Can't get temp over 150° on new pit

Discussion in 'Reverse Flow' started by cid79, May 22, 2012.

  1. cid79

    cid79 Smoke Blower

    I would really appreciate it if anybody had any ideas as to why I cant seem to get my cooker over 150° it has a reverse flow plate in it without any holes in the plate, I do not know what I am doing wrong, I just recieved this cooker and have been trying now for a couple of days to get it hot so I can season it, it has gas assist in the main cook chamber. The cooker is 4' long and 36" in diameter, with 24 x 24 firebox on it with the reverse flow plate inside.
  2. cliffcarter

    cliffcarter Master of the Pit Group Lead OTBS Member

    Is the exhaust stack on the same side as the fire box? Have you tried taking the plate out and then starting the fire? Can you post a picture?
  3. cid79

    cid79 Smoke Blower

    The plate is welded in place so I can't take it out i can put a picture of the smoker up but I haven't taken any of the plate yet I can do that tonight and post that tomorrow morning.[​IMG]
  4. cid79

    cid79 Smoke Blower

    No the plate can't come out it was welded in, I can take a picture of the plate tonight and post it tomorrow, but as far as my cooker goes I have a picture of it.[​IMG]
  5. cid79

    cid79 Smoke Blower

    No the plate is welded in place can't take that out. I tried putting picture up of it but it will go through, prob cause I and newbie here.
  6. cid79

    cid79 Smoke Blower

    I guess i can post pictures now. LOL
  7. Sounds like an air flow issue. From the picture your exhaust stack looks to small. I don't see your air inlet, but if you aren't getting enough air in there to the fire, it won't get hot either.
  8. cliffcarter

    cliffcarter Master of the Pit Group Lead OTBS Member

     You may be correct, using The CrankyBuzzard's workbook, I come up with a 5" diameter exhaust approx. 36" long, yours looks to be too small.

    Here's a link to the workbook, it may be helpful.
  9. jckdanls 07

    jckdanls 07 Master of the Pit Group Lead OTBS Member

    the firebox looks to be mounted up to high... the bottom of both the firebox and cook chamber looks to be even... where is the hole from firebox going into the cook chamber located ?
    at the bottom of the firebox ? maybe some pictures of the intake vent... the hole from firebox to cook chamber... whats the size of the exhaust stack ?

    If you look at any side firebox smoker, the firebox is ALWAYS lower than the cook chamber.. this allows for the hole between the two to be at the TOP of the firebox into the BOTTOM (under the reverse flow plate) of the cook chamber... look at those things and let us know
    Last edited: May 22, 2012
  10. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Cid, evening.... Looks like everyone has you covered......

    About the fire box.... Is that 1 .. 4" air inlet.... and 1 .. 4" exhaust ??  

    Here is another calculator to figure out what changes need to be made.....   Looks like a great smoker to me.... Just needs a little "tweaking" so to speak.....  Don't get discouraged.... lots of folks here with a TON of knowledge to help you make your smoker the best it can be.....  Try both calculators using your smokers dimensions etc. and bring on more questions.... 

    PS.... reverse flow plates do not have holes in them.... 

  11. cid79

    cid79 Smoke Blower

    [​IMG][​IMG]I thank you all for your help and input, you guys are very knowledgable, I believe you guy are right, I started a straight wood fire in it last night and the fire box got hot, then when I shut the door on it, it goes out, definetly a air flow problem, I am going to take ur guys advice and and move the FB down and larger smoke stack and I am going to add another air vent to the fire box, but I have pictures that I took this morning of the FB end. I will get dimension of everything tonight and post them tomorrow.
  12. bruno994

    bruno994 Master of the Pit

    No doubt, the firebox looks like it is way too high, but, I think if you increased the size of your opening from the firebox to the chamber, you would see a temp rise.  Also, you might need more air intake than the one you have, maybe add 1 more that size.  Between the small firebox to chamber opening and too little air intake, I can see why you are choking out your fire.  I would try these changes before moving the firebox down, sounds like a big project.  Refer to the above mentioned calculators, they will give you the numbers that you will need for proper air flow.  Good luck with your modifications and keep the questions coming.
  13. cid79

