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FB placement relative to CC (offset vs. rear or under mount)

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1215

1215

Fire Starter
Original poster
Feb 22, 2017
70
17
Using 35gal drum for FB and 55gal drum for CC. 

I like an offset because it's easy to have a warming tray/griddle surface and the FB door opens away from CC lid. On the other hand, an attempt at even temps across the CC is the biggest priority in this build. 

Does anyone with a traditional RF offset have CC temp numbers across their CC, or at least one above the FB and one at the far end?

Thanks. 
 
loutoo said:
firebox end is 50 degrees hotter than the other end.
Click to expand...
Thanks a million. That's exactly what I'm worried about. I want even across the whole CC. Any suggestions?
 
Install a horizon type convection plate. It should have a row of small (3/4") holes near the firebox and rows of increasing size, up to almost 2" at the opposite end. The plate should run approximately 3/4 of the whole CC. The increasing hole size will allow more heat and smoke as you get farther from the FB. But, the farther from the FB, the heat will be going down, so the overall should average out. My CC is 48" long and the temps are within 10* from end to end.

Good luck with it. Joe. :grilling_smilie:
 
Joe Black said:
Install a horizon type convection plate. It should have a row of small (3/4") holes near the firebox and rows of increasing size, up to almost 2" at the opposite end. The plate should run approximately 3/4 of the whole CC. The increasing hole size will allow more heat and smoke as you get farther from the FB. But, the farther from the FB, the heat will be going down, so the overall should average out. My CC is 48" long and the temps are within 10* from end to end.

Good luck with it. Joe. :grilling_smilie:
Click to expand...

Joe, it's a RF: it's got to have a plate already in to redirect the heat and smoke flow. Another ventilated Horizon style plate won't do any good imho. There's got to be something goofy going on. Lou, is your RF plate solid or perfed? Floating or welded in place? That heat is somehow bypassing the plate and entering the CC somewhere....
 
This is just a guess but having done quite a bit of welding (never built a smoker though), I'd say that the heat transferring through the metal on an uninsulated FB is going to be high. With an offset, or really any FB directly welded to the bottom of the CC, unless you get really creative with insulation you are going to have a lot of heat transferring through from the frame of the FB to the frame of the CC. That will make a hot spot. 

I'm trying to come up with a single, or double RF design that either takes advantage of the FB hot spot --or a single/double RF design that isolates and insulates the FB but distributes heat evenly throughout the CC. 

Other thing I'm thinking about is with the FB welded direct to the CC (no chimney in between), it's easy to change the hot-spot & FB temps (make fire hotter) quickly but far end's temps will change very slow. On the other hand, if I isolate the FB from the CC, I'm pretty confident that I can come up with a design that will make the temps fairly even across the whole CC (goal is less than 5-degree difference) but the CC's temps will change/rise much more slowly as it will be a much more indirect heating method. 

I just don't know enough about smoking to know what I want or what is considered ideal... Anyone have a few words of advice? Thanks. 
 
1215 said:
 
This is just a guess but having done quite a bit of welding (never built a smoker though), I'd say that the heat transferring through the metal on an uninsulated FB is going to be high. With an offset, or really any FB directly welded to the bottom of the CC, unless you get really creative with insulation you are going to have a lot of heat transferring through from the frame of the FB to the frame of the CC. That will make a hot spot. 

I'm trying to come up with a single, or double RF design that either takes advantage of the FB hot spot --or a single/double RF design that isolates and insulates the FB but distributes heat evenly throughout the CC. 

Other thing I'm thinking about is with the FB welded direct to the CC (no chimney in between), it's easy to change the hot-spot & FB temps (make fire hotter) quickly but far end's temps will change very slow. On the other hand, if I isolate the FB from the CC, I'm pretty confident that I can come up with a design that will make the temps fairly even across the whole CC (goal is less than 5-degree difference) but the CC's temps will change/rise much more slowly as it will be a much more indirect heating method. 

I just don't know enough about smoking to know what I want or what is considered ideal... Anyone have a few words of advice? Thanks. 
Click to expand...
1215, a well-covering baffle and tuning plates should get you to about a 5-10 degree differential without a lot of effort.  I like these better than fixed RF plates, as I can adjust them as I want to on the fly (tacked in RF plate doesn't allow that latitude), can have temp differentials if I so choose for something that I want done hotter and faster, and makes cleanup underneath much easier vs. an affixed plate.  Also, a baffle that fully covers the inlet from the FB and fully redirects the heat/smoke underneath the tuning plates is critical:  often this is where the culprit resides, as the baffle only partially covers the inlet and heat/smoke escapes out and around it.  My $0.02
 
gr0uch0 said:
 
1215, a well-covering baffle and tuning plates should get you to about a 5-10 degree differential without a lot of effort.  I like these better than fixed RF plates, as I can adjust them as I want to on the fly (tacked in RF plate doesn't allow that latitude), can have temp differentials if I so choose for something that I want done hotter and faster, and makes cleanup underneath much easier vs. an affixed plate.  Also, a baffle that fully covers the inlet from the FB and fully redirects the heat/smoke underneath the tuning plates is critical:  often this is where the culprit resides, as the baffle only partially covers the inlet and heat/smoke escapes out and around it.  My $0.02
Click to expand...
I really appreciate it. That makes a lot of sense. I guess I should rephrase my concern/goal as not being 100% even and consistent all the time --I just want control of temps across the whole CC. It would be nice to have the ability of even temps across the CC just as other circumstances to (intentionally) have one section a little hotter, depending on what is in there. So thanks very much. That's a huge help!

Next question... All the photos of tuning plates I've seen have been very manual. Manual to the point that you have to lift up the cooking grates and slide them. Is this something I should spend more time researching? I was thinking about this in terms of making vent ports in the RF plate, similar to an air intake slide at the FB. But that would get all gunked up in a hurry... 
 
1215 said:
 
I really appreciate it. That makes a lot of sense. I guess I should rephrase my concern/goal as not being 100% even and consistent all the time --I just want control of temps across the whole CC. It would be nice to have the ability of even temps across the CC just as other circumstances to (intentionally) have one section a little hotter, depending on what is in there. So thanks very much. That's a huge help!

Next question... All the photos of tuning plates I've seen have been very manual. Manual to the point that you have to lift up the cooking grates and slide them. Is this something I should spend more time researching? I was thinking about this in terms of making vent ports in the RF plate, similar to an air intake slide at the FB. But that would get all gunked up in a hurry... 
Click to expand...
You're very welcome.  As far as the manual aspect goes, that's the way I've done it in the past, but I don't tend to mess with it much anymore as I have it dialed in as I want it.  You could get a thin piece of metal that has enough strength to it that you could insert it vertically between the grates and move the plates around to fine tune.  Only other thing I can think of is to have a rod that enters a hole on the end farthest from the firebox that has a small lip on the end of it.  You could then push/pull those plates around without having to move the grates.  Horizon shows something similar to this principle with their convection plates:  take a look.

http://www.horizonbbqsmokers.com/backyard-smokers-1/sliding-convection-system-16-smoker
 
Last edited:
loutoo said:
 
gr0uch0, I did some more welding on the RF plate where I thougt it might be leaking after the test Now is about 10 degrees different. Thanks
Click to expand...
You're welcome...if it's everything was tight, I didn't think there was any way that you could have a 50 degree gradient, when that RF plate is supposed to provide the exact opposite effect.  Glad to have been able to help, lou!
 
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