Insulated RF build

Discussion about Reverse Flow Smokers
Post Reply
aldaeron
beginner
beginner
Posts: 6
Joined: July 22nd, 2016, 10:12 am

Insulated RF build

Post by aldaeron » November 2nd, 2018, 1:08 am

Howdy all – occasional lurker here who is finally getting his act together to take a design from paper to the back yard. Recently bought a Hobart 190 and a sheet metal shear/press/roller combo and have decided to try to motivate myself to build something so that I can make Thanksgiving turkey for the family in a new smoker.


I am a mechanical engineer by background and have the tendency to way over think things and play around in CAD a lot. I was hoping to do a little more searching on the forums to see if some of these questions have been answered before, but since I am looking at 3 weeks to finalize my design, fab and test a new smoker I am hoping some of you can help me reach my goal by pointing me in the right direction.


I live in Denver, Colorado and for the past few years have been getting by with a Camp Chef pellet smoker that I have gasketed the crap out of (thank you BBQ Smoker Supply!) and after borrowing a Weber Smoky Mountain for a big cook I want to get back to using charcoal and wood to cook with instead of pellets. I am all for iterating and tweaking in the future, but for now I am looking for something fairly basic that I can use to smoke food for my family and the occasional pre-Broncos get together.


It is super, duper, duper dry here and can get cold-ish in the winters (20-30 F). For better or worse, I have decided to make these design choices, though I am open to suggestions:

Insulated firebox and chamber
o Main thought here is to maintain chamber temp in the dead of winter nights and conserve fuel
o The little shear I have can’t cut very thick steel sheet and I don’t have anything to move heavy material around
o Plenty of off-the-shelf smokers seem to be able to get away with 16 gauge steel. Two layers of sheet steel with some 8 PCF insulation sandwiched inside seems pretty good to me
o I don’t have a ton of cash to dedicate to the build and can’t afford some of the monster plates I have seen in some of the very cool designs featured here

Rectangular chamber not cylindrical
o I don’t know anyone with a spare propane cylinder
o Even if I did, I don’t have the space or handling equipment for one of those beautiful offsets
o 90 degree cuts are easy and quick

Start simple, but leave room to add on later
o I am an engineer after all and LOVE to overcomplicate things. And tinker.
o One idea I would like to figure out someday is a PID controller that feeds the firebox with charcoal or lump wood like a pellet smoker (I admit the “set-it-and-forget-it” part of pellet smokers is super convenient)


I took a lot of clever little design choices from many of your posts, tips and pictures, particularly the beautiful Mack (awesome work Frank!). Below is the concept I have in CAD so far. Explained:
1x1 square tube (grey) about 66” tall to top (I am 6’2” and dislike bending down). Skinned with 16 gauge sheet steel (light blue) with 1” thick 8 PCF ceramic insulation between the two layers. Single Door (green) with same insulated sandwiched metal and lined with gasket where it closes. Insulated Firebox (red) with internal water pan (not shown) and chimney to chamber (yellow). Exhaust via chimney on far side (brown). Sliding removable racks of some sort (purple, will have more than 1). Handy shelf in the front (grey – may add more or make it fold someday).



I figure the one thing I won’t want to change is the chamber size so I went what I think is pretty big for me. At 36x24x24 I have lots of room for airflow and can fit in at least 4 briskets (I can barely squeeze 2 in my Camp Chef now) or a million racks of ribs (give or take a few)

Chamber volume as shown is 36x24x24 = 20736 in^3
Pit calc gives me:
Firebox volume of 6912 in ^3 (Firebox shown is 24x24x12 = 6912 in^3)
Chimney size of 4x4x22 long (chimney shown is 4x4x24)
Firebox Air Intake area of 20.8 in^2
Throat of 55.3 in^2 (The yellow tube between firebox is 9x6 = 54 in^2)


Hopefully you’re still reading this mound of text because here are the questions I have:


