Fire does not seem to burn (smokestack question)

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Sosolen

Newbie
Original poster
Sep 14, 2022
14
7
Hey guys.

I have a custom made smoker, I will put all the dimensions below as info, together with some pictures.

My question to you guys is, why I seem to have trouble keeping my fire lit with my firebox door wide open. When I keep the top door open, my wood burns crazy, but when I close it and keep the side door fully open, after about 1 minute my fire begins to smolder and the longer I wait, the thicker the smoke gets.. until it's just only thick white smoke and my fire has gone out fully.
Is it because my smoke stack is too small for the smoker? If I put it in the calculators, it seems like it is 7.5 inches too short, but that does not seem like THAT big of a problem, if I keep my firebox side open, does it? I mean, would 7.5 inches really mean I can't have a fire at all? Because of too low airflow?
Or is there another issue?

Important: I have removed the baffle plates and that actually gives me a much better left to right temperature, but does not help with the fire. From now on though, I will not be using those baffle plates anymore.

My logs are dry, I place my logs so that there is still enough air under it, I have a good coalbed ( tried with a chimney of charcoal aswell), but nothing works..

The smokechamber and firebox are made out of 3/8th inch thick steel, the chimney is made out of 1/8th inch steel.

Smoke chamber: 47.25x15.75 inch
Firebox: 23.6x15.75 inch
Smokestack: 27.5x3.15 inch
Side door opening of firebox: 7.9x7.9 inch
firebox opening into smoke chamber: 12x7.9 inch


When I use the basket, it seems to be doing fine, but I have a harder time getting higher temps+ have to use thinner splits + harder time keeping my ash bed big enough + have to always have everything FULLY open for reaching 250, barely.. So I would prefer to just be smoking in the bottom of the firebox
 

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SmokinEdge

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Poorly designed exhaust stack. You are not drawing through the chamber enough. When you open the top, you feed air and aid in exhaust at that point to the fire directly.

Remember you cannot draw anymore than you can exhaust. And those tuning plates are suspect as well.
 

TNJAKE

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Nov 26, 2019
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Poorly designed exhaust stack. You are not drawing through the chamber enough. When you open the top, you feed air and aid in exhaust at that point to the fire directly.

Remember you cannot draw anymore than you can exhaust. And those tuning plates are suspect as well.
I'm an American not an astronaut BUT I agree about the weird tuning plates. Choking out the natural airflow. I'd take them out and see how it runs. Bet it's a game changer
 

tbern

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If the calculations are showing 7.5" too short, try finding a piece to add onto your stack and see if it helps with the exhaust. Could use some thin stove pipe exhaust at first and if a certain length helps ( maybe even longer than 7.5") than find a heavier piece to match up with what you have on your smoker and attach those together.
 

tbern

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Totally forgot to welcome you to the forum, enjoy your time here! There are many on this forum who will be able to get your smoker working good!
 

JckDanls 07

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Are you building the fire on the bottom of the FB or is there a grate ??

I'm going to suspect your exhaust diameter is to small at 2.7'' ID... Thinking 4'' ID is what's needed...

Did you run your numbers through daveomak daveomak 's calculator ? It will tell you what size you need...
 
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Sosolen

Newbie
Original poster
Thread starter
Sep 14, 2022
14
7
Are you building the fire on the bottom of the FB or is there a grate ??

I'm going to suspect your exhaust diameter is to small at 2.7'' ID... Thinking 4'' ID is what's needed...

Did you run your numbers through daveomak daveomak 's calculator ? It will tell you what size you need...
Well, the calculators (if I see it correctly), they always ask for a diameter. So they don't suggest the width of the exhaust, only calculate how long it should be for what you have. You think extending it would help? or is that not enough?

I'm still really struggling with what will help more: thicker exhaust or longer exhaust.
 

Sosolen

Newbie
Original poster
Thread starter
Sep 14, 2022
14
7
Totally forgot to welcome you to the forum, enjoy your time here! There are many on this forum who will be able to get your smoker working good!
Thank you very much!

In regards to your previous reply, I will indeed try to find some extension piece and try it out.
 

Sosolen

Newbie
Original poster
Thread starter
Sep 14, 2022
14
7
Poorly designed exhaust stack. You are not drawing through the chamber enough. When you open the top, you feed air and aid in exhaust at that point to the fire directly.

Remember you cannot draw anymore than you can exhaust. And those tuning plates are suspect as well.
So how could I fix it? Extending the exhaust or do I have to make it bigger? If so, how big would you make it?
 

Sosolen

Newbie
Original poster
Thread starter
Sep 14, 2022
14
7
Ok guys, I just measured again and the smoke stack is 3.15 inch on the INSIDE (I have updated my original post according to this). It's currently 27.5 inch long (only 23.5 ABOVE CC)

I have ran the numbers on DaveOmak's calculater and it seems that it is the correct size...
 
