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rwc565
09-12-2008, 12:55 PM
Iam currently in the process of drawing up plans for a smoker I'm having built. I want to built a reverse flow. I want the cooking chamber to be 48" X 24". My question is..the length of the chamber is 48", how long should the channel from the firebox be? I'm thinking 42" does that seem right?

Fatback Joe
09-12-2008, 01:24 PM
I have heard (I am no builder) that you want the gap at the end of the plate to be the same distance as the distance from the plate to the bottom of the smoker.........did that make sense?

Have your flow plate 42 inches if the plate is 6 inches of the bottom of the smoke chamber for your example.

If you were only going 4 inches off the bottom of the chamber than go with 44, etc.

Made sense to me when I heard it........thought of it as just a continuous pipe, not getting too big or shrinking too slow the air flow.

rwc565
09-12-2008, 02:26 PM
[quote=Fatback Joe;14930]I have heard (I am no builder) that you want the gap at the end of the plate to be the same distance as the distance from the plate to the bottom of the smoker.........did that make sense?

Yes it makes sense to me. Unless someone else can dispute this and tell me a better way, this is the way I will go. Thanks for the imput.

rwc565
09-12-2008, 03:55 PM
I guess my next question should be, how high off of the bottom should my reverse flow plate be?

Fatback Joe
09-13-2008, 11:46 AM
How big are you planning on the opening from the firebox to the cook chamber?

Maybe one of the Lang users will chime in with the distance on a Lang.

SmokyOkie
09-13-2008, 11:56 AM
What is the benefit of reverse flow other than it looks cool?

nmayeux
09-13-2008, 01:22 PM
No hot spot, even cooking temps from side to side, reduced threat of grease fire, you can fill the pan with beer and steam brats, and having the stack on the same side as the fire box sometimes freaks people out!

Here are some pics of mine, but I don't have the measurements. Maybe it will give you an idea of the proportions. Also the pic of the smoke chamber is tilted, but if you look closely, you will see that the pan drains towards the dam where it goes to a 2" drain. The pics aren't real clear, and the smoker is a little dirty...

http://i38.photobucket.com/albums/e129/Nauti-Que/LangInnards1.jpg

http://i38.photobucket.com/albums/e129/Nauti-Que/LangInnards2.jpg

http://i38.photobucket.com/albums/e129/Nauti-Que/LangInnards3.jpg

http://i38.photobucket.com/albums/e129/Nauti-Que/LangInnards4.jpg

SmokyOkie
09-13-2008, 03:03 PM
No hot spot, even cooking temps from side to side, reduced threat of grease fire, you can fill the pan with beer and steam brats, and having the stack on the same side as the fire box sometimes freaks people out!

I don't have any of those problems with Lucille, and have never had a grease fire, even with as much as 300# of meat on at once. but I will admit the stack config is cool.

What pan are you talking about?

Here are some pics of mine, but I don't have the measurements. Maybe it will give you an idea of the proportions. Also the pic of the smoke chamber is tilted, but if you look closely, you will see that the pan drains towards the dam where it goes to a 2" drain. The pics aren't real clear, and the smoker is a little dirty.


I'm glad to hear that. That means I can trust youcuz I never trust a man with a clean smoker


Lang 60? I've cooked on one of those.

nmayeux
09-13-2008, 04:02 PM
I guess by "pan," I am really talking about the baffle. I call it a pan, because you can grease her up and use it like a griddle for pancakes with the cooking grates removed. You can adjust the temp range from end to end by raising or lowering the trailer tongue. The problem with a lot of traditional offsets (not Lucille!), is that built up grease can run into the firebox, or that embers from a hot fire can ignite built up grease in the chamber. Because the Lang baffle can "hold water," and forces grease to the drain, it is much harder to ignite built up grease. However, I have seen a reverse flow with so much grease that it over flowed the dam and ran back into the firebox with predictable results...

