Vent Holes Vs Chimney

Discussion in 'UDS Builds' started by gacp, Jul 18, 2013.

  1. Hi everyone,

    I am in the process to make the final design of my first UDS.

    What do you think about chimney vs vent holes, which one performs better in terms of air flow and temperature control? And what sizes do you use?


  2. Hi Gustavo, I'm no expert so I'm sure someone with more experience could better answer this question, but on on the two that I have built, one had a two inch bung in the lid and one didn't.  On the one that did, I used about 18" of two inch black pipe that could easily thread into the bung that was there.  The other lid didn't have the bung, so I drilled 8 - 1/2 inch holes evenly spaced and in from the edge about where I wanted the heat to escape, about 1 1/2 - 2 inches in from the edge of the lid.  It's up to you, but the one I drilled I put 3 - 3/4" air inlets in and the one that had the bung I put 4 - 3/4" intakes in.  The one with the bung and 18" chimney and 4 air inlets can reach hotter temps for a little more versatility, but if your not going to go above about 300* I'm not sure it matters.  I would take what the lid of the barrel gives you, if it has the bung, go with the chimney, if not, drill some holes.  I hope this helps.
  3. fwismoker

    fwismoker Master of the Pit

    It's best to have a vent that can be completely shut closed for when you close down your pit or partially closed if it's super windy out.

    Some just use a pipe but that many times can't be capped or closed partially.  I've seen( 4) 3/4" 90 degree elbows around the outside that you can cap off to what mine has which is a Weber style vent.  
    Last edited: Jul 19, 2013
  4. noogsmoke

    noogsmoke Newbie

    For the pipe nipples on the bottom rim of the UDS i have read that almost everyone uses 3/4".  I have some leftover 1/2" pipe laying around.  Will the missing 1/4" make any sort of significant difference in airflow if I have a full chimney up top?
  5. fwismoker

    fwismoker Master of the Pit

    Use 3/4 for sure.
  6. Use 3/4  for bottom. and for your top. If you don't have a way to close it off after the cook.

    you won't be able to kill the fire and save your left over fuel.

    Happy smoken.


Share This Page