Exhaust?

Discussion in 'Reverse Flow' started by inkjunkie, Aug 18, 2015.

  1. inkjunkie

    inkjunkie Master of the Pit

    How deep in the cooking chamber? Not using a plenum. Went thru the edge of the compressor tank & partially into the dome. Have seen them drop in just a quarter inch. Have seen them dropped all the way to the grate. Confused how I should mount it.
     
  2. inkjunkie

    inkjunkie Master of the Pit

    If it is dropped to the grate level, does it get angle cut? How about drilling some holes in it?
     
  3. smokejumper

    smokejumper Smoking Fanatic

    Truth is, it makes little difference if any.

    The "high stack" folks warn against "stale smoke", however the smoke and heat are dynamic, constantly moving, so there is no possibility of stale smoke. There is no area in the cook chamber in which the air/heat/smoke is not moving.

    The "low stack" folks argue for maximum exposure of the meat to the smoke rather than letting it escape out the top before imparting its smoky goodness to the meat. In reality, there is only smoke entering the cook chamber. There are no static pockets of fresh air at grate level to ruin your cook.

    The important thing is to ensure your stack drafts well.

    Whether the stack is high or low, the same amount of smoke will pass pretty much uniformly through the cook chamber to create magic on your meat before it exits either high or low.

    JM2CW, YMMV
    Most folks who use a low stack at grate level cut it at an angle.

    I have seen some with holes.

    Either will work just fine.
     
  4. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    The closer you get to the food grate, the more it interferes with air flow to the exhaust.....
     
  5. inkjunkie

    inkjunkie Master of the Pit

    Thanks for the very detailed information.

    Thanks Sir. Wonder if it is a turbulence sort of thing or if it is just an obstruction?

    Once the Boss can wear a normal shoe on her right foot I will be zapping the chimney on. I do have another question but I need to find my clipboard with the numbers on it first....

    I will just be mounting the chimney with just an inch or so into the chamber....Thanks again folks
     
  6. I am a fan of higher stack placement

    This one was with square tubing, end mount



    This one a top mount extending 2 inches into cook chamber

     
  7. lemans

    lemans Master of the Pit OTBS Member SMF Premier Member

    Doesn't a Taller stack produce more draft?
     
  8. smokejumper

    smokejumper Smoking Fanatic

    Yes it does.

    However too tall of a stack will allow the smoke to cool too much decreasing the draft or killing it altogether.

    Insulating the stack helps in this regard.

    With the relatively small fires and low BTUs in a smoker, you don't need a rip-roaring draft, and the 30"+ length is typically good enough.
     
  9. inkjunkie

    inkjunkie Master of the Pit

    30"+? From the calculator found on this site...
    CC volume is 13860.
    13860x.022=304.92
    Exhaust diameter is 4"id.
    .7854x4x4=12.5664
    13860÷12.5664=24.26
    Wit this being under the 30" mentioned will I have a problem?
     
  10. No, You are correct in sizing your stack based on the cu. in. of your cook chamber.  I am a big fan of 4" that size seems to work great

    now that being said on large smokers 6" and 8" are needed  (really big smokers)  But all the backyard pits we build 4" is what we

    use.

    Gary
     
  11. smokejumper

    smokejumper Smoking Fanatic

    From Feldons:

      • Many horizontal smokers have an exhaust between 30-40 inches in length, but there is no hard and fast formula.

    Your stack will work just fine at 24.26"

    It will also work just fine a foot or so longer.
     
    Last edited: Aug 19, 2015

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