Small 100lbs propane tank build

tomasz · May 17, 2013

Hi all,

I posted this in the UDS category but it has evolved a little. I still need plenty advice as the build is still in the early stages of development.

It was going to be a vertical smoker with a small footprint for easy storage with the fire in a basket at the bottom. It has since been suggested on another forum that I mount it horizontally and just keep the fire at one end. I then had the thought of building a divider to help even out the heat at the food end. The thing I like about the horizontal design is that I can use it as a big grill or maybe make a rotisserie mod if I fancy it. I did this quick visualisation and would like some feedback. I think the chimney is too large for a start! Was thinking of a ball valve for the intake. What size do you think I need? Do you think the divider will make any difference?

Thanks in advance!

Here are the pics and the visualisation:

kc5tpy · May 18, 2013

Hello from the midlands (please view my profile ). I have built a couple BBQ's in my time. This can be a complex question. BIG difference between grilling and smoking. What do you plan to do with this pit? As I know British BBQ you plan on a big party pit with lots of burgers, sausages and chicken legs. With a rotisserie attachment maybe a leg of lamb? Nothing meant by those statements but the answer makes a big difference to your build. What you read elsewhere about fire one end is called an offset smoker. You can see one on here or go to E-Bay U.K. and search for large charcoal BBQ. My avatar is of one. If you plan on long slow cooks of several hours then that is what I would build. Remember your plan will always have a hot spot at the fire end. If you just plan the big party pit as mentioned above, I'd leave it open and spread your coals evenly across the bottom. Couple of suggestions, mount your pit at a slight angle with the stack end downhill and drill a hole at the bottom to drain fat away. Add a second grill under the cooking grill to put your coals on so air can get underneath. Bottom grill should be made from concrete reinforcement bar or other such type, a thin grill will just sag from the heat. Let me know if I can help further. Keep Smokin!

tomasz · May 18, 2013

Thanks for the input!
I mainly want to build this for low and slow cooking. I'm thinking racks of ribs and pulled pork etc! But it is nice to have the option for direct grilling, which is why this setup will hopefully work well for me. Yes I do plan on the classic british 'BBQ' party but I will probably smoke overnight or from early in the morning with this setup and do the direct grilling on another grill.

kc5tpy · May 18, 2013

Been really thinkin about this build..I see where you wanna go. Just remember that a super-duper all-purpose do everything pit will always fall short slightly in each different use. I have 4 different pits depending on use. The plate will help to hold heat and radiate temp. You will always have one HOT end and one cooler end. Place your long and slow toward the stack end. With your idea you must open the whole pit to attend the fire losing heat and smoke, as opposed to an offset smoker build. Not rainin on your parade, just food for thought. Now for your questions. Stack: 3" ( 75-80 mm ) with a damper should do it. I'd say 18" ( 450mm ) long. I wouldn't use a valve for air intake. British gardens tend to be small and sometimes you have trouble getting a breeze, I have even had to put a fan in front of my smoker for air flow. I searched a long time but found you 2 intake options. I prefer the slide intake as it can offer more airflow in the hard times but I think either will work. Just remember you must have a fire grate/grill to get air under your fire. Here is the link, scroll down and you will see the intakes. Hope this helps. Let me know if I can help further.

http://www.smokingmeatforums.com/t/135437/quick-and-easy-pie-vent

Keep Smokin!

tomasz · May 19, 2013

Wow, great comments. Thanks so much! Can't wait to get back to work on it. The intakes look good, I will have a think about that.

I wonder if it is too late to make a separate small door for the fire. I know it will still let heat and smoke out but it might help a bit.

I will re-post with an update soon although I have to work away this week.

kc5tpy · May 21, 2013

The fire door will help. Also just looked at your drawing again. Your design is difficult as you are trying for a hy-bred. That's what keeps drawing my thoughts. I think in this case I would leave the plate out. Get it to the test burn stage fire it up and see how it performs. I worry the plate at the bottom or top will change air flow in a undesirable way. The plate could then be tack welded into place, another test run and compare results. If the plate helps, weld it in solid. Easier to add at this stage rather than cut out a solid weld after painting and you shouldn't have to change your whole design, plate in or out. Remember to seal everything you can, leaks make control harder. Just food for thought. I'll be watching. Keep Smokin!

sidpost · Jun 1, 2013

How's your build going? I'm contemplating a lot of my own options as well.

An offset smoker is what I really want and seems to match your intended cooking. The offset firebox will keep the heat, smoke, and moisture in while allowing you to tend the fire. If you put a plate in on the hot end you can even the temperatures out with some "tuning".

You could also go all out with a reverse flow heat baffle to heat up fast and retain an even cooking temperature across the entire cooking surface. Think of it like a little tube from the firebox to the opposite end of the cooking chamber with the exhaust stack near the firebox end.

For a direct charcoal grill, the bottom of a "55 gallon" oil drum could be easily adapted. Then your "garden parties" would have the best of both worlds, nice slow smoked meats and direct grilled options.

tomasz · Jun 3, 2013

Hi all,

Sorry for the silence. I have been a little busy but I have managed to weld the other hinge on so now I have a door.
Tomorrow I think I will go to an exhaust place and have them bend me a 3" piece of pipe for my stack.

Reverse flow would be an interesting option but I think I will keep it simple to begin with and think about more complicated designs later on. I will certainly leave the plate out or at least loose to begin with and see how the test runs go. I also cut in the side door.

Next job is to fit the stack and weld overlapping strips for the door. I will prob tack these on and then seal them with some kind of fire cement or fire proof sealant.

Will post more pics soon!

tomasz · Jun 6, 2013

Quick update:
I have cut the foot off as that is where I will put the small fire door. I bought the angle piece from an exhaust place and partly welded it in place. I can then slot a piece of pipe in when I want to use it, which means I can store it vertically.

kc5tpy · Jun 6, 2013

Ya can't yell WHOA! in tha middle of a horse race. Hello. Have been wondering how you are getting on. What I meant is you posted a drawing and asked for advice, then you changed the actual build. You changed the position of the stack from the top to center end. That changes the dynamics of how the smoker will perform. I have built a few smokers and you will find that small changes CAN make a BIG difference. Not a mistake ( in fact might have been exactly what was needed ) but requires rethinking about the plate. The plate at the bottom now might make a big difference in a good way. I still think though you are on the right track now. Test burn a couple times with and without the plate. It's looking good. You will be having some good eats soon. Keep going and keep us updated. Keep Smokin!

Danny

roller · Jun 6, 2013

I think it looks great and just the right size...

kc5tpy · Jun 6, 2013

BTW. I have looked at your build several times as you know, and I wish I had thought to tell you to put the stack there.

I think that might just be what your build needed.

Keep at it and keep us updated. Good luck.

Danny

tomasz · Jun 7, 2013

I wish I had seen this thread before I started http://www.smokingmeatforums.com/t/124744/small-rf-build-using-a-100-pound-propane-tank

I probably would have copied it!

Anyway I am pushed for time as it is so keeping it simple for my first build is probably no bad thing.

Thanks again for the input. I moved the stack after a suggestion from someone on a UK forum after posting the design. No more drastic revisions planned at the moment! I will hopefully get a step closer to testing this weekend but the sun is shining so drinks with friends in the park may hinder progress slightly!

kc5tpy · Jun 7, 2013

You did read that build was a reverse flow?? That wasn't where you were going. So long as you got it sorted now. We all know the British are WELL known for their smoker designs. So you must be well on your way. Good luck.

tomasz · Jun 7, 2013

Yes and I like the idea of making a reverse flow but that is for another time! I am going to get some work done on this one in the morning.

Having looked at some calculations I think that the stack is probably almost long enough as it is. What do you think?

daveomak · Jun 10, 2013

Tomas, morning...... That looks like a good design... sort of a Jambo down flow.... they work well and I think you will be pleasantly surprised just how well it works... The plate by the firebox is needed to give an indirect heat/smoke for the smoker, and the lowered exhaust location is necessary for uniform distribution of heat/smoke.... several designs like yours have been built and talked about on here..... Keep going and I'm looking forward to seeing some great Q.... Be sure the door has a good seal or establishing a good air/heat/smoke flow will be impossible... Air tight is the key...

Having looked at some calculations I think that the stack is probably almost long enough as it is. What do you think?

How tall, above the Cook Chamber, is the stack ?? Probably should be about 24-30"..... for good draft..... Looks like an extension can be easily added if necessary...

Dave

tomasz · Jun 12, 2013

Hi all,

Thanks for your help Dave. I am really pleased that you have seen success with similar designs in the past. Do you have any advice for the plate? Should I cut holes in it or just leave a gap at the top as in my visualisation. I'm not sure how the smoke would act if I did that.

I mounted the pipe that way round to easily slot in a stack extension so that is no problem. I have just ordered some fire rope and will be working on the doors tonight.

Last night I cut the smaller fire door.

I have optimistically ordered a brisket of beef for this weekend and a leave in digital meat probe I had ordered arrived in the post. I have a dial probe which I will have mounted on the door.

Here are the latest pictures:

tomasz · Jun 13, 2013

My cousin dropped round a 12lbs beef brisket this evening! Better get a move on as I plan on cooking It on Sunday and I will need to give the cylinder a good burn out before then. It still smells of the smelly of gas (or whatever they put in the gas so you can smell it)

daveomak · Jun 13, 2013

Not much left to do.... divider next to the firebox...... cooking grates..... burn it out and smear the inside with pork fat and season it.... season the meat grates also..... kind of like seasoning a cast iron skillet.... cook the brisket and take plenty of pictures..... I am interested in how well this "down flow" type smoker cooks... I'm thinking of building one....

Dave

tomasz · Jun 17, 2013

Final update:

Well I got it finished and have smoked a brisket with reasonable success.

I ran out of time and welding gas so some of my already sloppy work got worse. I ended up doing a very basic intake after getting fed up using the hole cutting bit. I used a stiff hinge and just cut a square with a stalk and door knob. It actually worked quite well though and I was able to control the temp fairly easily after getting used to it. It needs a very small fire to keep it at smoking temp but this means you have to tend to it regularly. I had a separate fire going because some of the wood I was using was a bit green and smokey.

I didn't give myself enough time to do the brisket. It only got ten hours when it probably needed closer to 15 given the weight.

Burn out:

After burn out:

Intake:

Relocating to scenic spot!:

Smokin':

Part way:

Brisket:

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