    cid79 Smoke Blower

    Who ever made the CrankybuzzardBBQworkbook.xls is genius, Thanks You for it.
  14. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Cid, morning....   Bruno has a good point.....  Leave the fire box until all other mods have been made....   and the air intake is too small...  enlarge the air intake according to the pit calculators ......   enlarge the opening to the cook chamber, enlarge it downward, toward the bottom of the cook chamber, according to the pit calculator...   I have attached a cool diagram for theory of smokers....  It explains quite a bit with pictures... 

    Great pics of your smoker.... it helps a lot in trouble shooting the problems you are experiencing.....  

    If you need help with the calculator, post here or PM anyone with your questions....   WE LOVE HELPING OUT !!!!!!! .... Gives us old folks something to do.... makes us feel like we are needed ...  Dave
  15. jarjarchef

    jarjarchef Master of the Pit OTBS Member

    I see a lot of post about the height of the fire box. I am working on the design and material gathering stage for my build. Where should the top of the fire box be in reference to the RF plate? I have seen post that the RF plate should be 4-6" below the cook grate, but nothing about how high the top of the fire box.
  16. bruno994

    bruno994 Master of the Pit

    Your firebox needs to attach at least high enough to your cook chamber to allow enough firebox to main chamber opening area to achieve proper air flow and draft  (based on this pit calculator)  .  My tank is 24" in diameter and rounded on the ends, not flat like yours Cid79, the bottom of my door is at the equator of my tank.  So I measured 4 1/2" down from center to mount my RF plate.  After doing the math to make sure of how much area I would need for proper air flow, it worked out where if I also cut out the semi-circle on the firebox end of my tank 4 /2" down from center, I would have enough area for the firebox to chamber opening.  This made installation of the RF plate quite simple as I just tied in the plate with the top of my firebox where it entered into the chamber.  At work I have some pics from  the construction phase, I will post them tomorrow to this thread when I get in.  Meanwhile, here are a few pics of the tie in of the RF plate and drip channel to the top of the firebox and an outside view of the firebox welded to the tank...Please excuse the grease accumulation on the RF plate, had a cook-off last weekend and have yet had time to clean it up!


    Last edited: May 24, 2012
  17. Ditto on what Bruno said, top of the FB even with the plate. Here's how I did mine.

    Think of it this way, the heat (thermal energy) from the fire is what you want to use to cook. To get the most out of your fuel, you want to do this as efficiently as you can so that you get the most energy using the least fuel. If you were to build so that the top of your FB was higher than the opening into the cook chamber, you create a pocket at the top of the FB. Heat rises so all that thermal energy in that pocket can't easily flow into the cook chamber. It will radiate out the top of the FB and be wasted.
  18. Look closer, I have two stacks side by side.
  19. bruno994

    bruno994 Master of the Pit

    Bubbonehead put that into words very well.  Here is the pic during construction of my pit.  Showing the leading edge of the top of the firebox, this is where the RF plate butts into.  Allowing for smooth flow of heat and air into the chamber, under the plate, and back around to the exhaust with no restrictions.  This is going to be the biggest problem with Cid79's build, is all the heat is going straight to the top of the firebox.  If the additional intakes and larger firebox to chamber opening doesn't fix the temp issues then dropping the firebox down will be a must.

  20. cid79

    cid79 Smoke Blower

    Good Morning everybody, I just got back from vacation, did a 220 pound hog that turned out awesome, not on my cooker on a friends, but anyways , I have taking care of the issuses with the firebox it is getting dropped, I got a larger diameter smoke stack, and I will be opening up the air flow from fire box to main cooking chamber also, and last adding another vent to the firebox so the fire can breath, and if I don't have to use it I can always clost it off.  I will post more pics when it's finished. Thanks for all the help.

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