going into the burn chamber is too deep. We were trying to create a reburn gasification on this stove. Not quite there yet
I need to change all 6 inch pipe to 8 inch and only let the pipe go into the burn chamber about 3 inches instead of 8
 

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The 6" pipe is probably adequate......get the zinc out of the fire....although one person told you it is not dangerous, a few of us with first hand experience know otherwise...it can be extremely toxic and have long term effects ...there is no reason to have it into the chamber at all...I was thinking that the tank itself was galvanized..wood will also burn better if on a grate, raise off the bottom of the chamber ..as far as gasification you might get some information from this guys videos
 

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Most of the paint has burned off already. Guess I need to update my pictures. The smoke is coming out the door when it is opened to add more wood and the smoke is back flowing out the fans that are feeding the fire.
Opening the door will allow some smoke out, but not as much as what you are describing. That shows that you have draft problems. Even attempting to force the gases inside with the fan(s) is not going to help much until you correct the draft flow. The exhaust out of the firebox should be flush with the top otherwise the gases and smoke will swirl around trying to find another way out.
 

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The 6" pipe is probably adequate......get the zinc out of the fire....although one person told you it is not dangerous, a few of us with first hand experience know otherwise...it can be extremely toxic and have long term effects ...there is no reason to have it into the chamber at all...I was thinking that the tank itself was galvanized..wood will also burn better if on a grate, raise off the bottom of the chamber ..as far as gasification you might get some information from this guys videos
Sure would be nice if these people wore a mic so they could be heard.
 

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I have a 60+ gallon old air compressor tank I was going to make into a wood stove,but I was just going to use a "barrel stove kit" or copy & build the parts like those myself..

With round barrel shaped stoves,I find any obstruction in side them tends to kill the draft and that includes baffles or heat exchange pipes or chambers..you really need a good draft,often it is the chimney or its location at fault,not so much the stove..I have issues with back drafting in my garage wood stoves due to there being trees & branches a few feet away from and above the chimney--even with a cap on it,there can still be back puffing out of the air inlets when a gust of wind blows,I guess the trees direct the wind right down the flue..
Also the flue pipe needs to go straight up if at all possible--anything more than one elbow fitting will reduce draft and aggravate the back drafting condition..

I had planned to cut holes near the top of the tank on both sides and weld in pieces of 2" pipe ,so the pipes will sit very close to the top of the barrel (the top being the place the flue pipe would go),close enough so the draft of incoming air from the door area wont be affected...the flames will lick the pipes and heat will come out of them by natural convection...a friend took a 275 gallon oil tank and cut it in half,and welded a bottom onto it,and used a hole saw to make a lot of holes thru both sides to weld pipes into ,the same basic design,and that thing is incredible,it'll heat a 50 x100 foot metal building in an hour or so,its main drawback is it'll eat a whole tree in one day...

It is very similar to the stove and shop in this video..

As for galvanized "zinc chills",I've gotten them more than once from brazing galvanized sheet metal from old furnace ducts to patch up rotted floors in vehicles--you'll be sick a day or so,but as long as you don't confine yourself in a enclosed area full of the "zinc smoke",by using a fan.you most likely wont suffer any serious hazard..
I used some galvanized stove pipe in my garage,I found the zinc only burnt off on the first 2 feet from the stove's exhaust outlet,and the rest stays below the temperature limit needed to make it emit fumes or create a hazard..
I only used it because I had it and it was better than freezing to death,and hoped maybe it may last longer than plain stove pipe..
 

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I have a 60+ gallon old air compressor tank I was going to make into a wood stove,but I was just going to use a "barrel stove kit" or copy & build the parts like those myself..

With round barrel shaped stoves,I find any obstruction in side them tends to kill the draft and that includes baffles or heat exchange pipes or chambers..you really need a good draft,often it is the chimney or its location at fault,not so much the stove..I have issues with back drafting in my garage wood stoves due to there being trees & branches a few feet away from and above the chimney--even with a cap on it,there can still be back puffing out of the air inlets when a gust of wind blows,I guess the trees direct the wind right down the flue..
Also the flue pipe needs to go straight up if at all possible--anything more than one elbow fitting will reduce draft and aggravate the back drafting condition..

I had planned to cut holes near the top of the tank on both sides and weld in pieces of 2" pipe ,so the pipes will sit very close to the top of the barrel (the top being the place the flue pipe would go),close enough so the draft of incoming air from the door area wont be affected...the flames will lick the pipes and heat will come out of them by natural convection...a friend took a 275 gallon oil tank and cut it in half,and welded a bottom onto it,and used a hole saw to make a lot of holes thru both sides to weld pipes into ,the same basic design,and that thing is incredible,it'll heat a 50 x100 foot metal building in an hour or so,its main drawback is it'll eat a whole tree in one day...