1) I mostly cook for my family (Myself, wife and 3 kids). Will having such a large chamber with only a few racks of ribs or a single brisket still work well (other than using more fuel to heat it)? I have never used a big smoker.
2) Will a firebox below design like I have work ok? Most designs I have seen have the firebox hanging off the chamber somehow. I was planning to make the area of the tube connecting firebox and chamber equal to the throat from PitCalc.
3) The firebox size seems huge to me, but I have faith in PitCalc. Do I need much more than a simple box with a raised grate? Do I count the area under the grate in the Firebox volume? How high should the grate be off the floor of the firebox? Should I make a vee shaped grate so all the coals tend to slide toward each other as they burn? Any clever ideas to make cleaning out ash are appreciated!
4) For the firebox shape I was thinking short and fat like I have drawn, but am really clueless about what to do here.
5) Where should I put my water pan? Was thinking in the firebox near the outlet with a little door on top to fill from.
6) The reverse flow seems like the most popular design. Should I have a plate on the bottom that the hot air passes under? This seems like overkill, but could double as a grease collector.
7) Is it better to put the chimney outlet on the top, middle or bottom of the chamber wall on the far side? Or maybe make multiple smaller chimneys to control airflow in the chamber better? Does it really matter that much?
8) What kind of baffle plates (if any) should I put in the chamber where the hot air enters?
9) Should the area of the chamber include the volume on the side where the air enters or just the part where meat goes (the purple rack shown is 36” wide)?
10) What kind of grease handling system would you recommend? Was thinking of slightly angling the plate at the bottom of the chamber into a well-sealed collecting cup that I can remove (so outside air can’t get in). Looks like ball valves are popular, but I was also considering a decent diameter piece of threaded pipe to make a cup out of. I also see some arguments for a leaving the grease on a flat plate to allow grease to sizzle and add flavor back in.
11) How close vertically should I place my racks? Was thinking I could fit in 4 racks spaced 4-6 inches apart. Unless someone has a clever concept for a supporting rail that can slide somehow.
12) For racks it looks like an angle iron frame with expanded steel is popular. I have always like the round bar type grates. Any reason for one over the other?
13) A single 36” wide door instead of two 18” wide doors seems simpler to build and less places to seal with gaskets. Not sure if I should make it swing up or sideways either. Any feedback on this is appreciated.


Ok that’s all I can think of for now.

Once I get building I will post pictures.

Thanks for reading!

-matto-
You do not have the required permissions to view the files attached to this post.



User avatar
Pete Mazz
Moderator
Moderator
Posts: 2722
Joined: February 16th, 2013, 8:19 am
Title: Meathead
Location: Bucks County, PA

Re: Insulated RF build

Post by Pete Mazz » November 2nd, 2018, 3:54 am

Why not just make a vertical smoker? A little more compact and you'd have more room for racks. Also more efficient than channeling the heat/smoke thru a riser. Make it 26x26x66 (or whatever high).

http://www.smokerbuilder.com/forums/dow ... =19697&t=1


If it's tourist season, how come I can't shoot 'em?

Don't speak the language? Try this: Smoker Terminology

Try my SmokerBuilder Calculators

aldaeron
beginner
beginner
Posts: 6
Joined: July 22nd, 2016, 10:12 am

Re: Insulated RF build

Post by aldaeron » November 2nd, 2018, 8:03 am

Hey Pete,

You just turned my head on its side! Great idea! I searched around and found some decent info on cabinets from the forums.

Couple of questions

Is a 24x24 rack rally big enough for a full packer brisket? I was thinking 28x24 would be the minimum for some of those 20 pound monsters I see at Costco.

I saw some discussion of a RF cabinet where the smoke enters at the top and is drawn through to the bottom - does the extra tube and drawing reverse offer something I am missing?

Would you put some baffle plates or a water pan above the throat to spread the heat out?

Is there any benefit to two chimneys (one on left and right) vs one in the center? Thought is to draw air around in certain way by how the exit is placed. This post says that dual chimneys are not that important but doesn't say why.

