Small SFB upgraded

Discussion in 'Side Fire Box' started by mcguyver, Jan 2, 2012.

  1. mcguyver

    mcguyver Newbie

    I built this little smoker primarily to make smoked beef jerky. It is made almost entirely from stuff I had laying around.  My thinking was I only needed to maintain about 145F for a few hours fueled by large lump charcoal and hickory wood.  Easy enough..not so much.  The first batch I started the fire on charcoal and maintained it with hickory wood until the jerky was finished.  I thought the more smoke the better the flavor.  Again...not so much.  The smoke flavor was overwhelming and it was awful. One whiff and I felt I should drop on the ground and get below the stuff so I could breath.   I did a second batch using only charcoal and not wood.  It was alright but the smoke flavor was still quite strong.


    It is basically a tank that is 22" in diameter and roughly 36" tall.  It has a 20lb propane tank on the side for a fire box with a damper between the fire box and the smoke box. The firebox has it's own flue/vent and so does the smoke box.  The flue on the firebox has a damper that automatically opens when the damper between the firebox and the smoke box closes so the fire doesn't smother down.  The damper between the firebox and the smoke box is controlled by a PID to maintain what ever temp I set.  It works very well.  The heat comes in below the plate you see in the bottom of the smoke box and comes up all around it.  There is a pipe on the back of the smoke box with a blower that sucks the air out of the top and forces it in below the plate in a swirling motion.  It keeps the whole smoke box roughly the same temp top to bottom. 

    I decided that I had to have a source of heat that doesn't smoke to get my jerky dry without being too smoky so I added an electric element in the bottom of the smoke box below the plate.


    On the left you can see the inlet from the firebox and on the right you can see the pipe that returns the air from the top of the smoke box.  It is strategically located to cause the air to swirl around the tank.  This makes the all the jerky get done around the same time.   I did some testing today and with the ambient temp around 23F, the electric element alone got the smoke box up to 134F.  In warmer weather it will perform better. 

    I did install a second PID just for the electric element so 1 PID controls the damper between the fire box and the smoke box and 1 PID controls the electric element .

    I lit a fire in the firebox and set the temp on both PID's to 220 f.  It seemed to work perfectly.  The electric element pretty much stayed on and the fire box add a little more heat to get right up to temp and stay there. That will work great for smoking meat. 

    On my next attempt at making jerky I plan to get the smoker up to temp using only the electric element (obviously it will have to be warmer out for this to work) and then after the jerky has been in for a while I will start a fire and let it assist in drying the jerky.  Then I will just let the fire die out and finish on electricity.  Hopefully this will impart a nice smoke flavor without being so overpowering and I can do the whole process from start to finish in the smoker.

    Here is a picture of the control panel.  I haven't put on the labels or cleaned up the external wiring yet because it is still in the testing phase right now.


    That's a weather proof stainless steel box.  I had it laying around so reused it.  On the lower right you can see the solenoid that controls the cylinder that operates the damper between the firebox and the smoke box.

    Here is a picture of the flue damper on the firebox.


    When the damper between the firebox and the smoke box is closed it pulls on the cable and holds the fb flue damper open.  When the fb to sb damper opens, the spring snaps the fb flue damper closed.  This works pretty good to keep the fire good and hot.

    In short, a simple smoker can be more complicated than you think. 
  2. adiochiro3

    adiochiro3 Master of the Pit OTBS Member

    Wow.  That is complicated.

    I usually only lay about 1 - 1.5 hours of smoke on my jerky; the rest is just low heat or moving air for dehydrating.
  3. sprky

    sprky Master of the Pit OTBS Member

    Could it be the strong smoke flavor is due to non TBS, or stale smoke due to not enough vent. I honestly don't have a solution as I don't make jerky. 
  4. smokinal

    smokinal Smoking Guru Staff Member Moderator OTBS Member ★ Lifetime Premier ★

    Man you need an engineering degree to operate that sucker. I can see why you picked that screen name. It really is pretty awesome.
  5. mcguyver

    mcguyver Newbie

    The idea was actually to make it simple to operate.  Hopefully I can make a fire and just come by and add fuel when necessary.  We'll see if that theory holds up in practical use.  So far it holds what ever temp I set perfectly.  Now to get some meat and see how it works. 
  6. mcguyver

    mcguyver Newbie

    BTW Sprky, I was kind of wondering if I needed more ventilation.  I'm going to try making one more batch of jerky and see how it goes.  I just used the 1 1/4 pipe hole that was already on the tank.  I can easily cut a bigger hole and install a bigger flue.  The last batch of jerky I made in the smoker got done a little quicker than the dehydrator gets it done and I use one of those big box type dehydrators.  I think it is called an Excalibur.
  7. You need to run the exhaust wide open and regulate flow where the air enters the firebox only. You got stale smoke from it not flowing properly and maybe creosote too. You can't trap smoke and let it "soak" your meat. It needs a constant flow so the smoke it gets is always fresh. That's why your jerky was not so good.
  8. mcguyver

    mcguyver Newbie

    I put my info in the "calculator" and it says my firebox is undersized but I suppose I make up for it a little with the electric element.  It said that my smoke box flue/chimney needed to be 73 inches long at it's current diameter of 1.25 inches.  If I go up to a 2 inch flue I only need 23 inches long.  I think I will make that change.  My current flue is about 1/3 of the way down the smoke box.  Does having the flue down low contribute to the "stale" smoke issue?  Should I make an effort to move the flue up to the top of the smoke box?

    alelover, I don't have any kind of a restriction on the flue of the smoke box (other than it being small).  I do like the way you delicately described my previous attempts at making jerky.  "was not so good" is a great way to put it...extremely understated but great. :)
  9. mcguyver

    mcguyver Newbie

    2 days ago I got a chance to try another batch of beef jerky.  The little smoker worked flawlessly.  I absolutely love it.  You can adjust how much smoke your meat gets by adjusting the temp of the electric element verses the temp of the fire box damper control.  I got the smoker up to temp (145F) on electricity.  Then after the jerky had been in for a couple of  hours I started a fire using hickory large lump charcoal. After it was burning good (not smoking much) I turned on the damper control. I turned the electric element temp controller down to 142F and the firebox damper control at 145F.

    This made the firebox contribute more than the heating element After a while I bumped the element controller temp up to 144F and this made the firebox damper open less often and for shorter periods of time.  After about an hour and a half of the firebox contributing to the overall temp of the smoker, I just turned the damper off and let the fire go out.  I finished the jerky on electricity and it turned out fantastic.  It had a nice hickory smoke flavor with out being overpowering.  I didn't have to watch it that close because the PIDs kept the temp right on the numbers.  I did notice that the jerky closer to the outside of the smoker got done a little before the rest of the trays. Probably due to the fan swirling the heat around the smoker.   One trey didn't have any jerky near the edges of the trays and the whole tray seemed to come out done all at the same time.  I think I will have to experiment with the way I load the meat on to the trays but overall I thrilled with the performance. 

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