My build

Discussion in 'Reverse Flow' started by thahorrah, May 2, 2014.

  1. thahorrah

    thahorrah Newbie

    I can't add photos from my phone so I'll get them up tonight.

    Knowing that some have said that there are problems with the Feldon calculator, I still used that as the starting point for my build. It's a reverse flow obviously, made from 16 in pipe. The CC is 36 in long and the FC is 15 in long. The pipe, drip tray, and FC sides are all quarter inch. My opening between the chambers nets 21-22 Sq in. Exhaust pipe is 3 in.

    Here are some questions. The calculator gave me an exhaust length of 17 in. Does that sound right or should I be looking at longer? Also, when looking for temp gauges, what temp range should I be looking for for the FC? And where is the ideal place to locate the gauges?

    As I'm posting here, I'm obviously looking for input, advice, and compliments to boost my already inflated ego!😜 So thank you in advance!
  2. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    When using Feldon's, you want the FB to be 100% of recommended.... then the numbers are fine EXCEPT the FB/CC opening and area under the RF plate... add 50% to those figures..... Then you can make the FB any size you want but do not change any of the other numbers...

    Adjust the numbers for the exhaust stack so you get a length of 30-40 inches.....

    Chimney Size
    Enter the diameter of your chimney pipe to find out how long it should be.
    • A chimney that is too short may produce insufficient draft (drawing of air). A chimney that is too long may cause the air to cool before it exits, reducing effective draft and worse, dripping of exhaust materials onto food!
    • Many horizontal smokers have an exhaust between 30-40 inches in length, but there is no hard and fast formula.
    • If you are building a horizontal smoker with a vertical cooking cabinet, realize that the cabinet partly acts as an exhaust, thus you may greatly shorten the chimney.
    Last edited: May 2, 2014
  3. keny

    keny Fire Starter

    So, is the Feldon Calculator incorrect on the cooking chamber opening? I'm just starting a build. (still in the planning stage...)
  4. lendecatural

    lendecatural Smoking Fanatic

    The more I've looked into this issue, it appears the problem is "one calculator does not fit all". If you notice on the bottom of the Feldon's page, there are two smoker configurations. A simple offset smoker and a reverse flow. I think the numbers are fine for a standard offset; however, for a reverse flow the smoke/heat has to turn 180 degrees and exit from the firebox end. This doubles the air friction in the smoker and using the same size opening doesn't draft as well as may be needed. That's the main reason I see the "experience factor" used around here in the reverse flow thread to recommend 1.5 times the opening and area under the RF plate. A bunch of successful smokers have been built using the 1.5 factor. Stick with what Dave recommended and plan accordingly so when you finish your build, you will have less fiddling to do to get smoking!

    Good luck and keep us posted!
    Last edited: May 2, 2014
    keny likes this.
  5. Dave Omark, How come you haven't put together your own calculator? Make yourself famous?
  6. keny

    keny Fire Starter

    I agree! And thank you LenDecaturAL for the great response! I've now posted a new question about this, and my plans to build, so you guys can once again answer (most likely) the same questions you've been asked 2 billion times already...I'm sorry, but I just get tired of searching after a while! Thanks again!
  7. thahorrah

    thahorrah Newbie

    Here are the pics of by build as it stands now.
  8. radioguy

    radioguy Smoking Fanatic

    I was thinking the same thing!

  9. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    I put this together some time back...... Uses the CC to base all the numbers on.....
    I don't know how to do spread sheets..... used to, 20 years ago on a totally different system....

    Seems folks today don't know how to do much math so it's easier to crank out the numbers for them....
    Seems some have difficulty with how to interpret a drawing....

    One "fuzzy" part of the calculation..... As the CC gets smaller, add more area under the RF plate because the surface area to volume goes up.... on larger CC, 300-500 gallon, that number can get smaller for the opposite reason...

    Last edited: May 3, 2014
    coon8448 likes this.
  10. bryanmp9c

    bryanmp9c Fire Starter

    Ohh I like this idea.

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