Vertical Revers Flow Home Made -Temp Concern

Discussion in 'Reverse Flow' started by orsmokerinaz, Nov 24, 2014.

  1. orsmokerinaz

    orsmokerinaz Fire Starter

    Hi All - Just finished a RF as I was intrigued by all the press and how they smoke with "even" temps.   Well just finished and fired for first time.   Not real pleased with temps at the moment and could use some advice.   I'll post some pics but first let me say I decided to do a mix of wood, tile and metal to lessen the cost as I want to cook large packer cut briskets and store bought ones were too small - just did not work.   Custom ones were way beyond my budget but I now know why as it cost me a lot more than I estimated.   The Sides are 2x3's lined with tile board and skinned with aluminum.  Base of smoker is tile over tile board over steel plate.  Side channels to top are aluminum and pic shows where they come out.  Top is Tile, over tile board over insulation ~ 3" thick and skinned with Aluminum as well.    Fire Pit is 4" block on concrete with a large bbq burner for heat.  I have a 4" flue in bottom of box.  Box inside is 28" x 4" x 21" .  Firs t temp smoke run to test I had 200+ at top and 165 at bottom.    That was an hour run with some mesquite.   Now that is usable but I plan to do a longer run today as I need 225 and I would like more even temps.  My other smokers used a bottom opening and temps were similar but the hot spot was near bottom.   

    Suggestions -   Do O need to close some of the side vents to the top down a bit?   Everyone seems to say the only get 5-10 degree variance in the RF box.    Thanks 


  2. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    What size are the air/smoke/heat channels....

    I think that smoker will take about 6-8 hours to heat up before it draws well... There is a lot of thermal mass built into it...
  3. orsmokerinaz

    orsmokerinaz Fire Starter

    thanks for the reply -   The base smoke chamber with the fire is 16" high x 28 wide by 21 deep.  The side channels are 2" x 7.5 " and stop about 10" from top.    I just restarted it to do another run for temps.     I can easily cut a 12 x 12 from the bottom tile to allow the metal roof in the fire box to be exposed to the cook chamber or I can open a port in each of the side channels.  I wanted a lot of mass for the temp swings down here to stabilize but as I indicated I may have gone a bit overboard in the bottom of the smoke box.   If I remove a section of tile and cover with a steel plate I would think it may help the transfer.   ???

    OR Smoker in AZ
  4. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Does your design come close to mine.... My computer crashed and these are copies and won't enlarge.... sorry...

    Last edited: Nov 24, 2014
  5. orsmokerinaz

    orsmokerinaz Fire Starter

    Not too far off but can't read dimensions.    Mine is ~ 3 x 4 x 2.   A little smaller say 10 %.    Side Channels are 2 x 7.5.    My smoke channels are on the sides not the back.    I just did a check and with fresh wood and all vents open the temp is maxing out around 195.  Had it to 200 last night.  I think my BBQ side burner that I sued may be maxxed out.   Maybe need to get a harbor freight burner.   I think I'll get some lump charcoal and add it to see if I can juice it up a bit.   The bottom temp is near 170.   That's with a 1 1/2 hr burn.   Need to do brisket so I need the burner keeping it above 200 for sure.
  6. orsmokerinaz

    orsmokerinaz Fire Starter

    Just an update -   I managed to get to 213 which is more than adequate.  Took another 45 min and the xtra wood.   The bottom probe was over 180.  I backed the gas off a bit and after 15 min the top temp is 208 and bottom is staying around 185.    The temps are equalizing better but still 20 + variance.  I am going to give it another hour.  Then add some lump charcoal and/or a little more wood.   

    With the wood frame I am a bit nervous but I have tile board and aluminum covering everything.   Just FYI -  For what I spent I would have been better to go all steel and it would be a heck of a lot easier to build.   Hot smoking is really a different beast.   
  7. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Maybe you can right click on those drawings and save to a file in your computer, and enlarge them... There are no real dimensions on the drawings.... I was planning on the depth of the channels at about 2" or more... in a natural draft smoker, friction is enemy #1....

    The plate between the FB and CC was going to be 1/2" plate or thicker... a stable heat source for the CC....
    Last edited: Nov 24, 2014
  8. orsmokerinaz

    orsmokerinaz Fire Starter

    Well it looks like a bit of time to let the chamber settle down has really helped.  Temp will go to 240.  Issue now is getting it down to lower temps and keeping the dang wind from blowing out the burner.  Need to REALLY tighten the fire box door.  Will add rtv seal and maybe install a wind shield behind the door before getting to burner.  Looks like I can get temp to be stable at 180 now.    Since I do a lot of cold smoking I am not sure how I am going to get it down to the 100-125 range for fish.  Probably need to see what I can do with a smaller burner as I am at the lowest setting now for this burner.  I will try to throttle gas down at bottle but that is not a good thing either.

    The temp holds pretty well as i can shut burner off and it takes a "LONG" while to drop 20 degrees.

    I'll see if I can import the pics as well.   1/2 " is plenty of mass for sure.

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