Downdraft SFB questions

Horizontal smokers with a side firebox and tuning plates.
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Wombat
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Downdraft SFB questions

Post by Wombat » October 24th, 2015, 12:57 am

I'm looking to buils a downdraft style SFB smoker. This is along the lines of a Jambo with the FB opening above the grate and the chimney below it. I have a couple of questions I need answered before I start buying steel

1. I'm looking at a CC that's 24" X 48" X 1/4". Can I get by with a single door at 45" or do I need to run with 2 doors at around 21" each?

2. is there any reason for most people putting the door flanges on the door rather than the inside of the CC opening. It would seem like a lot less chance of welding deformation happening if the flange was on the main body

3. I was going to run with Feldons calculations for the size of the FB/CC opening adding a 45o baffle to direct the heat upwards. Should I allow some extra clearance due to the restriction of the baffle eg 125%. I'm going to make the baffle a bolt on extra so I can play with tuning it.

4. I will be making the FB as a single skin (not insulated) and was going to 146% of Feldons calculations. (W24"x H22" X L 20"). Will this be a problem?

5. The chimney will be 5" square welded directly to the end plate with an opening cut out from just below the bottom grill, full pipe width for 6". The chimney will rise 32" from the top of the CC

Am I on the right track with these numbers? Any advice will be greatly appreciated. We don't get to see too many varieties of BBQ pit in Australia and I'm keen to give one of these a go. Is there anything else I should take into consideration?



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Rodcrafter
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Re: Downdraft SFB questions

Post by Rodcrafter » October 24th, 2015, 12:58 pm

One door is fine, you may want to put an counter weight on it to make it easier to open.
I put mine on the outside because it allows the largest opening and it is much easier to put on that way. I've never had trouble with warping but I use heavy steel.
I would recommend to you use the pit calculator on the home page of this web site. I don't have any experience on putting the baffle plate below the opening. However considering how heat works in an smoker, I don't see the 45* angle of the baffle being a restriction because the heat will be jumping over it anyway. So I wouldn't go bigger than 10% more than recommended on the size of the FB.
I don't make my smokers draft downward so I can't offer any experience on that.

Don't forget the pics.



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Current Smokers: Backyard RF Offset and Hybrid RF Offset trailer rig with Cowboy cooker and fish fryer, always room for more........

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Big T
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Re: Downdraft SFB questions

Post by Big T » October 24th, 2015, 7:55 pm

:yth:


Measure Twice.....Cut Three Times.

Brisket Envy
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Re: Downdraft SFB questions

Post by Brisket Envy » February 5th, 2016, 10:28 am

How did it work out?



BenzieBBQ
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Re: Downdraft SFB questions

Post by BenzieBBQ » March 14th, 2017, 11:21 am

Ya, how did this work out?



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