Discussion in 'Reverse Flow' started by gary s, Oct 13, 2015.

  1. inkjunkie

    inkjunkie Master of the Pit

    All this is assuming a round chimney, correct?
  2. This was figured on a round chimney 

  3. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Thanks Gary..... Thumbs Up ...

  4. Hey thanks for the point Bear, much appreciated 

  5. Hey, ink  I should have followed up better, sorry

    Square or rectangular tubing figures a little different

     (we will stick with the same tank volume 22,808)

    Let’s use the 0.0.20 which is 456

    Starting with 4”x4”   

    Divide 456 by   4x4   - (16)   which is 28.5 inch stack

    A 5 x 5 would be 18 ¼ inch stack

    A 3 x 6 would be a   25 1/3 inch stack
  6. You are welcome Dave, Haven't asked in a while how are you chickens, onions and garlic doing ?

  7. I dont like these formulas at all. A guy that has a two inch piece of pipe laying around will think he can use it on a 100 gallon tank as long as he makes it long enough, same with a guy with a piece of 10" pipe if he makes it short enough. But neither of those cookers will be worth a darn. A 100 gallon reverse flow works good with between a 4" to 5" pipe with a length within reason.
  8. The formulas are correct, But you have to use common sense, Like I said in the post and my email to my friend I think 4" is the smallest you should use, on average smokers  on Big smokers 250 gal and up you nee 6" pipe

    You sure don't want to evacuate all your heat and smoke with a giant stack as well as chocking down your smoker with a small long stack

    Me personally shoots for a stack from about 20 to 30 inches depending on the smoker, and like you said keep it out of your face

    I figure most people who build their own smoker have some skills and would know not to put a small 4 or 5 ft stack on their smoker.

    Also I didn't want to get to much more technical  but a small skinny long stack, besides restricting the flow allows the smoke and heat cool before exiting thus creating heaver air and further restricting the flow.

    Good to hear from you  How is the BBQ business ?

  9. inkjunkie

    inkjunkie Master of the Pit

    I think this is where being reasonable....and spending some time looking at others builds comes in....and perhaps asking a question or three.
    Thing for me is I have a very difficult time when someone just tells me do it this way because I said so and I know everything there is to know. Like most things in life there is more than one way to skin a cat.
  10. Kinda like everything, "Common Sense"   I don't think most people would put a 2 or 3 in stack on a 100 gal smoker, You can look at it and see right off that wouldn't work.  Like I said stick it up there step back and take a look.

  11. inkjunkie

    inkjunkie Master of the Pit

    Just of the ways to figure out the collector length on a race car header is to use an infrared thermometer. Where the temperature drops off is usually a good starting point, or so I have read. Can't help but wonder if this is true with a chimney. When I get a chance I am going to mess around with my infrared thermometer. Would like more in depth with my explanation but have to get moving....Sorry for the hijack...
  12. No Hijack

    I like it  be sure and let me know.   I have checked mine and the temp does vary at different levels.
  13. inkjunkie

    inkjunkie Master of the Pit

    Will ask one of my drag racing buddies for specifics on this and post what I find.
  14. Inkjunkie, in response to your remark. Please tell me how its any different to just tell you what size pipe you should use rather than using a fancy formula? Its all still based on experience of what usually works and what has not. One may "feel" more scientific to you, but its not.
  15. Hey Rib,  I need to add the 4, 5 or 6 inch stack to my post. To me , you and others who have built smokers it's kind of second nature, Like you said I wouldn't want a newbie to think it's OK to put 2 or 3 inch 5 foot stack on a smoker.   I have never used anything less than 4"   Because I know what works,  With the sive smoker we have built 4 and 5 in. is what we always use.

  16. Im just thinking it mau be easier to just give them a chart that says cc between this and this size should use pipe between this and this size? Maybe less complicated for the average joe.
  17. joe black

    joe black Master of the Pit OTBS Member

    Why is it that Joes always have to be average. Doesn't a Joe ever get to be above average?
  18. All kinds of Joes, we just talking about the average ones here.
  19. bearcarver

    bearcarver Smoking Guru OTBS Member

    Cheer up Joe!!!

    Never heard of a "Job-Joey" !!![​IMG]

  20. jckdanls 07

    jckdanls 07 Master of the Pit Group Lead OTBS Member

    But what I'm still confused about is where the percentage numbers come from.... percentage of CC .. you say you like to use 0.02... then you say Dave likes to use 0.022 .. you have all kinds of different percentage numbers in the chart... (grabs head with both hands on ears.. shaking back and forth... "I'M SOOOO CONFUSED" ) ,,, So your saying I can use any number I want .507 percent of cook chamber ... So confused I don't even know what I'm talking about now....

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