The way that I look at it is that the reverse flow design is just a part of the progressive evolution of the traditional offset. Its just that someone replaced tuning plates with a solid pan, and moved the stack. The stick burning offset design is my favorite style of smoker, and the reverse flow is my favorite version of the offset. I still have a special place in my heart for Lucille, but Marie is my lady! What Marie doesn't know, won't hurt her...;)

As for cleanliness, I do suffer from a foil fetish...

SmokyOkie
09-13-2008, 06:10 PM
Better foil than a clean smoker! I like the idea of grilling too!

nmayeux
09-13-2008, 06:37 PM
One thing I forgot to mention is that I think reverse flow works better on smaller smokers. Once you get to a certain size, the benefits of reverse flow diminish rapidly. If you think about the hot spot alone, in a small smoker like a Chargriller, this could take up to a third of your cooking space when smoking. On one of those monster Klose rigs, you might lose 1/100th... Just a thought though!

JamesB
09-13-2008, 06:42 PM
No hot spot, even cooking temps from side to side

Do you not have a hot spot on the firebox side? On my 8' x 30" reverse flow, I have two hot spots, well hotter than the rest of the chamber. First, and hottest is the first foot or so down by the firebox. The plate there catches the radiant heat from the firebox... The other is at the opposite end where the plate ends and the hot air/gasses rise. The rest of the cook chamber is very consistant.

I can also change the heat characteristics of the pit by raising or lowering the tongue...

Just really curious if you have a hot spot down by the firebox.

nmayeux
09-13-2008, 06:52 PM
James,

It really depends on the size of the fire and the angle of the smoker. I sometimes will keep the tongue down and build up the fire to create a hotter spot which is where I will cook my beans. However, if I keep the tongue up, I can use the entire cooking grate. My Lang is small enough that I guess the radiant heat from the fire box roughly equals the hot exhaust into the chamber.

rwc565
09-15-2008, 07:45 AM
I guess my next question should be, how high off of the bottom should my reverse flow plate be?


How big are you planning on the opening from the firebox to the cook chamber?

Maybe one of the Lang users will chime in with the distance on a Lang.After reading Fatbacks question, I was able to answer my own question. If I make the firebox opening 6"top to bottom, then my reverse flow channel would have to be 6" off of the bottom as well.

rwc565
09-15-2008, 08:25 AM
What is the benefit of reverse flow other than it looks cool?
My thought on a reverse flow is, more even temps through out. And also it would work like a convection oven, warm air circulating on top and bottom.

After looking at BaLoKo's post on his new smoker, I may rethink my plans and put an upright on the end of the horizontal instead of making it a reserve flow. I'll have a few questions to ask before I make my decision. BTW thanks to everyone who has responded so far, it is helpful.

PigCicles
09-15-2008, 09:11 AM
Why not make it a reverse flow WITH a warmer? Look at the Lang's with the warmer.

SmokyOkie
09-15-2008, 09:37 AM
It's an awful lot of time, effort and money to build a vertical oven that's nothing more than a warmer. If you're gonna build a vertical oven too, you ought to make it one that you can cook in as well as warm.

SmokyOkie
09-15-2008, 09:49 AM
My thought on a reverse flow is, more even temps through out. And also it would work like a convection oven, warm air circulating on top and bottom.

Any stickburner is a convection oven. Reversing the flow of the hot gases doesn't chnge that. Convection is merely the circulation lf hot air, and hot gases moving from the firebox to the stack are exactly that. If you want more turbulence and thus more even temps, just put a baffle in the path of the hot air stream and cause it to vortex or "eddy".


Think of convection like this:

If you sit in a hot tub of water, it stings at first. After you sit there for a minute or two, it no longer stings because the water that is in contact with your skin has assumed a temperature halfway between the temp of your skin and the hotter tub water temp. If you move, it starts to sting again because you've disturbed the "cooler zone".

If you add a jacuzzi jet to that equation, it never stops stinging because the "cooler zone" never forms.

Now, if you apply the same concept to meat in an oven, you can see that exactly the same would happen to the meat, and the result is that meat cooks quicker. This is not the same as cooking at higher temps, it's only a matter of cooking with a true temperature as opposed to one that gradually gets hotter as the meat cooks.

As applied to BBQ, the result is better bark and juicier meat cooked in less time.

