Throat size - Std offset vs. reverse

Horizontal smokers with a side firebox and tuning plates.
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SheffSmoker
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Throat size - Std offset vs. reverse

Post by SheffSmoker » June 24th, 2020, 5:03 am

Hello all,

Quick query on throat size - the calcs on here are for reverse flow design, should the throat size be the same area if constructing a standard offset as well?

I tried another set of calcs from somewhere else (might have been Feldons) and there's a 5 SQ IN difference in the size of the throat between the two. That doesn't sound a lot, but as this is a relatively small smoker it's approx 30% of the size difference.

Just want to make sure my sums add up before I chop the CC. Thanks. :)

CC: 2577 CU IN
FB: 1963 CU IN
Chimney: 98 CU IN
FB Air intake: 6 SQ IN
Throat: 15.7 SQ IN

The alternatice calcs use basic multipliers, so the throat is CC x 0.004 = 10.3 SQ IN. There's also a big difference in the FB air intake - CC x 0.001 = 2.577 CU IN as opposed to 6 SQ IN.



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Re: Throat size - Std offset vs. reverse

Post by mp4 » June 24th, 2020, 5:43 am

They are the same with size with this calculator.



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Re: Throat size - Std offset vs. reverse

Post by SheffSmoker » June 24th, 2020, 5:49 am

Thank you! :)



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Re: Throat size - Std offset vs. reverse

Post by Dirtytires » June 24th, 2020, 10:39 am

Don’t worry too much about the air intake as they can always be closed off. I always like the versatility of having a vent on each side of the firebox so one can be closed off completely if the wind causes issues. Being oversized means you can operate off only one vent.



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Re: Throat size - Std offset vs. reverse

Post by Zimbomike » June 24th, 2020, 11:34 am

Good day, I'm struggling as well reconciling different Throat size calculations. Below are the results from Smokebuilder Calculator

Cook Chamber 23.87 X 44 19690.08 in³ N/A N/A
Firebox 19 X 20 X 19 7220 in³ 6563.36 in³ 110 %
Chimney 4 X 19.78 249 in³ 361 in³ 100.24 %
Firebox Air Intake 2 inlets 36 in² 21.66 in² 166.2 %
Throat 57.76 in²

Now, using the factor of .004 I come up with 79.62, a variance of 22 in2. Way to big a gap to be happy with either figures...
Here is a link to the "Alternate" calculation site.
https://www.smokingmeatforums.com/threa ... st_1264161.
Any and all help is appreciated.



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Re: Throat size - Std offset vs. reverse

Post by Dirtytires » June 24th, 2020, 4:46 pm

You will find many different “calculators” and they are all a bit different in the results. You need to pick one calculator and follow it for the entire project. They all give different results and trying to confirm one result with another is just a nightmare.

I can’t speak for the other sites as I only used the numbers provided on this one. I do know that a lot of pits are built with the calculator here and, from experience, it works.

You have to decide.



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Re: Throat size - Std offset vs. reverse

Post by Big T » June 24th, 2020, 5:48 pm

:yth:


Measure Twice.....Cut Three Times.

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Re: Throat size - Std offset vs. reverse

Post by Pete Mazz » June 26th, 2020, 2:42 am

Thousands and thousands of pits have been built with the calcs here (and Feldons). They all work very well. WHy try to fix what ain't broke? :D


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SheffSmoker
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Re: Throat size - Std offset vs. reverse

Post by SheffSmoker » June 26th, 2020, 6:36 am

Pete Mazz wrote:
June 26th, 2020, 2:42 am
Thousands and thousands of pits have been built with the calcs here (and Feldons). They all work very well. WHy try to fix what ain't broke? :D
Just double checking the numbers as it's not an RF. The throat just seemed on the large size for the small smoker I'm making, but the calcs here and Feldon's both agree. :chef:



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