Flow problems with my custom build smoker

Discussion in 'Smoker Builds' started by metaldoctor21, Sep 27, 2013.

  1. metaldoctor21

    metaldoctor21 Fire Starter

    I painted it before I ever did a test run. I guess I should have waited to make sure everything worked first in case I need to modify it. I didn't want you to think I just painted it over the weekend even though it wasn't working properly.
     
    Last edited: Sep 30, 2013
  2. sqwib

    sqwib Smoking Guru OTBS Member

    I see smoke from the stack. That's a good sign. Any pics of the type of fire you had in the firebox?
     
  3. sqwib

    sqwib Smoking Guru OTBS Member

    smoke shouldn't be exiting the inlet
    I'm just reviewing your photos again
     
  4. metaldoctor21

    metaldoctor21 Fire Starter

    Just this one.
     
  5. sqwib

    sqwib Smoking Guru OTBS Member

    I think I see a potential problem in photo #1 although I would think this would be a minor issue
    Is there a piece of the firebox protruding from the top into the inlet?
     
  6. metaldoctor21

    metaldoctor21 Fire Starter


    It is part of my adjustable baffle plate from fire box to cooker.
     
    Last edited: Sep 30, 2013
  7. I kind of skipped through the thread and just read half the posts and looked at the pics, so excuse me if I repeat anything already tried,

    But that air intake/vent/baffle.....is it threaded in? Can you remove it?  If so, take it off and run the fire with the grate at the same possition as the last pic you posted above. From what I see, with good airflow, as long as your not loosing the heat from around your cooking chamber door, that thing should work.

    After removeing the vent cap, if it still doesnt come to temp, place a small fan blowing towards the intake and let us know what that does, if anything.

    Id like to see a pic of the fire too.
     
  8. metaldoctor21

    metaldoctor21 Fire Starter

    The intake baffle is threaded in. I will remove it and try to run it again with the grate above the intake hole.
    I have taken and blown air into the intake hole and it brings the pit right up to temp like it is supposed to.
    I am using royal oak lump charcoal and I usually start with one full chimeny of charcoal. Then I will put some wood chunks in. I will get some pictures of the fire for you guys.
     
  9. Well, with only one intake, that vent design might not be the best.
     
  10. This really seams strange.  Since we are trying different things, one more thought. I assume you have a drain pipe for grease, is it open or closed? The reason I asked on one of the smokers we built an RF unless the drain was open we experienced similar problems, open it up and it started drawing and heating like it was supposed to.   Just a thought

    Gary
     
  11. we need to get that to run with the grate at this level

    So as you have enough room for a decent fire. You might start thinking about how you would like to get air under the vent where its at. I can tell by your work your a tinkerer.
     
  12. metaldoctor21

    metaldoctor21 Fire Starter

    I have a ball valve on my grease drain, so I will give that a try. I also have a drain in the bottom and in the center of the fire box. Maybe I will open that up while it is running and see if that does anything to my airflow.
     
    Last edited: Oct 1, 2013
  13. metaldoctor21

    metaldoctor21 Fire Starter

    So your thinking get rid of one big hole and go with maybe two or three smaller holes spread out across the bottom as low as I can get them.
     
    Last edited: Oct 1, 2013
  14. sqwib

    sqwib Smoking Guru OTBS Member

    No keep that hole, Rib is saying to get air underneath your the fire, some folks will use a vent above the fire as well to give them better control off the heat.

    My grate is 4" above the bottom of my firebox and, with 2" holes, this leaves room for accumulative ash so it don't block the holes.





    Also a smoother transition into the cooking chamber helps.

     
  15. sqwib

    sqwib Smoking Guru OTBS Member

    That is the game plan, he moved the grate up as a test to see if it would draft better as the only inlet hole is above the fire.

    In one of the pics you can see smoke pouring out of the inlet.

    Rib, I think elongating the hole would help, oh and remove the baffle/damper thingy.

    I wonder if the heat is being trapped up at the top by the baffle or lip of the firebox, (refer to my firebox inlet pic)
     
  16. Here are some pic's of a Jambo build    Not mine !!                    You can see how high the firebox is mounted and where the openings are located




     
  17. sqwib

    sqwib Smoking Guru OTBS Member

    This has been driving me nuts... the more I think about it I have to lean towards the opening to the cooking chamber being the problem, especially after the test that was done by moving the grate above the air inlet and looking at my build and notes a hundred times.

    I have run mine with all vents closed with the exception of one and it still maintained a good temp and draw.

    If you close the air inlet completely, build a good fire on the grate at the level it was originally and leave the firebox door open...What happens?

    If it's still a problem with heat I would suggest the following.
    • Open up the cook chamber hole (remove the baffle thingy)
    • air intakes underneath the fire grate.
    With that done, If you are getting draft and everything appears to work with the exception of the heat being optimal I would suggest
    • Burning splits.
    That's where I would start.
     
    Last edited: Oct 1, 2013
  18. metaldoctor21

    metaldoctor21 Fire Starter

    If I build a fire, close the intake, fully open, partially open, or just crack the fire box door I lose all my heat and smoke out the fire box door.
     
  19. There is not much differential in height from your firebox intake to the cooking chamber opening. so I think its part of the problem getting a good draft going. Leaving the grate low and adding a vent to the bottom I believe may help. The air needs to run more verticle and get more rise inside the firebox to get a good draft going. Right now, its running almost horizontal,  and its not like you could put a check valve or anything to keep it flowing in one direction, all you can do is increase height differential.   You said when you put a fan there is came right up to temp......

    Sqwib, Dave, are all of the opening sizes up to snuff?
     
  20. metaldoctor21

    metaldoctor21 Fire Starter

    Here are some better pictures of my fire box to cooking chamber. I made the baffle just in case I needed to slow down some heat from the fire box. I also ran the two top holes into 2"x2" square tube that end about halfway into the cooker. My thought their was to try and move the heat further down the chamber to even it out. I wonder if this is also giving me poor flow or causing some kind of negative draw. I think I am going to do what SQWIB said and cut some of this out to open up the flow.
     

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