This is one of the reasons that I'm liking my Backwoods more and more all the time. We took a trial spin with the water pan filled with sand yesterday and produced world class spares in 2 1/2 hours. If we can repeat it on Saturday, I have no doubt that we will be in the top 5.

rwc565
09-15-2008, 10:31 AM
Any stickburner is a convection oven. Reversing the flow of the hot gases doesn't chnge that. Convection is merely the circulation lf hot air, and hot gases moving from the firebox to the stack are exactly that. If you want more turbulence and thus more even temps, just put a baffle in the path of the hot air stream and cause it to vortex or "eddy"..
Your exactly right, I wasnt looking at it like that. That is why your the go to guy on this forum! You have all of the answers. thanks.

SmokyOkie
09-15-2008, 12:42 PM
Your exactly right, I wasnt looking at it like that. That is why your the go to guy on this forum! You have all of the answers. thanks.


And some of the time I'm even right!:wow::blushing:

nmayeux
09-15-2008, 06:50 PM
Like SO said, the reverse flow doesn't aid in convection. What it does is help even the temps out. The pan acts like a heat sink, just the same way that SO's pan of sand does. It also forces hot air to the oposite side of the cook chamber that when coupled with the radiant heat from the fire end creates an even temp over the entire cooking surface.

As for the warmer, Ben Lang has been cutting holes in the top of his fireboxes and installing a damper to make the box a better cooker. But to be honest, I really like the simplicity of my little Lang, and I would want a large charcoal grill attached to the front of the trailer for steaks and burgers more that I would want the warmer. However, one of these days I will own an 84 deluxe with chargriller! Best of both worlds!!!

SmokyOkie
09-15-2008, 09:39 PM
Reverse flow is only good if it's well engineered. The Lang's seem to be well engineered.

Whatever you build, make sure you know what you're building.

Noah, I may know where a Lang 60" with and upright and a chargrill could be had.

It's the only Lang I ever cooked on, and if I recall, the "warmer" had a temp diverter to send heat to the warmer for cooking.

I just looked at their site and didn't see one like it, so theirs must've been a custom.

jerry516planes
12-23-2008, 05:57 AM
There are 5 factors in any smoker design.

1. Volume of smoke chamber.
2. Volume of Fire Box.(Rule of thumb is about 1/3 of smoke chamber volume)
3. Size of the Draft opening. (from outside into firebox)
4. Size of opening from Fire Box to Smoke chamber
5. Size of Chimney and How tall.

All are interrelated. The normal mistake is to build the fire box too big and to trap heat in the fire box thus wasting wood. The outlet from the firebox should be the highest point in the fire box.

Pit Ratios are Alien to most of us. Try this link http://www.thesmokering.com/forum/viewtopic.php?t=20871

If I can be of further help please do not hesitate to ask!

Happy Holidays

Jake
12-23-2008, 02:13 PM
I'm glad to hear that. That means I can trust youcuz I never trust a man with a clean smoker

hey wait a minute, thats just not right.


Lang 60? I've cooked on one of those.


As for cleanliness, I do suffer from a foil fetish...[/quote]
good for you, i scrape and foil.

and thanks for the link, but i gotta say the Q is better:msn-wink: the link is going to come in handy as i go to build soon:thumbs up: also a uds is going to be made.:thumbs up:

SmokyOkie
12-23-2008, 04:20 PM
There are 5 factors in any smoker design.

1. Volume of smoke chamber.
2. Volume of Fire Box.(Rule of thumb is about 1/3 of smoke chamber volume)
3. Size of the Draft opening. (from outside into firebox)
4. Size of opening from Fire Box to Smoke chamber
5. Size of Chimney and How tall.

All are interrelated. The normal mistake is to build the fire box too big and to trap heat in the fire box thus wasting wood. The outlet from the firebox should be the highest point in the fire box.

Pit Ratios are Alien to most of us. Try this link http://www.thesmokering.com/forum/viewtopic.php?t=20871

If I can be of further help please do not hesitate to ask!

