First Build - Patio Hybrid Smoker/Grill Combo

[cp.hooligan]

This is my first post to the forum, but I have been lurking for over year learning and researching to build a replacement for my aging cheap offset smoker. This site has been a great resource!

I am starting to build a combo reverse flow smoker and grill combo hybrid like the Lang Hybrid 36" Smoker Chargrill. I have a 120 gallon propane tank and ready to start building (I think), but I would like some feedback on my design since I have never seen a reverse flow smoker in person and afraid to start cutting/welding without some confidence that this will work.

Here are some pics of the Sketchup design I have been putting together.



Here is the calculator with my dimensions:
Link]Link to BBQ Pit Calculator

The FB was oversized according to the calculator by 170% because I am using part of the tank as the FB and a wanted door on top 14" for convenient access to the fire and I wanted to leave room for an ash pan. So, I reduced the size of the FB using the calculator to determine the actual metrics needed for the intake, exhaust and FB2CC opening estimates. Is this good reasoning or should I just use the actual sizes based on the oversized firebox?

Also, I got a free lab workbench that I would like to use as the frame for the CC. I figure I would need to weld angle iron to support the two legs for additional support. Do you see a problem with this? If not, how should I mount the cook chamber on the frame? The top of the frame sits about 33" off the ground, so the main cooking grate would be around 45". That seems a little high and am worried about the stability of the frame at that height since the legs are 17" apart. Or I thought I could cut down the legs so they cooking grate would be at 36". I modeled this with cardboard in the pics below. Any ideas or concerns using this frame or should I just build one like I laid out in my original design?





Thanks!

[Big T]

You definitely need to use the calculations recommended by the pit calculator or it will lead to performance problems. I think you could modify the base and get the cooker centered on it instead of to one side and it should work fine. I like to keep my bottom rack between 36''-42'' based on the height of the person using the cooker the majority of the time.

[Tom_Heath]

Looks to me like it would work OK. Just DONT push it from the door side, or you may do a back flop. Hate it when that happens. I was helping unload one of Franks cookers and for just a moment I thought it was gonna end up in the lake. Yikes.

Your drawings are looking pretty awesome. For the folks that have never used sketch up just dont appreciate it. I have used it so I can say been there done that.

[Rodcrafter]

I'm having trouble with the dimensions is there 2 FB or is only part of the CC what you are running through the calculator? I agree with Big T stay with the calculator numbers.

[cp.hooligan]

My cook chamber is going to be 24" D x 30"L. If I enter the actual size of FB which I have already cut at 24" D x 17" L, it is oversized by 70%. A 24"D x 12"L FB would still be 20% over and provide the intake, FB2CB opening and exhaust calculations for the heat and air flow sufficient for the CC. I plan on raising the fire grate 8" from the bottom to provide space for the ash tray and bring it closer to the FB2CB opening. It position is based on the volumes required by the calculator and this tool: http://www.mathopenref.com/cylindervolpartial.html
I am concerned that the actual oversized firebox calculations will consume too much fuel.

[Rodcrafter]

I wouldn't raise the FB grate that high for one. I use stick burners only and never needed more than an 2" ash pan for an all day cook. The top of a flame is the hottest part it works for me to allow the heat from the top of the flame to super heat the air in the top of the FB and the draft draws it in and we get a complete combustion burn, which results in a thin blue smoke. You will be surprised how small the fire needs to be once everything gets up to operating temp.
jm2cw

I don't know but I'm missing something on the drawing because it looks to me like the CC is 60" long. Are you using both doors as CC?

[cp.hooligan]

OK, I will lower the fire grate. What about placement of the air intake? Should that be below the grate also or level with the fire grate?

The CC will be split between the smoker 30" and the remaining a grill. I find myself wanting or needing to grill the same day I smoke. I was thinking of adding a diverter to pull hot air from the smoker CC, so that I could use the grill chamber as a warming box or cold smoke in. Is that a bad idea? Maybe this is another reason to use the dimensions with the oversized firebox?

[Tom_Heath]

Intakes below the grate. Fo shore


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[Big T]

[cp.hooligan]

It has been a few weeks and have made some visual progress, see below. I have questions how to proceed...
1) I bought a 3in pipe for the smoke stack, the calculator say it needs to be 51" but says most are between 30-40". To move the smoker out of my garage, I can't go longer than 30in. Will this be long enough?
2) The air intake is partially blocked by fire grate. Should I raise the grate, notch out the portion of the fire grate or other ideas?

Here is the progress:

[Puff]

A great thing I ve done on my 275 trailered smoker was to follow the advice of Gizmo who recommended a stack elbow which can allow the easy removal if the straight 51" pipe. You could also increase the diameter of the stack that would reduce the required length for proper draft.

Look that up if you've not seen one

[Rodcrafter]

I agree with Puff, I did the same thing on my Backyard offset. I did it so a large grill cover would cover it once I stored the stack inside the cc.

[Big T]

If you have room, I would raise the grate up a little bit. You should only need them wide open to get up to temp and then a little opening to maintain temp.

[cp.hooligan]

My firebox is 160% oversized, so I think I can spare an inch and raise the grate.

What do you guys think about dual smoke stacks?

[Rodcrafter]

Dual works fine just make it half as tall

[cp.hooligan]

Next, I need to cut out the center plate that will separate the smoke chamber from the grill and was thinking of putting in an air/smoke diverter that would allow me to cold smoke in the grill chamber. Is this a bad idea? Would I need to size the opening equal to the external intake diverter?

[cp.hooligan]

So, I cut the plate to separate the smoker and grill short by a half inch... I didn't follow the golden rule: measure twice, cut once. All this metal working and welding is new to me and I now have even more appreciation for the smokers produced on this site. This is probably a stupid question, but should I buy another plate or weld the plate back to the scrap and recut? Another plate would cost about $25 for a 2'x2' 3/16 thickness. I am hoping you guys would have some creative ideas or should I just suck it up. Thanks!

[Rodcrafter]

I weld say weld it back together, and re cut it. That is one of the good things about steel, never lost only more work.

jm2cw

[Puff]

Don't feel too bad... I've made these mistakes but when I read so many times that you just weld it and recut, that I finally tried it and it works. Depending on the length, watch for warping by overheating and .... grinding the weld to make it look flat(cosmetically) is a pita...really a pita

[cp.hooligan]

It has been quite a while since I updated progress on my build. Not long after this last post, spring had sprung and then came summer and little progress was made. Sometime in mid-August, I picked up the grinding wheel and welder to get back at this beast of a project. My wife grew tired of the noise, especially the compressor after I decided to sandblast it with a portable blaster from HF before painting because the propane tank was pretty rusted and pitted. That took forever but I got it done and finished spray painting it just as my compressor died. I found a couple of leaks between the FB and CC which I had to fix, but otherwise it runs really well, holds temp, burns nice and clean. I can also control the temp on the grill side well also and the ability to raise the fire grate is convenient. Plus I can easily clean the ash on the grill side by brush it out the air inlet damper into a bucket. I am going to leave it in the garage till the spring and smoke/grill in the drive when the weather is warm enough because I can't bear to see my little baby get covered in snow just yet. This build was a blast! Now onto my next project.....

I really want to say THANKS to all the real professionals on this site. I was able to find answers, general directions or ideas in many other threads to any questions/problems I had during my build.

[Pete Mazz]

[mp4]

Very nice!

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[bluecatfish]

[Big T]

Sweet!!

[Rodcrafter]

Looks great


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