horizontal rf smoker 1st build

[swampyankee]

I am building a horizontal rf smoker. Will be using a chuck of 30x54.5 in pipe which is 38504.25 cubic inch.
The firebox will be 24x28.375in pipe which is 12836.17 cubic inches. The firebox will be placed perpendicular to the cooking chamber.
The vent pipe will be 6x22.71in which is 641.81 cubic inches. The fire box air inlet will be 3-4in holes? The firebox to cook chamber opening 6x18in?
Was wondering what you guys think. Do I have to hit the cubic inch numbers on the money for the air inlet and firebox to chamber or can I go a little bigger?
Does the vent have to come off the top of the cooking chamber or would it be better to come out the center end of pipe then 90 up?
Door opening on the cooking chamber was thinking twelve o'clock to 1in below three o'clock. Go bigger or smaller?  How much room should I leave at the end of reverse flow plate to the end of pipe?
The grill should be even with the bottom of the door correct?

thanks

 

[rob989_69]

I am building a horizontal rf smoker. Will be using a chuck of 30x54.5 in pipe which is 38504.25 cubic inch.
The firebox will be 24x28.375in pipe which is 12836.17 cubic inches. The firebox will be placed perpendicular to the cooking chamber.
The vent pipe will be 6x22.71in which is 641.81 cubic inches. The fire box air inlet will be 3-4in holes? The firebox to cook chamber opening 6x18in?
Was wondering what you guys think. Do I have to hit the cubic inch numbers on the money for the air inlet and firebox to chamber or can I go a little bigger?
Does the vent have to come off the top of the cooking chamber or would it be better to come out the center end of pipe then 90 up?
Door opening on the cooking chamber was thinking twelve o'clock to 1in below three o'clock. Go bigger or smaller?  How much room should I leave at the end of reverse flow plate to the end of pipe?
The grill should be even with the bottom of the door correct?

thanks

I'll give you my very unprofessional advice and then hopefully someone with a whole lot more experience will. be along shortly. You do not have to be exact with the numbers. They are a very good guide to follow basically allowing you to get the best draw from the firebox all the way through the cook chamber and out the stack.

The firebox is, for me anyway, where I try and get as close as possible to the 1/3rd recommended size. Too small and you may not be able to heat the cook chamber high enough. Too big and you'll heat it too much. As far as the door openings. I'd say 12 - 3 is about average. You could do 1 - 3 if you're doing bigger doors and counter weight them. I know when I asked the same question to Solaryellow in his build thread he said he did his to the 12 oclock position and if he could do it again would go to 1 oclock. As far as the grate levels with regards to door openings, you are correct. If your grates are NOT pull out grates then I'd go level with the opening at the bottom or just below. If you are doing pull out grates then obviously you want them just above the opening.

Regarding size, go as big as you can to get what you want. Basically, if I had my way, and someone elses money, I'd have a lang 60, which is roughly the size you're talking about. But since I'm using my money, and materials are scarce around here, I went with a 60 gallon air tank. Not as big as I'd like but it will serve me now and probably for a good while till I can afford something larger. All that to say. If you have room for something bigger and think you may have a use for it later, go bigger. If you think that will cover your needs then it's the perfect size.

Hopefully I helped some. And not to overstep my bounds but make sure you put your location in your profile. 

Good luck!

 

[solaryellow]

I am building a horizontal rf smoker. Will be using a chuck of 30x54.5 in pipe which is 38504.25 cubic inch.
The firebox will be 24x28.375in pipe which is 12836.17 cubic inches. The firebox will be placed perpendicular to the cooking chamber.
The vent pipe will be 6x22.71in which is 641.81 cubic inches. The fire box air inlet will be 3-4in holes? The firebox to cook chamber opening 6x18in?
Was wondering what you guys think. Do I have to hit the cubic inch numbers on the money for the air inlet and firebox to chamber or can I go a little bigger?
Does the vent have to come off the top of the cooking chamber or would it be better to come out the center end of pipe then 90 up?
Door opening on the cooking chamber was thinking twelve o'clock to 1in below three o'clock. Go bigger or smaller?  How much room should I leave at the end of reverse flow plate to the end of pipe?
The grill should be even with the bottom of the door correct?

thanks

I am going to echo a lot of what Rob said.