Happy Holidays

Don't forget stack location. I'm big on placing the stack outlet in the middle of the end of the unit as opposed to being on top.

I also cooked on a bottom feed unit for years and it worked great. In fact, I'd still be using it except it finally died of canceer. The smoker doctor said it was from a lifetime of smoking.:msn-wink:

Chargrilled
12-23-2008, 07:00 PM
There are 5 factors in any smoker design.

1. Volume of smoke chamber.
2. Volume of Fire Box.(Rule of thumb is about 1/3 of smoke chamber volume)
3. Size of the Draft opening. (from outside into firebox)
4. Size of opening from Fire Box to Smoke chamber
5. Size of Chimney and How tall.

All are interrelated. The normal mistake is to build the fire box too big and to trap heat in the fire box thus wasting wood. The outlet from the firebox should be the highest point in the fire box.

Pit Ratios are Alien to most of us. Try this link http://www.thesmokering.com/forum/viewtopic.php?t=20871

If I can be of further help please do not hesitate to ask!

Happy Holidays

OK, so if what your sayin is true I havta install a angled plate in my firebox to the opening as there is a couple inches from firebox to chamber.

And in agreement with the SO, I went outta my way to get a smoker with a exhaust in the middle of the cookin surface.

I am not a reverse flow man but I do sorta see the benneys. I love my offset and how I build my fire is where I get even cook temps side to side. That and its damped and I use tuning plates. :roflmaoha0:

jerry516planes
12-24-2008, 02:23 AM
Don't forget stack location. I'm big on placing the stack outlet in the middle of the end of the unit as opposed to being on top.

I also cooked on a bottom feed unit for years and it worked great. In fact, I'd still be using it except it finally died of canceer. The smoker doctor said it was from a lifetime of smoking.:msn-wink:

I totally agree with you on the stack loaction! Well said :twocents: I also believe the stack should extend down to just below or even with the cooking grate.

SmokyOkie
12-24-2008, 10:23 AM
I totally agree with you on the stack loaction! Well said :twocents: I also believe the stack should extend down to just below or even with the cooking grate.

Agreed. The middle is where the grate should be as well.

When I mentioned a bottom feed unit, I failed to mention the internal firebox. I'm a big fan of internal fireboxes as opposed to offsets. With an internal firebox, all the heat stays in the unit. In an offset, there is an emormous amount of heat loss through the box itself. It you can get ahold of a large enough iece of pipe, go for the internal firebox.
right Short One?

jerry516planes
12-24-2008, 12:30 PM
Agreed. The middle is where the grate should be as well.

When I mentioned a bottom feed unit, I failed to mention the internal firebox. I'm a big fan of internal fireboxes as opposed to offsets. With an internal firebox, all the heat stays in the unit. In an offset, there is an emormous amount of heat loss through the box itself. It you can get ahold of a large enough iece of pipe, go for the internal firebox.
right Short One?

:roflmaoha0::roflmaoha0:

Agreed. By looking at what you own that is clearly appearant!

In my current project I included 1/2 of the fire in the cooking chamber. I left 1/2 out side for warming hot water. It would be a great location for an oven/warmer/vertical smoker. That has been the long range plan from the beginning. I am borrowing that idea from Mr. Lang.

My next project is going to based on a piece of 30" 0.375 wall gas pipe. This piece is 72" long. Jet Deck has convienced me insulate it and the fire box. I have been toying with the Idea of a gravity feed fire box, mounted below and in the middle to take advantage of the heat rising and you make an excellent point above!!! Just basic thermo dynamics and not rocket science.

Without a doubt the backwoods win a large number of cook offs! As I learn more about smoking I have decided that I will have a backwoods sooner or later. I just have to finish all my other projects. Right now I just want something finished so I can get back to cooking.:wings:


Merry Christmas to all!!

Chargrilled
12-24-2008, 01:20 PM
right Short One?

And gorgeous she is, :wow: Love at first sight:wings:

PigCicles
12-24-2008, 03:27 PM
And gorgeous she is, :wow: Love at first sight:wings:

She's MINE Trav - back off in your own jack yard buster :misbehaving: :censored2: