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Science behind smokestack size?

Discussion in 'Wood Smokers' started by fourthwind, Sep 5, 2009.

  1. cmayna

    cmayna Master of the Pit OTBS Member SMF Premier Member

    Is that formula only for a certain type of smoker such as a charcoal one?  What about Electric and propane smokers?
     
  2. cmayna

    cmayna Master of the Pit OTBS Member SMF Premier Member

    Question:  Does type of smoker (charcoal, propare, electric, etc)  dictate different forumlas?
     
  3. ccjammer

    ccjammer Newbie

    ccjammer here,i have a 20 inch x 48 inch long cooker with a  18 x 20 square fire box offset

    it has a 3 inch dia. x 30 inch long stack on the side top and was wanting to replace with a 4

    inch dia. that is 4  foot long,is that sufficient enough or do I place it towards center of pit,any

    .answers will be very appreciated. 
     
  4. ccjammer

    ccjammer Newbie

    ccjammer here,i have a 20 inch x 48 inch long cooker with a  18 x 20 square fire box offset

    it has a 3 inch dia. x 30 inch long stack on the side top and was wanting to replace with a 4

    inch dia. that is 4  foot long,is that sufficient enough or do I place it towards center of pit,any

    .answers will be very appreciated. 
     
  5. ccjammer

    ccjammer Newbie

    ccjammer here,i have a 20 inch x 48 inch long cooker with a  18 x 20 square fire box offset

    it has a 3 inch dia. x 30 inch long stack on the side top and was wanting to replace with a 4

    inch dia. that is 4  foot long,is that sufficient enough or do I place it towards center of pit,any

    .answers will be very appreciated. 
     
  6. ccjammer

    ccjammer Newbie

    ccjammer here,i have a 20 inch x 48 inch long cooker with a  18 x 20 square fire box offset

    it has a 3 inch dia. x 30 inch long stack on the side top and was wanting to replace with a 4

    inch dia. that is 4  foot long,is that sufficient enough or do I place it towards center of pit,any

    .answers will be very appreciated. 
     
  7. ccjammer

    ccjammer Newbie

    cc jammer here

    ,

    i have a 20 inch x 48 inch long cooker with a  18 x 20 square fire box offset

    it has a 3 inch dia. x 30 inch long stack on the side top and was wanting to replace with a 4

    inch dia. that is 4  foot long is that sufficient enough and do I place it towards center of pit,any

    .answers will be very appreciated. 
     
  8. pootin pig

    pootin pig Newbie

    Trying to determine exhaust stack size. I'm wanting to do dual stacks. I've taken an old pig cooker that is 60" longX30" deep, and 30" high. I built a firebox that is 24x24x30 with an opening that is 30x 51/4. The firebox is mounted on the lower back of the cooker and I have a plate inside of the cooking chamber to spread out the heat. I want to do dual stacks on the top at the rear corners. the only calculators I found give you single stack only. I'm thinking like 2- 3" stacks around 32" tall should do it. What do you think???????? Would that be the same as 1- 6' stack?
     
  9. daveomak

    daveomak Epic Pitmaster OTBS Member SMF Premier Member

    No... not the same....   actually exactly half the size needed....   4 - 3" stacks would be the same...  I would go with 2 - 5" stacks...
     
  10. bitterroot mt

    bitterroot mt Newbie

    I know this is a old thread but based on the 15%

    and 1/3 theory

    if my tank is 92 Long

    it is 38 wide

    My stack should be  6in wide and 31 Tall.

    I am building a firebox from 2 55 gallon drums w with doors at either end like drum stoves.

    23 wide 70  long

    I realize it is a little undersized .... all I could scrape up.

    .

    2  6 inch inlets between the firebox and cook chamber .

    Set up like a diamond plate Pit Mod.

    Anyway.. Could I use   two   3 inch or 4 inch stacks  with dampers.on this and mabey a little shorter   say 24-26 inches tall

    and be ok ..

    MY thought is that it would hold in heat longer and  still let out the correct volume.... am I correct here?

    Thanks
     
  11. daveomak

    daveomak Epic Pitmaster OTBS Member SMF Premier Member

  12. I used to heat my house with a wood burning stove and from all I read and learned, the draft effect of the chimney is caused by heated air being less dense (lighter) than cold air.  The heated air in the flue therefore rises, inducing (pulling) cooler air into and through the heating chamber.  Since the heated air rising up the flue is gradually cooled by contact with the flue, I guess it's possible that if the flue is too long, the heated air will drop to the temperature of the ambient air, thus eliminating the draft effect.

    Conversely, if a fan is used to force air into the heating chamber, as with a BBQGuru or similar system, then it wouldn't matter if the flue gas is too cool to induce draft through the system.

    My guess is that the optimum length for a chimney on a smoker will vary with the ambient air temperature.  That is, during hot summer days, longer flues can be used.  But on very cold winter days, a long flue may result in too much cooling and reduce or eliminate the draft effect.
     
  13. Ron Burg

    Ron Burg Newbie

    Looking to do a vertical smoker.
    50 high x 23 wide 18 inches deep.

    Do I need 2 smaller stacks on each side...
    1 larger one in back
    Ranger uses no stack, on one model just open vent in bac k.

    Thanks