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Author Topic: Baffled Smoker Chimney  (Read 1305 times)

Offline skigoldsboro

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Baffled Smoker Chimney
« on: December 11, 2020, 10:00:42 AM »
Bradley Smoker Baffled Chimney
By
Bob Szczepanski (12/2020)
   
Everyone that owns a Bradley Smoker and has read the manual, then used the smoker, knows wind and low temperature negatively affects the performance of the smoker, sometimes to the point where it isn’t useable.  Bradley even provides a warning to that effect.
To solve this problem many owners have tried to insulate the smoker, to little effect, or by simply replacing the undersized heating element with a 900 watt element. While effective, the element replacement is not so simple and requires what many consider major surgery.  In addition to that, it’s a rather brute force and pricey solution to an already expensive smoker.
After analyzing the smoker with an engineering eye, it became clear that in addition to the minimally sized heating element, the vent location and design was a significant (perhaps the most significant) cause of performance limitations.
My solution to the wind/temperature problem was to design a baffled chimney that would mitigate the effects of wind and dramatically increase the R value of the top of the unit, while still allowing full venting.  Inexpensive materials and fairly simple construction was also my requirement.

The design consists of a one gallon paint can modified to be a chimney with three internal baffles that sits over the vent on top of the smoker. Testing proved the design was effective in ambient temperatures as low as 25 degrees and greatly mitigated the effect of wind.

If interested in further details and construction info. contact me at skigoldsboro@gmail.com
« Last Edit: December 11, 2020, 12:14:41 PM by skigoldsboro »

Offline Edward176

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Re: Baffled Smoker Chimney
« Reply #1 on: December 11, 2020, 12:38:07 PM »
Great idea Bob. Do you have any pictures that you can post?

Offline Habanero Smoker

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Re: Baffled Smoker Chimney
« Reply #2 on: December 11, 2020, 01:07:36 PM »
Hi Bob;

Welcome to the forum. I hope you continue to post your tips and hints.


     I
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Offline skigoldsboro

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Re: Baffled Smoker Chimney
« Reply #3 on: December 12, 2020, 09:31:02 AM »
Great idea Bob. Do you have any pictures that you can post?
[/quote

I can't seem to post any pictures.  I have pictures of the chimney, baffle pattern and pre-heat tests.  Shoot me an email and I will reply with the entire article including pictures.
« Last Edit: December 12, 2020, 09:33:18 AM by skigoldsboro »

Offline skigoldsboro

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Re: Baffled Smoker Chimney
« Reply #4 on: December 12, 2020, 09:59:42 AM »
Here is the balance of the Chimney text:

Assembly:
I used the can cover to make a circle on scrap cardboard, drew in three one inch square tabs and cut line 5.25 inches from the bottom of the far tab. After three baffle pieces were cutout of the sheet metal using the pattern, the tabs were then all bent up at a 90 angle, completing the baffles.  I then divided the height of the can into four equal sections, which yielded a measurement of 2 7/8 inches.  Marks were made on the outside of the can at these intervals.  A 2 inch diameter hole, centered in the bottom of the can, which now will become the top of the chimney, was cutout using a hole saw. The upper most baffle was then trimmed to friction fit into the can 8 5/8 inches from the open end (former top) and parallel to it.  A hole was then drilled simultaneously into the can and tab on the baffle (eyeballing the tab location from the outside marks) while holding the tab in place with a small wood block to prevent the tab from bending while being drilled and to avoid drilling my fingers.  A small and short sheet metal screw was then installed, securing the baffle tab to the can.  This was repeated with the other tabs.  The next baffle was then installed at 5 ¾ inches with the flat side 180 degrees to the first, using the same method.  The final baffle was installed 2 7/8 inches from the bottom, again rotating the flat side 180 degrees relative to the second baffle. I now had a completed baffled chimney in less than an hour.

Performance:
Testing proved the effectiveness of the design.  In winds that were between 8 to 10 mph, with much higher gusts, at an ambient temperature of 48 degrees, it took the smoker 33 minutes to achieve an internal temperature of 281 degrees.  It took a total of 47 minutes to achieve 300 degrees.  Not bad considering the wind velocity and temperature.  Another test was conducted at an ambient temperature of 32 degrees.  Winds were light and variable in the 3 to 5 mph range.  It took the smoker 41 minutes to achieve 281 degrees. In either test, the stock heating element had no difficulty maintaining the set temperature once reached. Note that the biscuit heater was turned on in conjunction with the main element as a standard pre-heat procedure.

Design Overview:
The fundamental objective was to design an insulating wind resistant chimney based on a fully open smoker vent.  (While not test proven, the temperature/wind resistance should theoretically increase with a partially closed vent.)  Since the area of the fully open vent is approximately 3 square inches, that value was used to determine the size of the 2 inch diameter exit hole. (3.15 square inches).  Since noise reduction was not required, the standard open area allowed by the flat end of each baffle is approximately two times the vent area. Given the air volume and movement restricted by the baffles, the insulation value of the chimney is approximately the same as a standard 2 x 4 wall (between R 8 - R13). 

« Last Edit: December 13, 2020, 06:05:41 AM by skigoldsboro »

Offline TedEbear

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Re: Baffled Smoker Chimney
« Reply #5 on: December 14, 2020, 04:36:33 PM »
You can post pics if you host them on a free site and then click on the "Insert Image" button in a message. I'd like to see what this looks like.

Offline manxman

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Re: Baffled Smoker Chimney
« Reply #6 on: December 15, 2020, 02:31:16 AM »
Quote
You can post pics if you host them on a free site and then click on the "Insert Image" button in a message. I'd like to    see what this looks like.

Me too, interesting post.

Welcome to the forum skigoldsboro.  :)
Manxman

Offline skigoldsboro

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Re: Baffled Smoker Chimney
« Reply #7 on: December 15, 2020, 05:52:10 AM »
No magic.  It looks like an empty gallon paint can I bought at Home Depot for about $6 with a 2 inch round hole (cut in the bottom, now top) with the open end of the can placed over the smoker vent.  You can't see the three baffles inside the can. Each baffle is just a circle cut out from sheet metal with one flat side and three tab extensions added to the circle for mounting.

Offline Smoker John

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Re: Baffled Smoker Chimney
« Reply #8 on: December 15, 2020, 08:22:11 AM »
This is a very interesting idea, thanks for posting this. I wanted to add something that blocks the wind effectively this might be the ticket.
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