Reverse flow help

Discussion in 'Reverse Flow' started by dockman, Jan 18, 2015.

  1. dockman

    dockman Smoking Fanatic

    I built this for a buddy last spring. We are having problems getting over 250-275. The cc is 24" x 77", fb is 24", exhaust is 5" x 30", fb is mounted 8" up and reverse plate is same level, rf plate ends 7 1/2" from end. I have increased rf plate to cc end a few inches to about 9", cut a 2" x 3" slotted hole under fire basket in floor of fb, added 5" to exhaust, and bought some super dry wood. I get a good fire but not coals.
     
  2. dockman

    dockman Smoking Fanatic

    Here are a few pictures
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  3. dockman

    dockman Smoking Fanatic

    CC is 3/8" thick. It takes a good 1 1/2 hours to heat to 250. I also cut wood down to the size of little bigger then a beer can.
     
  4. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Below is a good air inlet design.....  Lower inlet below the fuel....

     
    Last edited: Jan 18, 2015
  5. dockman

    dockman Smoking Fanatic

    My thoughts also Dave but hen I cut the hole in floor right under fire it did not help any. Do you think I should increase the vent in floor to say 3" x 5" and make it adjustabe and then close off the tops of existing?
     
  6. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Under the fire grate....  about 30 square inches needed....  then the door inlet could be cut down to 4-6 sq. in.....    35 sq. in. is what's recommended for a smoker your size....  To fill the current intakes, tack a plate on the inside of the door so about 1" - 1.5" tall hole is there....  then it's not permanent..   Tack it tight to the door so there's no air leaks...


    Ribwizzard uses pie vents on the floor of the FB and has a pan to catch ashes and such...  place one near the front and one near the center of the bottom of the FB...
     
    Last edited: Jan 18, 2015
  7. dockman

    dockman Smoking Fanatic

    Thanks Dave that is kind of where my thinking was at. Glad you give me dimensions on bottom hole cause I was not thinking that big. Right now it is at the most 8 sq in.
     
  8. dockman

    dockman Smoking Fanatic

    Would vents on each side at bottom work?
     
  9. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Yep....   air under the fire grate, from the sides, works ....
     
  10. dockman

    dockman Smoking Fanatic

    Cut a 3" x 10" hole right under fire basket and plugged 2" (top side) of door vents. That done the trick cc temps peaked at 365. Thank you for the help Dave.
    [​IMG]
     
  11. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    That didn't take long to mod.... Now you've gotta make the 3x10 hole adjustable....
     
  12. dockman

    dockman Smoking Fanatic

    It is adjustable! I don't like the hole in bottom and may redesign the door with vents lower?
     
  13. dockman

    dockman Smoking Fanatic

    I own a welding shop.
     
  14. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    You want the upper air inlets ABOVE the fire so it will move heat into the CC.... WITHOUT adding air to the fire and increasing the heat....


    Did I not understand what you were planning.....
     
    Last edited: Jan 20, 2015
  15. dockman

    dockman Smoking Fanatic

    I would like to avoid 2 separate vents if possible. I do understand what you are saying. If i have to stay with upper/lower vents then I want them both on door end.
     
  16. orsmokerinaz

    orsmokerinaz Fire Starter

    Hello,  Just a follow up -  Listen to Dave.   I had several problems with temperature and control and getting temp even.   He knows his stuff.    I tripled the exhaust size and added the holes above the fire.   Whoa!  it really made a difference.   Now I can run from low to 300 if I want.  (Which I don't as I have a wood frame smoker).    Exhaust stays wide open and I control flow with upper vents and fire with lower.    The Mod was a real pain but it was worth it.  The example he gives for the FB door is a good start.   Gotta have the Air moving.  Good luck and happy smoking.

    BTW  Thanks again Dave!
     
  17. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Looking at your firebox, the basket is long and narrow..... the vent in the front and the one in the middle were suggested to get a complete and uniform supply of air to your fuel.... Air inlet near the door won't supply adequate air to the rear pile of fuel...

    Try to imagine the right side of the "damper set up" at the front edge of the bottom of the FB, and the hole on the left in the center of the bottom of the FB.... that is a good distribution of air to the fire, and the slide damper will regulate air to both locations.... making for a uniform heat from the fuel....
    The red outline is the slide damper..... adjust the dimensions for your particular needs...

     
    Last edited: Jan 21, 2015
  18. dockman

    dockman Smoking Fanatic

    Would this work? Can all holes be same sq in? One slider adjust top and bottom vents.
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  19. dockman

    dockman Smoking Fanatic

    [VIDEO][/VIDEO]Here is my redesigned door. Vent has been dropped 3" and added a divider to make bottom 3" x 4" and top is 3" x 2-1/2"
     
    Last edited: Jan 22, 2015
  20. dockman

    dockman Smoking Fanatic

    Forgot to add picture
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