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boykjo

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I have a question. What is this.
Captureash.PNG

This is not what you should have left over. All you should have left over is white ash. Fire managment should help with your situation. You need to reduce the size of your splits and they need to be dry as a popcorn fart. They should burn completely. Starter fire should be hot red charcaol then add small dry splits and they should catch fire and burn immediatley with no smolder.... My 2 cents
 

Sosolen

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Original poster
Thread starter
Sep 14, 2022
14
7
I have a question. What is this. View attachment 643680
This is not what you should have left over. All you should have left over is white ash. Fire managment should help with your situation. You need to reduce the size of your splits and they need to be dry as a popcorn fart. They should burn completely. Starter fire should be hot red charcaol then add small dry splits and they should catch fire and burn immediatley with no smolder.... My 2 cents
That bucket is still full from something else.. Nothing to do with my smoker, just happens to be standing there since I normally use it for leftover ashes.

It's full now since me and a friend of mine bought a second smoker and we did a big fire in it to clean it off. The firebox had a lot of leftovers from the previous owner, hence what is in the bucket on that photo.
 

chp

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Sep 30, 2020
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Colorado
That bucket is still full from something else.. Nothing to do with my smoker, just happens to be standing there since I normally use it for leftover ashes.

It's full now since me and a friend of mine bought a second smoker and we did a big fire in it to clean it off. The firebox had a lot of leftovers from the previous owner, hence what is in the bucket on that photo.
Welcome to the group. Hopefully you will able to get this issue figured out and start enjoying some great smoked foods. I would suggest removing everything you can from your smoker. Just have a basic shell. Place a simple grate in the firebox to allow the fire to breathe and get a fire going. Allow it to burn long enough with everything open to build a coal bed and bring all that metal up to temperature. Then starting at the firebox and working towards your exhaust, start closing doors. My guess is that all works well until that last door on the CC is closed. That just confirms your exhaust is not drafting like it should. Once you have confirmed the problem is at the exhaust stack, then I am sure the folks here will have some good ideas on redesign. If you are able to do the cutting and welding yourself, even better.
 
Last edited:

SmokinEdge

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First thing I would try is to remove the tuning plates, then I would start with a full chimney of red hot charcoal in the FB then one 2-3” split on top. This should be a nice hot fire. All vents wide open and see how the fire burns and how she draws. I’m also not sure about the coal basket in the picture, can’t really tell but this may be actually blocking intake air flow.
 
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Sosolen

Newbie
Original poster
Thread starter
Sep 14, 2022
14
7
Welcome to the group. Hopefully you will able to get this issue figured out and start enjoying some great smoked foods. I would suggest removing everything you can from your smoker. Just have a basic shell. Place a simple grate in the firebox to allow the fire to breathe and get a fire going. Allow it to burn long enough with everything open to build a coal bed and bring all that metal up to temperature. Then starting at the firebox and working towards your exhaust, start closing doors. My guess is that all works well until that last door on the CC is closed. That just confirms your exhaust is not drafting like it should. Once you have confirmed the problem is at the exhaust stack, then I am sure the folks here will have some good ideas on redesign. If you are able to do the cutting and welding yourself, even better.
Wow!! That tip on how to figure out what is wrong is (closing the cc last) is so simple, but I have not thought about that yet.. now I feel stupid 😂
I will definitely try that out! Thanks!
 

Sosolen

Newbie
Original poster
Thread starter
Sep 14, 2022
14
7
Ok guys, it was not raining today, so I tried out a new chimney size! I added about 19inch to my stack and tried again. Everything seemed to go really well! Apart from sometimes the logs that had to be arranged to catch again, everything went really really well. I even closed the door and only ran on the firebox intakes!!! (Never could have done that, always had the door fully open)...

It ran much more efficiently now. I just heard some sizzling with some logs.. They didn't smolder, but I think some were a bit too wet. I will have to buy a moisture meter to filter out the bad logs I guess.. But they are dry enough apparently, so it's not that big of a problem.

I think the issue is fixed by added some length to the stack. It was either adding length to the stack, or cutting it off and adding a whole new (wider) one... But I'm glad it's the first option, the easier one.

Here are some photos of todays run.


EDIT: By the way, I removed the baffle plates and my smoker is really even from left to right, it's crazy! The baffle plate actually fucked up a lot of things.
 

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Sosolen

Newbie
Original poster
Thread starter
Sep 14, 2022
14
7
Good to see you got it working better.
Looks like you fixed your grey chicken issue also
Yes, I think the baffle plate had a lot to do with it.. Will wait until 2 more cooks before confirming it's fixed though...

EDIT: Or maybe the improved airflow fixed it.. Who knows