Horizontal stack/chimney?

[blakeman]

OK, so a stupid question.  I know we need a certain volume for the chimney, my question is, can the chimney run horizontally for a bit then vertically, or is it assumed for the air flow to work properly, the chimney needs to be vertical?

 

[forluvofsmoke]

No such thing as stupid question. Short answer: yes, horizontal before going vertical can work. The smoke chamber gases already are flowing horizontally across the pit, and by having a run of horizontal vent pipe, you are essentially extending the horizontal distance that it must travel before transitioning to vertical, which creates decreased draft due to the size of the space it flows through becoming much smaller, as well as distance. As long as the pipe diameter is sufficient, and the horizontal run is not overly long, or the vertical run too short, it should still have enough draft for proper ventilation of the pit. If the draft does not seem sufficient (difficult to build/maintain chamber temps being the most important, or obvious signs of stagnant smoke on the food), you can correct this by simply adding more height to the vertical run. If you have a planned long horizontal run, you may consider stepping up a size larger on the vent pipe to help improve the draft. Examples of successful long horizontal runs are home-built smokehouses with a fire box 10-20 feet or more away from the smoke chamber, useful for cold smoking...although this is for a smaller fire and not for hot smoking, it does work. The smoke house itself acts as the vertical section of the vet pipe...the taller the smokehouse, the more draft it will create. Also, you've seen those large trailer-mounted pits that are 30-40 feet long...that's a long horizontal run in itself, but they do have large diameter vent pipes and tall vertical stacks.

Eric

 

[ribwizzard]

Good answer!

 

[blakeman]

OK, great!  Thanks, -b