In this post there are a lot of similar questions to what I have. A couple comment stick out. Is a water pan really needed in low humidity places? I took a ribs class at the nearby BBQ shop and they were talking about how hard it is to retain moisture here so I figured I should try to add some in. There is also a comment from @mp4 that the reverse flow makes a better smoke flavor than a vertical cabinet. I bet both are better than my current pellet smoker, but I was curous if others think this too and if it is because the smoke flows across the whole piece of meat instead of vertically around it and therefore penetrates better. I would think this would make sense for ribs, especially if they are bone side down - seems like the smoke would not curl around the bones and contact the meat on the top very well.

You all are awesome! Thanks!!!



User avatar
Dirtytires
Expert
Expert
Posts: 1535
Joined: November 24th, 2015, 12:36 am
Title: It ain't broke...yet
BBQ Comp Team Name: Dont compete...cook for events once in a while
Location: Phoenix, Az

Re: Insulated RF build

Post by Dirtytires » November 2nd, 2018, 9:58 am

Obviously I don’t know what your talents are or how your work area is set up. I have a dedicated workshop and all the big tools to go in it to make building more convenient. With that said, it still took me 6 months to build a rf smoker. I have several hundred hours in build time and many nights roaming the computer to order special hardware. I’m not saying it can’t be done but I have seen too many people set themselves up for failure with an unrealistic time line. Take your time, do it right and wait till next year for the turkey.

Water pans are over-rated. Some use them but I smoke in the desert in Phoenix and got rid of mine years ago. Too much hassle and I can’t tell that it helped any. Some do use them for a heat-sink and not moisture but I think there are better alternatives for that too.

I’ll wait to tackle any of your other questions as it seems you are still deciding what to build.



Chromeski
Big Time SmokerBuilder
Big Time SmokerBuilder
Posts: 255
Joined: July 20th, 2018, 6:59 pm

Re: Insulated RF build

Post by Chromeski » November 2nd, 2018, 12:25 pm

I agree with the dirtytires, this seems like an ambitious build for such a short time frame and untested design. I have no doubt it's possible, but assuming you have a day job and obviously a family this may fast become overwhelming.i say you cook this years Turkey in an uds and next year the new vertical or offset that you build.
I am all for new designs and creative build projects focus on what you want as far as size, fuel and burn time and work from there. One other thing that I seen is in my area it seems 2" insulation is more readily available than 1 or 1.5 inch. Whatever you decide remember to post pics



aldaeron
beginner
beginner
Posts: 6
Joined: July 22nd, 2016, 10:12 am

Re: Insulated RF build

Post by aldaeron » November 2nd, 2018, 3:00 pm

dirtytires & Chromeski,

I appreciate your concerns about the timeline. I am often overly ambitious with timelines and I do not think completing the project by Thansgiving is likely. Honestly I have 2-3 years of scribbles, sketches, ideas, CAD models and I am frustrated with myself and need a swift kick in the butt to start. I am perferctly fine using my old pellet grill to make turkey in a few weeks. I really appreciate your feedback so I don't get in over my head. Family always comes first.

I am at the point where I am fine with building something that may not work great and would be ok walking away from it completely. Or doing a lot of re-cutting, grinding and re-welding. I feel like if I can order material and throw the first bead I will be more than 50% there (mentally). I just need to get out of my headspace and fabricate something with a good chance of success. I really do appreciate all the resources that folks have contributed here and apologize that I didn't do a better job reading past posts.
Dirtytires wrote:
November 2nd, 2018, 9:58 am
Obviously I don’t know what your talents are or how your work area is set up. I have a dedicated workshop and all the big tools to go in it to make building more convenient. With that said, it still took me 6 months to build a rf smoker. I have several hundred hours in build time and many nights roaming the computer to order special hardware. I’m not saying it can’t be done but I have seen too many people set themselves up for failure with an unrealistic time line. Take your time, do it right and wait till next year for the turkey.
Can you elaborate on what took you so long that you didn't expect when you started? Sites like https://www.bbqsmokersupply.com/ have a lot of the more difficult stuff to find from what I can tell (handles, gaskets, chimney parts, etc). I also have a buddy with 3-4 CNC Mills at his house who can be bribed into helping or fabricating parts.