It is very similar to the stove and shop in this video..

As for galvanized "zinc chills",I've gotten them more than once from brazing galvanized sheet metal from old furnace ducts to patch up rotted floors in vehicles--you'll be sick a day or so,but as long as you don't confine yourself in a enclosed area full of the "zinc smoke",by using a fan.you most likely wont suffer any serious hazard..
I used some galvanized stove pipe in my garage,I found the zinc only burnt off on the first 2 feet from the stove's exhaust outlet,and the rest stays below the temperature limit needed to make it emit fumes or create a hazard..
I only used it because I had it and it was better than freezing to death,and hoped maybe it may last longer than plain stove pipe..
Guys up here built a lot of those. Yea Zinc poisoning sucks been there a couple times feels like a bad bad flu.
Lots of good ideas for stove on youtube.
 

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We used respirators while welding the galvanized pipe in a wide open area.i am trying to understand your reply. I have easy access to slabs . cheap too. I cut them 4 ft and the idea is to push coals forward and add more slabs as needed. . The small pipe was going to be a fresh air intake using a small inline duct fan. Preheating air thru top barrel and feeding into the top front of burn chamber. Room temp air is fed by a small squirrel cage fan in thru the door via ammo can and( 2) 2-1/2 PIPES. I would appreciate a little more explanation. I don't have time or resources to start over. Once I get it burning and hot it burns clean out the chimney. Just alot of smoke getting to that point thank you
I ran foundries so was very familiar with metal oxide fume.
Occasional welding zinc coated pipe presents no real health risk.
Doing it every day of the week does because the poisoning is cumulative.
You need zinc to live it is in most muli vitiams.

Now to the furnace
the shape is all wrong for efficient burning which is why you needed to add the fans.
Only gasses burn so you have to gassify the wood using heat before it can start to burn
The process is called pyrolysis.
So you need to be heating the wood in the absence of available oxygen then adding oxygen to the gasses coming off the wood in order to get them to burn, it is a 2 stage process.
This is why good wood stoves have a primary & secondary air path in order to completely burn the gasses.
You get the best heat transfer from long lazy flames .
However flames naturally burn up not across which is why blast furnaces, cupolas & rocket stoves are all vertical not horizontal .

Your heat exchanger should also be vertical or at least at a 45 deg angle so the flue gasses flow under their own thermal forces and are not putting a brake on the flow of gas out of the oven
With your set up you are forcing the flue gasses to flow against the air you are pumping in unless you put a baffle in to keep the incoming fresh air apart from the outgoing flue gasses.

Look up as many wood stoves as you can that show a cross section of the combustion chamber
You will see all of them have at least one baffle to control the air flow inside the chamber .
The better more efficient ones will have several.

Toget good burning happening, you need a bed of ash & coals with little to no access to air so they burn very slowly.
Sitting directly on top of this bed is the fresh fuel and slighty higher up is the air intake so the incoming fresh air can combine with the pyrolysis gasses and burn with a long lazy ( yellow ) flame .
The better ones will divert some more fresh air into the flame zone so the flame can consume all of the pyrolysis gasses befor they get to the flue so you don't end up with tar & cresote build up in the flue & have extracted as much heat out of the combustion as possible.
 

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I agree with the warning that heating galvanized metal is a health hazard. I used flat, galvanized electrical box cover plates to fashion inlet draft control plates to replace the rotted ones on my small table top charcoal grill. Even outside the smell was sickening. I found myself lighting it everyday just to try and get it all burnt off. It took a couple weeks for the galvanized draft plates to stop putting off a perceptible smell. I knew the possible hazard from working in a foundry myself, but I thought on this small of scale, it wouldn't be an issue. I was wrong, I won't do that again. Besides, once the galvanizing is burnt off, the corrosion protection is gone. I only used them because they were cheap and the perfect size, not because they were galvanized.

You do great metal work! I burnt wood for years to heat my house and I now subscribe to the KIS principle, Keep It Simple. I used 6" black pipe to the chimney and 6" stainless steel pipe inside a masonry chimney. On the advise of a neighbor who grew up cutting wood when only hand tools were available for heating his home and cooking, I used a pair of adjustable elbows to put the black pipe going from my stove to the chimney on about a 45 degree slant with the exhaust flue damper installed in it. I put a magnetic thermometer with color indication on that pipe to help me get a feel for what works best. No stove will draft very well till all of its parts heat up. The greater the temperature differential between the exit gases and outside temp, the greater the natural draft. The colder the outside air temp, the greater the draft. If it was in the or lower teens outside, my stove would get incredible hot with the door (14" x 14") open for any length of time. That meant only opening the door long enough to put wood in and then close it and pinch up the inlet and the outlet flue dampers.

