SMOKE STACK BASICS

[gary s]

Thanks Brian, much appreciated as always, Watching the Texas Tech game    Their Quarter back  Pat Mahomes  graduated from here in Whitehouse Year before last, Both my grandsons were a year behind him

Gary

 

[bdskelly]

 
Thanks Brian, much appreciated as always, Watching the Texas Tech game    Their Quarter back  Pat Mahomes  graduated from here in Whitehouse Year before last, Both my grandsons were a year behind him

Gary

LOL  Yes I am.  Dang Jayhawks are catching up... 

 

[JckDanls 07]

Smoke stack measurements are from the CC up ?... or from plenum up ?.. plenum is on end of tank 4-6 inches down from to top of CC

 

[swechef]

How about;
Stack length = approx 1/2 length of cook chamber
Stack Diameter= 1/5 diameter of cook chamber

Gives a good combination of looks and flow.

Now there's a nice rule of thumb. Taking the ratio between stack and CC volumes using Rib's Rule here yields precisely a ratio of 0.02 which is just what Gary advocates.

Of course it might sometimes prove difficult to find a pipe with 1/5 CC diameter but I would guess one can usually find something close. Also, it gives a hint on proper stack size also for smaller smokers, e.g. patio variants.

Thanks for the insights, this thread is great.

/W

 

[ribwizzard]

Thanks, Ive always used an unwritten formula something like;

CC shape should be like width should be about .35 length

Fire box width= CC width
Firebox height= CC width
Firebox depth= 4/5 CC width
Firebox to CC mounting height 1/3 CC.
And of course stack as mentioned above. Works good for me and sometimes I'll compare it to feldons if its a new size cooker just to see if im close.

Bigger cookers ill downsize the firebox some, and real small ones ill go bigger.

 

[Rafter H BBQ]

Gary, great thread & enjoyed reading it ! Very nice, sorry I'm so late !

 

[mosparky]

Gary, did you actually mean .02% or 2%.  The post reads both ways. Multiplying by .02 results in 2% which is where my confusion comes in. 

 I'm about to mod an ECB and was thinking about putting a short stack on it. At 16 inch dia and maybe 16 inches deep the volume comes to about 3,200 cu in. At 2% the stack volume is 64 cu.in. If I use a 2 inch dia stack, it needs to be 20 inches long. That certainly offends my sence of porportion. At 4 inch dia the stack becomes 5 1/8 inches long. better height wise but dang, thats about 1/4 of the smoker dia.

 If I go with the .02 % the stack volume becomes .064. That pretty much means drill a 1/16 hole in the lid and forget it.

 Really not trying to start something here, just want to get it right the first time.

 There is definately the possibility I screwed up the numbers. I did not write it out physically, just used the calculator and hoped to remember long enough to transpose it here. That and high school geometry was a long time ago.

 And the ECB may just be a beast aside from the typ smoker usually discussed here.

I would greatly appreciate a little help and clarity here ?

 

[gary s]

 
Gary, did you actually mean .02% or 2%.  The post reads both ways. Multiplying by .02 results in 2% which is where my confusion comes in. 

 I'm about to mod an ECB and was thinking about putting a short stack on it. At 16 inch dia and maybe 16 inches deep the volume comes to about 3,200 cu in. At 2% the stack volume is 64 cu.in. If I use a 2 inch dia stack, it needs to be 20 inches long. That certainly offends my sence of porportion. At 4 inch dia the stack becomes 5 1/8 inches long. better height wise but dang, thats about 1/4 of the smoker dia.

 If I go with the .02 % the stack volume becomes .064. That pretty much means drill a 1/16 hole in the lid and forget it.

 Really not trying to start something here, just want to get it right the first time.

 There is definately the possibility I screwed up the numbers. I did not write it out physically, just used the calculator and hoped to remember long enough to transpose it here. That and high school geometry was a long time ago.

 And the ECB may just be a beast aside from the typ smoker usually discussed here.

I would greatly appreciate a little help and clarity here ?

Here is what I did on my ECB

smoker_24.jpg

• gary s
• Oct 25, 2015

smoker_25.jpg

• gary s
• Oct 25, 2015

smoker_26.jpg

• gary s
• Oct 25, 2015

smoker_27.jpg

• gary s
• Oct 25, 2015

 

[racer102]

so if math is right then I have a 23.65 inch stack from the top of chamber using a 4" pipe

13508 cc X  0.022 = 297.198

0.7854 X 4= 3.1416 X 4 = 12.5664

297.198 divided by 12.5664 = 23.65

I plan on top mount so should I stick stack down in CC about 2"

 

[gary s]

 
so if math is right then I have a 23.65 inch stack from the top of chamber using a 4" pipe

13508 cc X  0.022 = 297.198

0.7854 X 4= 3.1416 X 4 = 12.5664

297.198 divided by 12.5664 = 23.65

I plan on top mount so should I stick stack down in CC about 2"

We  do,  it seems  to work well. Some folks extend it further and even down to the grate.

The smoker I use every week has the stack extended 2 in.   Works perfect

Gary

 

[barrelcooker]

I constructed this chimney extention today.

20151130_221503.jpg

• barrelcooker
• Nov 30, 2015

Comes out at grill grate level at the side of the smoker 2inch x2 exhaust

 

[ndhunter]

Can someone please help me with the math on this. I know I have 17600 cubic inches. My measurements are 50"hx22"wx16"d its a big rectangle lol. How do I convert the rest of the problem? if I go with the .02 formula I get 352 cubic inches. Please help before I screw something up lol!

 

[gary s]

 
Can someone please help me with the math on this. I know I have 17600 cubic inches. My measurements are 50"hx22"wx16"d its a big rectangle lol. How do I convert the rest of the problem? if I go with the .02 formula I get 352 cubic inches. Please help before I screw something up lol!

I replied to your PM  explaining  the formulas on figuring square, rectangular and round.

Hope this helps

Gary

 

[daveomak]

 

 
Can someone please help me with the math on this. I know I have 17600 cubic inches. My measurements are 50"hx22"wx16"d its a big rectangle lol. How do I convert the rest of the problem? if I go with the .02 formula I get 352 cubic inches. Please help before I screw something up lol!

I replied to your PM  explaining  the formulas on figuring square, rectangular and round.

Hope this helps

Gary

If you had explained those formulae on this thread, others could have learned also....

 

[gary s]

 
If you had explained those formulae on this thread, others could have learned also....

Hey Thanks Dave, I can do that.  I also need to finish my "Fill In"  Pit calculator   kinda got side tracked.

You been doing OK ?  How are those chickens ?

Gary

 

[gary s]

 
If you had explained those formulae on this thread, others could have learned also....

I'm sorry Dave, I guess I missed your intent,  I would be glad to help you understanding formulas.

If you have a specific question, just let me know.

Gary

 

[dstiltz]

Good thread . Three of the best minds on this forum giving insight. People who read it very carefully will learn a lot.

 

[meatbox]

Great thread... helped out when planning my stack.

 

[sausagefingers]

Hey there fellas, im sausage from Australia.

im just finishing my first build, vertical filing cabinet smoker with offset set FB.

i thinking a stack will help my top chamber heat. Correct?

my CC cu worked out at 20,000

I was wondering because my cabinet is 60 inches tall do i minus 60 inches from my stack height recommendation?

was thinking 4" id.

if you have instagram, this is what it looks like, called him Big Kev 



thanks guys this forum is rad

keep on keeping on