I am a decent MIG welder and used to belong to a local makerspace that had a CNC plasma (amongst other toys that I know how to use). I am not a professional fabrcicator, but I think I know enough to be successful and safe. I have designed hundreds of parts for manufacture over my career and am usually pretty good about thinking my way through all steps fof building something. As you may have gathered, I don't have much experience with larger smokers and tend to get a little over analytical.

Dirtytires wrote:
November 2nd, 2018, 9:58 am
Water pans are over-rated. Some use them but I smoke in the desert in Phoenix and got rid of mine years ago. Too much hassle and I can’t tell that it helped any. Some do use them for a heat-sink and not moisture but I think there are better alternatives for that too.
Appreciate the feedback - this seems to be everyone's experience on this forum. Most of the folks I know who make BBQ are in humid climates and I can never tell if some of my cooks are a little dry because of climate, flare-ups or not wrapping as much when I cook. I really want to get more smoky flavor into my meat, but I make pretty decent stuff in my pellet grill (photos attached)

Chromeski wrote:
November 2nd, 2018, 12:25 pm
One other thing that I seen is in my area it seems 2" insulation is more readily available than 1 or 1.5 inch.
This is the insulation I found: https://www.amazon.com/dp/B01BIDUED0


Dirtytires wrote:
November 2nd, 2018, 9:58 am
I’ll wait to tackle any of your other questions as it seems you are still deciding what to build.
After thinking about Pete's feedback, the Vertical Chamber seems like a perfect fit for what I want. I am at work and can't sketch it up right now, but I will make some new CAD this evening to better illustrate. After re-reading my questions and thinking about it more, here is my parsed down question list:

1) Can I use pit calc for a vertical cabinet the same as for an RF?

2) I think something around 28x24x36 will be a good CC size. Will having such a large chamber with only a few racks of ribs or a single brisket still work well (other than using more fuel to heat it)?

3) I saw some discussion of a RF cabinet where the smoke enters the CC at the top and is drawn through to the bottom to exhaust - is this worth the extra effort?

4) What kind of baffle plates should I put in the chamber where the hot air enters? I have this Marianski bros book with a bunch of baffle concepts (https://www.amazon.com/dp/B004S2CRYS) that I plan to lean on, but appreciate advice.

5) What kind of grease handling system would you recommend for a vertical cabinet?

6) How close vertically should I place my racks? Was thinking I could fit in 4 racks spaced 4-6 inches apart. Unless someone has a clever concept for a supporting rail that can slide somehow.

7) For racks it looks like an angle iron frame with expanded steel is popular. I have always like the round bar type grates. Any reason for one over the other?


Appreciate your pateince and feedback. This forum is a really great resource and if you're ever in Denver, first beer on me!

-matto-



User avatar
Dirtytires
Expert
Expert
Posts: 1535
Joined: November 24th, 2015, 12:36 am
Title: It ain't broke...yet
BBQ Comp Team Name: Dont compete...cook for events once in a while
Location: Phoenix, Az

Re: Insulated RF build

Post by Dirtytires » November 2nd, 2018, 4:34 pm

Actually, my build took just as long as it took. I didn't try to rush it, didn't cut corners and didn't ignore my family/work obligations. At the time, i worked full time and only got 20 hours or so a week to work on it...mostly after my family went to bed. My advantage tho was that i have dedicated work shop so didn't have to clean things up every night to pull the cars in the garage.

Obviously you put a steel order in for the bulk of your build but always need another piece of something so i made several trips to the steel yard. I ran put of gas on a Friday....guess what....nobody open till Monday. Solved that problem tho and bought a second tank. Same issue with wire...thought i had a spare roll but didn't. I probably put 3 orders in thru Grainger for odd things like a 2 inch ball valve, plunger pins for my shelf, wheels, threaded rod and heim joints for my steering setup and so forth. Every setback adds a few days till you can get back to it.

