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Converting from single pass to reverse

Discussion in 'Reverse Flow' started by aero-q, Sep 2, 2010.

  1. Hello all my new found friends!  I am new to this site, and fairly new to smoking.  let me introduce myself.  I am a mechanical engineer and the general manager of a wind tunnel where we test NASCAR cars and trucks...officially the coolest job in the world!  I am pretty mechanical, can weld and have accress to a great machine shop and fabrication "stuff".  I just completed my first horizontal smoker.  It's a single pass, 31" dia and 52 inches long.  I built the trailer and the whole shootin' match.  it cooks OK but, as with so many single pass, I am having too hard a time controlling the heat across the entire cooking surface.  Not really interested in messing with addition of tuning plates and all that.  After about a dozen cooks so far, I have mde the big decision to CONVERT the unit to a reverse flow.  I will keep you all in touch and will definately be asking questions along the way.  I am also about to begin building my first UDS.  Actually gonna build two and give to a friend as a wedding gift...what a great gift that would have been for me!
  2. mballi3011

    mballi3011 Epic Pitmaster OTBS Member SMF Premier Member


    First off welcome to SMF there aero-Qer. You sure do have the coolest job I used to watch the races all the time. Now it's more about cooking/smoking and such other things. It sound like you know what you want with your smoker so enjoy this site for It's the coolest/best site on the web for real. So go get something to smoke and we will be here if you need any help.

    Welcome To Your New Addiction.
  3. Ok, so here are my first 2 questions.  A little background;   The smoker is 31" diameter x 52" long with flat ends.  I have used the smoker calculator for everything except firebox size.  Mine is 20% the size of the entire chamber...not 33% like the calcs suggest.  Air inlet to the firebox consists of 3 "slider" openings totaling 27 sq inches.  firebox outlet to the chamber is 3x21 = 63 sq inches.  chimney is 6" sch. 10 pipe (sprinkler pipe) with an open aera of 31 sq inches x about 18 inches long.  Will; have a sliding extension on inside of smoker to lower the stack inlet down to near the cooking grate as needed.

    question #1;  Can someone advise me of the correct opening size between the end of the baffle plate and the smoker end wall (opposit the firebox end)?  I need total sq inches to preven stale smoke phenom.

    question #2:  Is there an optimum or recommended distance be between the cooking surface and the baffle plate.  My current design is leaning towards 4".
  4. 2bears

    2bears Smoke Blower


    Hey, can I be your friend that is married too? (would love to get that for a gift, dude you are alright ! )

    This will be a good thread to follow as I am going to build a rf 250 on a trailer this winter.
  5. sqwib

    sqwib Smoking Guru OTBS Member

    Just be careful if you mount the firebox into the smoke chamber, you will get a ton of convection coming off the top of the firebox into the chamber...trust me I have learned that the hard way.

    If its already mounted I would run your reverse flow baffle over top of the firebox and not connect to the side of the firebox....if that makes sense?

    Maybe others can confirm this.

    Meanwhile her is a link to the..

  6. work on the conversion will have to wait a bit.  Leaving for Cancun for a week with my wife.  its our 25th anniversary :)  We'll talk when I return
  7. OK...I'm back from vacation and ready to get to work.  I gotta hurry because I have to finish the conversion and give it a test run ( or three) before I cook for over 100 parents and students at an Appalachian State game in November.  Also going to Talladega race at end of October.  Whew, busy time coming up.  I'll try to keep progress pics posted.  Tomorrow night I plan to make headway on installing the 1/4" baffle plate.
  8. tom37

    tom37 Master of the Pit OTBS Member SMF Premier Member

    My grate is about 4 inch's or so. If I remember corectly I made the end of plate opening not quite as large as the fire to cook area opening. I planned to have it the same size but due to an error in math it ended up a little less on the sq inch's.

    Man 31 inch's across the grate is an awesome size, Can't wait to see the progress pics.
  9. Whew, what a day.  Installed the main plate and stack today.  MANY feet of mig weld.  I took a bunch of pics and hope to post them tomorrow.  All that's left is to re-install the upper rack support arm and modify the length of the upper cooking grate to fit between the supports.  Maybe a couple hours of work.  Then paint the modified areas with high temp paint...also tomorrow or Friday.  Should be able to bring her home this weekend to season, fire and test the temperature distribution.  If all is good, there are a couple of briskets in my near future!
  10. Hey Aero-Q,

    I live in Mooresville and I am in need of someone to do a little sandblasting. Given your line of work do you know anyone that would help out a fellow BBQ'er? I have a 250 gallon propane tank build that is about 50% done and I need the small amount of remaining paint stripped off.

    Thanks! Can't wait to see your pictures!
  11. [​IMG]

    New 1/4" heat plate and ends being fir and tacked.  Firebox is on Right hand side.  Smoke/heat "turnaround" on Left end


    Weld-out.  Seal welded all around.  New plate and ends will hold up to 18 gallons of water.  Outlet drain shown just above the brick.  The other drain (with the cap) is a drain for the tank below the plate...just in case of a leak :(


    Smile !  [​IMG]


    New 1/4" end plate covering area where stack used to exit...you gotta lova a MIG welder!


    Fit and Tack of 6" stack.  I use schedule 10 sprinkler pipe


    Stack extension sleeve to control location of heat and smoke outlet


    Ready to mount her back on the trailer.  Besides a MIG welder, you gotta love a good forklift!


    Back on the trailer!

    Will upload a couple more pics after I re-install the prep table and water outlet pipe, valve, etc.  Will also add a before and after modification pic
  12. dave54

    dave54 Smoking Fanatic

    is it going into the wind tunnel for a test run?

        Nice smoker! 
  13. When I built my smoker I searched the Mooresville area pretty hard for sand blasting.  EASY to find many with all the races shops here.  The problem was that so many didnt want to do a small job, and their quotes reflected it!  I had three different quotes with three widely ranging prices.  the lowest quote was from a gentleman named Ron Bergman.  He owns the business.  Its small and he's willing to do any size job for a buck.  Also owns all his own equipment.  He does either either sand or soda blast.  I recommend soda blasting.  It's eco-friendly and leaves a better surface finish for painting.  That said, I had to use sand blasting because of the heavy pitting inside the tank I used (it used to be a boiler condensate water tank).  Anyway, the name of his company is Lake Norman Soda-Blasting.  number is 704-517-4738.  Tell Ron the guy at the wind tunnel sent you!  For reference, it cost me $150 for mine (not the trailer).  Took him 2 hours.  Another word of wisdom:  Be ready to prime and paint as soon as he is finished blasting.  If you don't, flash rust will take over in a matter of a day or so.  Especially with our humidity around here.

  14. I promised a before and after picture.  Here ya go:


    Before....as a single pass


    Now...as a reverse flow.  Note the addition of a the 1 1/2" drain valve.  The new heat plate has been designed to hold up to about 18 gallons of water if I choose to cook that way.