I have a question about the 6x18 number. Since you pipe has a 24" diameter, are you planning on mounting it a little high and then cut a rectangle out of it? If so, I would recommend cutting out an 8" ellipse starting at the top of the 24" pipe for your firebox opening. That will put you right at the recommended firebox opening size. If you mount the firebox high and then cut out a rectangle, you will trap heat above your firebox opening.

I would try to stay close to the numbers but they don't have to be perfect.

You can mount the chimney however you want. You won't gain much by putting the chimney lower. The chimney volume is the important part in order to maintain a good draft.

As for your doors, I am going to reference the drawing above. Assuming the doors are on the LEFT of this drawing, I would make the top at 1 o'clock and the bottom 4" or more above the RF plate so about 9 o'clock at a rough guess.

You want the same amount of area or a little bit more at the end of your RF plate as you do for your firebox opening.

Unless you want to try and reach way in the back, I would put them at the bottom of the door and make sure they can slide in and out.

 

[bruno994]

With a pit 30" deep, I would go with pull out grates for sure.  Mine is 24" and as long as I did not have a top grate, reaching into the back would not be a problem, but with a tank that size, make the most out of your space and put in a top rack, so pull outs are a great way to go.  You can always pull out the top grate and cook something taller (turkeys, hogs, etc.).

Can't wait to see this build.

 

[swampyankee]

    Hey guys. I have been really busy, had a baby girl ect. just got back to working on the smoker. I changed the fire box from round to square . Took my pieces of pipe cut lengthwise and then used press brake and roller to flatten out to make my square fire box and end caps for cook chamber.
    Saved some money not having to buy stainless flat plate. My firebox is 24x24x24 =13824. Bigger then recommend but not by much. The firebox to cooker opening is 103.82. Should be a half moon shape size of 19x7.5 = 105.96. Does this sound right? now my reverse flow plate needs to be 1 1/2 times the 7.5in of the opening? 11.25? and that's what I need for space and the end of plate correct? going to try and post up some pics this week .
 

 

[daveomak]

Swampyankee, evening..... Since you are changing to a rect, firebox....  I took the liberty of drawing you out something.... 

I changed your firebox to 24x27x20....  That is 102%... and the 27" will mate up to the RF plate which is 1.5 times the FB to CC opening in area for reduced friction of the air flow...  The numbers I used are in the link below and the circle calc. is there also....

Any questions we are all here...  solaryellow has built a great smoker and knows the ins and outs and what needs to be done to make it work for you... and improvements that should be considered when building.....    

Swampyankee.jpg

• daveomak
• Mar 18, 2013

http://feldoncentral.com/bbqcalcula....93&fi=0,0,4,38.88,3.10&fc=11.49,16.25,103.68

http://www.1728.org/circsect.htm

 

[swampyankee]

they only problem is i already made and welded the 24x24x24 fire box.
 

 

[bruno994]

You should be fine.  As long as your numbers show that you are close, it will work.  The pit calculator is a great reference and helps get you in the ballpark.  I'm sure Dave will be here to offer up some more of his wisdom soon.  Now let's start seeing some pics!

 

[daveomak]

24" wide will be fine.....  Do the same cut-out for the FB/CC opening...  You can make the cut -out even with the top of the firebox or lower it 1"....  I would lower it 1" from the top of the FB in the event you want a plate welded in there to keep the top of the FB cooler...  A heat deflection plate that could extend into the cook chamber.....  It shouldn't be needed if you install 2 air intakes to the firebox.... 1 below the fire grate and one above .... the one above moves heat from the firebox to the cook chamber...for more even heat distribution... uses less fuel and better temp control...

Below is an example of SQWIB'S deflector plate install...  The bigger red plate is inside the firebox and a dead air space is good insulation....  the 2nd red plate is under the first section of the RF plate to reduce the heat there....  Like i said previously, it may not be necessary with good heat / air management with adjustment of the 2 air inlets......  

If you need a better drawing of your setup I will gladly do that...    Dave

                                                        

Squibs deflector plate.jpg

• daveomak
• Mar 19, 2013

 

[swampyankee]

took some pics for you guys today.

smoker 1.jpg

• swampyankee
• Mar 20, 2013

smoker2.jpg

• swampyankee
• Mar 20, 2013

smoker3.jpg

• swampyankee
• Mar 20, 2013

smoker4.jpg

• swampyankee
• Mar 20, 2013

smoker5.jpg

• swampyankee
• Mar 20, 2013