And life happens. The family goes on vacation, gotta work an extra shift, neighbor needs help on a Saturday, school activities or my wife has a business trip. It all adds up into days of no productivity. The more you use a deadline to push you the more you cut corners and your build suffers.

I am concerned that you spent 2-3 years planning your ideal build yet still dont know what build will fit your needs. Planning your build is the single most important part of the project and greatly determines if your build will be an instant success or a constant cause of aggravation. We all want you to have years of trouble free cooking cause that is where the fun is.



Chromeski
Big Time SmokerBuilder
Big Time SmokerBuilder
Posts: 255
Joined: July 20th, 2018, 6:59 pm

Re: Insulated RF build

Post by Chromeski » November 3rd, 2018, 1:46 am

Sounds like you have a good handle on this, just gotta decide what your building.
The calculator is designed for offsets, I do not think there is one for vertical cabinet builds.
The expanded metal grates are popular because they work and are practical. The most important thing is whatever grate you use needs lots of holes for smoke and air to pass.
Put the guides close together to allow lots of grates, make them removable so you can remove for large pieces and stack them all in for smaller cuts.



User avatar
Pete Mazz
Moderator
Moderator
Posts: 2722
Joined: February 16th, 2013, 8:19 am
Title: Meathead
Location: Bucks County, PA

Re: Insulated RF build

Post by Pete Mazz » November 3rd, 2018, 4:17 am

After thinking about Pete's feedback, the Vertical Chamber seems like a perfect fit for what I want. I am at work and can't sketch it up right now, but I will make some new CAD this evening to better illustrate. After re-reading my questions and thinking about it more, here is my parsed down question list:

1) Can I use pit calc for a vertical cabinet the same as for an RF?

2) I think something around 28x24x36 will be a good CC size. Will having such a large chamber with only a few racks of ribs or a single brisket still work well (other than using more fuel to heat it)?

3) I saw some discussion of a RF cabinet where the smoke enters the CC at the top and is drawn through to the bottom to exhaust - is this worth the extra effort?

4) What kind of baffle plates should I put in the chamber where the hot air enters? I have this Marianski bros book with a bunch of baffle concepts (https://www.amazon.com/dp/B004S2CRYS) that I plan to lean on, but appreciate advice.

5) What kind of grease handling system would you recommend for a vertical cabinet?

6) How close vertically should I place my racks? Was thinking I could fit in 4 racks spaced 4-6 inches apart. Unless someone has a clever concept for a supporting rail that can slide somehow.

7) For racks it looks like an angle iron frame with expanded steel is popular. I have always like the round bar type grates. Any reason for one over the other?
1) No. The PitCalc is for offsets. All you need is to make the FB large enough to handle charcoal or splits. Make the basket tapered toward the bottom or, if strictly charcoal with some wood chunks, or a maze style.

2) My racks are 24 x 18 and fit a full packer, 2 chickens, 2 pork butts or 3 racks ribs.

3) IMO, RF verticals are a waste of time and money. Verticals are very efficient and do not suffer from hot spots per say.

4) I use a water pan. I've tried lava rock and sand as a heat sink/diffuser but have gone back to water. Maintains heat much more evenly thru the cook, catches all the drippings and is easy to clean (in my instance I designed my smoker around the size of aluminum sheet pans)
First-Smoke.jpg
5) If you make a diffuser/drip pan, make it with a 2" lip and a drain. Leave a couple inches clearance around it for heat/smoke and use a drip rail a few inches above it to direct drippings into the pan. It also gets the heat/smoke to redirect off the sides and back to the center of the CC.

6) 4" is a good spacing. Some use 3" and add extra rails.

7) Expanded steel is much easier, just make sure it's "flattened" version 3/4 x 9
You do not have the required permissions to view the files attached to this post.


If it's tourist season, how come I can't shoot 'em?