Judging by the heat coming off the 45 deg black pipe, I thought I was loosing a lot of heat up the chimney so with the idea of making things more efficient, I installed an upper " barrel type" heat exchanger above the stove and then put the flue pipe exit out the top of that. The flue pipe temperature was lower so I thought, ah ha, success, but the house was colder. Smoke would come out the door when I opened it to stoke it. I worked with it for a couple of weeks but couldn't get it to work as well. Even my wife complained the house is colder and smelled of smoke more.

One day, after having the door open for about 5 minutes trying to get the fire going better, I closed the door and headed upstairs. Before I could leave the basement, I heard a loud hissing that brought me back to the room just in time to witness the hissing culminate into a whoom! that literally blew the pipe off the upper heat exchanger, bouncing it off the ceiling! With gloves on, I was able to set the pipe back onto the opening to vent the smoke and got it shut down.

My father's generation used to talk about how coal furnaces and stoves would "peculate" and rumble. Even heard a story where several miners were gathered around a coal stove during a break to warm up, when their stove gurgled and then went, "wham", blowing the cast iron lid off the stove. Even though I was only burning wood, I figured something similar must have happened to me. I removed the upper heat exchanger and returned to my original, simpler set up. The house was warm again!

Even with the simpler setup, when first lighting my stove, smoke would come into the room if the door was open too far. But once going, the draft would easily handle the door being wide open, but that allowed too much air and the stove would get very hot. Once I had a chimney fire that my neighbor said the blue flame with sparks emanating from the chimney was quite impressive! The stainless chimney liner made it a non-event but still, I avoided future fires and checked the chimney every two weeks and cleaned if needed. I found there is a balance between how warm the exhaust gasses are and how much natural draft you have, one feeds the other. Too much heat taken from the chimney gasses, slows the natural draft, resulting in a cooler fire and more creosote in the chimney. I gave up on the more efficiency idea and went back to maybe wasting some heat out the chimney in lieu of better draft, better fire control, safer chimney conditions, a warmer, way less smokey house and a happy wife!

I worked at coal fired power plant and it had Induced Draft Fans (I.D.) that drew gasses out of the boiler through a network of heat absorbing apparatuses as well as Forced Draft (F.D.) Fans that blew air into the boiler. The FD Fans operated on maintaining a set oxygen level in the exit gasses to ensure combustion. The ID Fans operated to maintain the furnace at a slight negative draft to keep the gasses contained in the boiler and duct work.

I'm not sure how one can expect a natural draft to handle forced air injection without smoke finding it way out of any cracks. In the absence of enough natural draft, the stove and ductwork needs to be sealed up air tight and possibly enlarging the exit flue. The forced air fan would need shutdown to open the door and add wood and then restarted after the door is shut. And then if all that is successful, you would be creating foundry conditions which would require temperature monitoring to ensure none of the stove is melted or warped. After all that, I'm doubt that the electricity consumed by the fan(s) would be as efficient and economical as a simple natural draft setup would be. Just my opinion, I'll be curious to see how it goes, good luck.
 

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Zinc is not the problem. I worked in a brass smelter and on a bad day you could see 10' in the plant - it looked like a snow storm. Guys would get 'metal fever' and recover in a day or so. The real problem however, is cadmium, which is usually present. That's the stuff that will kill you. Or any lead, if that is present. I doubt you will listen to all the guys here who have said your setup is dangerous to your health, but, two things you can do are forget about the oxy-acetylene rig with a rosebud, take the firebox and flue outside and build a charcoal fire inside it - a BIG charcoal fire. You want to roast the whole thing hotter than you will inside the shop for a good long time. Let the fire burn for say a full day. That will clean off anything on the steel.

AS already belabored, you have a draft problem, as well as a configuration problem. The draft problem is causing your smoking (bigger flue needed). Not much you can do about the configuration at this point, but if you recall, your burn box is approximately the same shape as old time steam engines. The big difference is they had proper draft, you do not, so you can get your setup to work if you fix the draft issue. The fresh air should come in from one end and the exhaust gasses exit the opposite end at the top of the burn box.
 

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Found this, I've never looked into it before.
A stove would have to get pretty hot, steel will turn dull red about 1200 deg. I think.
Zinc doesn't become "toxic" at any temperature, but what does happen at the vaporization temperature of zinc (about 1600 ° F) is that the metal turns to a gas, such that it can be easy to inhale an overdose if you are a welder.
 