Don't speak the language? Try this: Smoker Terminology

Try my SmokerBuilder Calculators

aldaeron
beginner
beginner
Posts: 6
Joined: July 22nd, 2016, 10:12 am

Re: Insulated RF build

Post by aldaeron » November 6th, 2018, 1:25 am

Pete,

Appreciate the answers! I have decided to cut my racks down to 24x24 max (I may go down to 24x18). I have been getting better at honing my search terms and have been focusing on what questions I need to finalize my design.

I think the build that is most similar to what I am looking at is this one by MattJ: viewtopic.php?f=17&t=6594 I already PMed him to see if he would give more feedback now that he has been off and running a few more months since his last post.

I also like the design of viewtopic.php?f=17&t=6794 but that one isn't built yet.

Most of the insulated verticals from recent times seem to be some variant of the GF design from Frank and company. The biggest thing I am curious about with that design is the offset firebox and U shaped baffle design. It seems like Frank is a busy fellow - does anyone know if he does consulting? Once I get my design all CADed up I wouldn't mind paying him to review it and give feedback over the phone or something like that.

My next round of questions (I will try to get sketches or CAD going if these descriptions don't make sense):

1) If the calculators for firebox size aren't appropriate for an insulated vertical - what does everyone recommend? It seems like insulated verticals do not need a lot of heat once they're going, but many of the fireboxes look huge (though some are using the Minion method to minimize fire tending). The size of the throat on the SmokerPlans GF looks very small and is only fed by a tiny ball valve (handful of square inches)

2) What kind of diffuser/baffle is recommended? Perforated steel sheets (https://www.metalsdepot.com/steel-produ ... ated-sheet)? Many designs seem to have a 3/16 to 1/4 plate with a few cutouts on the sides to allow heat out (with optional water pan in the center) and a chimney located dead center on the top. This does seem to be the way to go, but I am not sure how to size the open area (throat area?) of the diffuser plate.

3) I see a few options for fireboxes:
a) Simple rectangular basket (which seems to be used with minion method burning down from the top),
b) Maze type (or maze basket as discussed here: viewtopic.php?f=129&t=6833). This seems risky if the fire jumps and difficulties getting air to all parts of the maze as it burns.
c) Offset firebox / Gravity feed. Not sure if it is a requirement to have the firebox offset from the CC to make a gravity feed work. Seems like you might be able to make an airtight chute with an angle at the end and put the gravity feed firebox below the CC. This is the thing I am most curious about on this design - is there an advantage to an offset firebox and a vertical cabinet? Can a gravity feed be made with a firebox underneath the CC? Seems like a firebox under the CC is cheaper and easier to do and the minion method is almost as easy to do as a GF.
(Aside: This design is a super neat idea for an offset firebox being used for grilling: viewtopic.php?f=17&t=5934)

4) For an insulated vertical it seems like keeping the heat down low enough is the difficult part. How should the intake be sized? Seems like a single pinwheel or ball valve provides more than enough air. This did get me wondering about combustion temperature. If there is so little air and a super hot starting fire, is there any concern that the wood or charcoal will smoulder or get sooty and acrid? Would it be better to be able to remove some of the insulation on the CC time to allow more air flow while maintaining the same CC temps?

5) Safety time. I have a garage overhang that I usually hide under while brisket and ribs turn into meat candy. Vertical designs look like they can be 4 to 6 feet high and the ceiling is at 10 feet on my overhang. I could add a chimney offset to throw the smoke clear of the roof edge (it's only a few feet of an offset). Or maybe a diffusing fan on the chimney? Or adding a heat resistant plate to the ceiling of the overhang? I guess I could wheel the smoker in and out of the overhang, but it's not my first choice.

Thanks again for the help!

-matto-



User avatar
Pete Mazz
Moderator
Moderator
Posts: 2722
Joined: February 16th, 2013, 8:19 am
Title: Meathead
Location: Bucks County, PA

Re: Insulated RF build

Post by Pete Mazz » November 7th, 2018, 4:50 am

1) If the calculators for firebox size aren't appropriate for an insulated vertical - what does everyone recommend? It seems like insulated verticals do not need a lot of heat once they're going, but many of the fireboxes look huge (though some are using the Minion method to minimize fire tending). The size of the throat on the SmokerPlans GF looks very small and is only fed by a tiny ball valve (handful of square inches)
You have to decide if you're going to use charcoal or sticks. You'll need more height with sticks. 12" would be plenty for charcoal.
2) What kind of diffuser/baffle is recommended? Perforated steel sheets (https://www.metalsdepot.com/steel-produ ... ated-sheet)? Many designs seem to have a 3/16 to 1/4 plate with a few cutouts on the sides to allow heat out (with optional water pan in the center) and a chimney located dead center on the top. This does seem to be the way to go, but I am not sure how to size the open area (throat area?) of the diffuser plate.
The diffuser can be a solid sheet of 1/4" steel, just leave a couple inches around the perimeter.
3) I see a few options for fireboxes:
a) Simple rectangular basket (which seems to be used with minion method burning down from the top),
b) Maze type (or maze basket as discussed here: viewtopic.php?f=129&t=6833). This seems risky if the fire jumps and difficulties getting air to all parts of the maze as it burns.
c) Offset firebox / Gravity feed. Not sure if it is a requirement to have the firebox offset from the CC to make a gravity feed work. Seems like you might be able to make an airtight chute with an angle at the end and put the gravity feed firebox below the CC. This is the thing I am most curious about on this design - is there an advantage to an offset firebox and a vertical cabinet? Can a gravity feed be made with a firebox underneath the CC? Seems like a firebox under the CC is cheaper and easier to do and the minion method is almost as easy to do as a GF.
Minion method works by controlling intakes. Temps can run away if opening the CC too often or not paying attention.
Maze baskets enable you to load more charcoal for extended cooks. You can light just one end or both for different temps. The design of the maze will prevent all the charcoal from catching.
If you want a GF I highly recommend purchasing the plans. They are quite a different animal and I wouldn't want to redesign the wheel and have it not perform.
4) For an insulated vertical it seems like keeping the heat down low enough is the difficult part. How should the intake be sized? Seems like a single pinwheel or ball valve provides more than enough air. This did get me wondering about combustion temperature. If there is so little air and a super hot starting fire, is there any concern that the wood or charcoal will smoulder or get sooty and acrid? Would it be better to be able to remove some of the insulation on the CC time to allow more air flow while maintaining the same CC temps?
Intakes are one of those things on a smoker that's best to have too many. Changing wind direction may stoke the fire so the ability to open one side or the other helps. You could also design the intake so that a blower unit could be used. Makes it set and forget. Quite a few folks use UDS's and they basically function the same way. Airflow is controlled by the intakes and exhaust. Adding dampers gives you the most flexibility.
5) Safety time. I have a garage overhang that I usually hide under while brisket and ribs turn into meat candy. Vertical designs look like they can be 4 to 6 feet high and the ceiling is at 10 feet on my overhang. I could add a chimney offset to throw the smoke clear of the roof edge (it's only a few feet of an offset). Or maybe a diffusing fan on the chimney? Or adding a heat resistant plate to the ceiling of the overhang? I guess I could wheel the smoker in and out of the overhang, but it's not my first choice.
Verticals by nature are themselves chimneys. All you really need is an exhaust at or near the top of the CC. I use a small 12" fan a few feet away to redirect the smoke if it's not going where I want.


If it's tourist season, how come I can't shoot 'em?

Don't speak the language? Try this: Smoker Terminology

Try my SmokerBuilder Calculators

aldaeron
beginner
beginner
Posts: 6
Joined: July 22nd, 2016, 10:12 am

Re: Insulated RF build

Post by aldaeron » November 10th, 2018, 1:36 am

Pete,

Many thanks again! I am working toward a final design now and costing things out. Pretty sure I am going to make the exterior of the chamber 48" to make it a little cheaper when ordering sheet metal. I have my CAD 80% of the way there and have a few last detailed questions before I post the design.