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//We built a stove out of a 120 gallon. Horizontal Air compressor Tank. We put a glav. Well casi g pipe down 8 inches Into The burn box. The top of the galv well casing pipe goes into the barrel heat exchanger . Then another piece of galv. Pipe Comes out the top of the barrel that connects to the flue. We have 14 feet of black stove pipe that goes up and out the roof of garage. Burns hot. We have two forced air fans pumpingair into burn box. It acts like it is starving for oxygen without the fans on. And it smokes out the fans and door until it gets really hot. I need good advice. //

I hope I am not readdressing what has already been said, but::
1) Where do you expect combustion air to enter when fans are not running?
2) Any Wood stove I have been around always had a grate to hold the burn off the floor and allow combustion air to flow up through the burn
3) Wis that well casing down 8" in the firebox. That should be the highest point? That by itself will cause smoke out the door when opened.
4) What is that little pipe out the front of the firebox supposed to accomplish?
5) The burn box must have a way to control entry of combustion air.Your fans seem to do that now(off/on) no in between.

Hopefully I understand your configuration and have not repeatedwhat has already been pointed out.
 

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Thanks for the reply.we have used galvanized well casing pipe for years for chimneys. never been sick. We didn't clean the tank. It was already Cleaned by the time we obtained it.yea, I kinda figured it doesn,t have enuff draw. I need to figure out how tocorect it. Now do you have and positive suggestions?
Possitive Suggestions: Air blowing in through door. You're on the right path with air going in BUT: take it off the door; it won't help with the door open, but I brazed an air tool fitting into the stack pointing in the desired chimney smoke direction. I put an airline right on it at 30PSI and like a spray gun, it creates a siphon effect. unless you have a "air in" under the door like me(which I closed and sealed with furnace cement because I have an auger ash removal system located under the cast iron grate that I made), there is nowhere to allow air to be drawn from the siphon effect, except OPENING the door. Now the smoke is being drawn INTO the stove! I put the air on BEFORE I open the door. It even works with the possitive pressure of the Oil furnace gun in the back of the stove to light large pieces of wood with the door open! I would not use a secondary heat exchanger if I had to do it again as it greatly reduces the the air flow which make the smoke come out when opening the door. It would be more efficient to put in another smoke stack and another stove. If I were you, I would work with what you already have. Please feel to ask me any questions about my oil fired wood stove. These are all the pics I could come up with and you can barely see the air tool nipple in the second part of brazed elbow(it's cheaper to braze a movable elbow than pay for a solid piece). My stove is amazing on a 10 degree day! No 4 hours to build up a "nuclear" bed of coals. The siphon effect is a real winner on an other wise terrible problem of the smell of smoke in the work place.
 

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I've used a small fan in front of the wood stove to induce a better dtaft,but if the chimney isn't drafting good to begin with this doesn't always help,like if its an outdoor masonary chimney,stone cold,that kills the draft until it warms up some and most likely the forced air blower will end up pushing smoke out of every possible "leak" around the door,etc..

I noticed using a forced draft once the stove gets going good,just makes the wood stove into an incinerator,and you'll be adding a log every 20 minutes to an hour depending on the type of wood--if left to draft by natural convection,the logs burn much slower but put out more heat,because your not just blowing the heat up the chimney with the forced draft..
 

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Found this, I've never looked into it before.
A stove would have to get pretty hot, steel will turn dull red about 1200 deg. I think.
Zinc doesn't become "toxic" at any temperature, but what does happen at the vaporization temperature of zinc (about 1600 ° F) is that the metal turns to a gas, such that it can be easy to inhale an overdose if you are a welder.

Go to your OH & S site and read up on Metal Fume Fever.
I ran a foudary so had to monitor the workers for Pb, Cu, Cd , Bi , Sn , Sb & Zn .
As oxides all of these are soluable if inhaled and end up concentrated in the kidneys & liver.
Mild poisoning appears as flue like symptoms &/or anemia which is how it got the name FEVER before we worked out what was actually happening.
All of them are reversable so the problem comes where the rate of injestion is greater than the rate of excretion which is both through urine & feaces .
The crunch is that rate has so many variables that the OH & S exposure rates are set very low.
Excessive amounts eventually cause renal failure .

Arc welding is a different case.
The actions of the arc cause the zinc to become an unnatural state Zn3+ in place of the usual 2+ and that is where the real problems occur.
You get Zinc Dioxide Zn2O3 . No metal vapour exposed to air stays a vapour for much longer than a few nanno seconds which has made proper chemical & molecular analysis of arc fume very difficult.
Arc welding also ionizes he air and every other thing in the air, it is a lot more dangerous than a lot of things which are demonized as KILLERS .
I did metallurgy for 10 years & I don't arc weld unless I wear a full leather jacket , long welding gloves & forced air mask.
I oxy weld bare handed with no PPE other than proper goggles .
Heating Zinc slowly as happens on a fire or oxy welding will cause the Zn to revert to ZnO which is not particularly dangerous
 
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