1) If I want to burn sticks instead of charcoal with chunks - how tall should FB be? 16 inches? What's the reasoning for the extra height? Seems like you can fit 3-4 logs in a 12" firebox

2) Figured I might want to do a removable ash tray to make it easier to clean. Is it worth making a 2" deep box with a grate on top that I can set my fire basket on?

3) I was planning to use 1" blanket insulation and am trying to decide between 14 and 16 gauge. I plan to use 11 gauge for lining the inside of the firebox. I will use a little more tube or flat bar to prevent sagging, but prefer the thinner (and cheaper) material. Am I getting a little too cheap here or will 16 gauge work?

4) Is the Nibco full port bronze ball valve still a good choice? viewtopic.php?f=149&t=6435&p=96681

5) If I use a Cyber q style fan like viewtopic.php?f=56&t=5446#p79347 can I get away with one inlet?

3) For a 26x22 rack size using an angle iron frame with 3/4 x 9 expanded metal do I need a to add a piece of flat bar in the center to prevent sagging? Have seen a bunch of racks that sag in various photos.

Thanks!

-matto-
You do not have the required permissions to view the files attached to this post.



Chromeski
Big Time SmokerBuilder
Big Time SmokerBuilder
Posts: 255
Joined: July 20th, 2018, 6:59 pm

Re: Insulated RF build

Post by Chromeski » November 10th, 2018, 2:11 am

The reason for a taller firebox is because the sticks don't burn well without a taller ceiling. Charcoal will burn almost anywhere if there is oxygen.
16 ga should be fine for the outside skin on an insulated firebox.
I think that size grate will do fine without the extra support
I think a single intake will work fine with a controller just need a large enough fan, but why limit yourself add a couple vents with a way to shut them down.
I think a removable ash pan is a great idea
I'm sure those ball valves are great cuz czar said so.
I would consider thicker insulation although not required



aldaeron
beginner
beginner
Posts: 6
Joined: July 22nd, 2016, 10:12 am

Re: Insulated RF build

Post by aldaeron » November 10th, 2018, 1:04 pm

I think I will weld in two or three 2" pipes and just cap two for now. Prefer to limit buying extra ball valves til I have to spend the money. Will probably put them all on one side for now.

Is 16 ga ok for the cook chamber inside wall?

Is 2" insulation noticeably better? My little pellet grill has no insulation and does pretty well, figured 1" would be plenty.

For the lower door I was debating between a standard door that swings left to right. I was curious about maybe putting the hinge on the bottom like an oven door. Or maybe doing a fire "drawer" that slides out like those freezers on newer fridges. Anyone ever try any of these?



User avatar
Dirtytires
Expert
Expert
Posts: 1535
Joined: November 24th, 2015, 12:36 am
Title: It ain't broke...yet
BBQ Comp Team Name: Dont compete...cook for events once in a while
Location: Phoenix, Az

Re: Insulated RF build

Post by Dirtytires » November 10th, 2018, 1:42 pm

Most Everybody here uses 2 inch upinsulation but they use rolux. I found a ceramic insulation that is 1 inch thick that actually has a better r-value than the 2 inch stuff and it works great for me. Al always, it depends what you are expecting in the final project. (I wanted safety...it drops the external skin of my firebox TO around 200-275 degrees.)

My grates are 40 by 24 and don’t have a support. Minimal sag...



User avatar
Pete Mazz
Moderator
Moderator
Posts: 2722
Joined: February 16th, 2013, 8:19 am
Title: Meathead
Location: Bucks County, PA

Re: Insulated RF build

Post by Pete Mazz » November 11th, 2018, 5:25 am

:yth:


If it's tourist season, how come I can't shoot 'em?

Don't speak the language? Try this: Smoker Terminology

Try my SmokerBuilder Calculators

Post Reply

Return to “Reverse Flow Smokers”