Help on a smoker build

[Denarii Welding]

Hey all, been a while since I have asked anything on here. Looking for some help with my first smoker build. Im using a 120 gallon scrap propane tank, does anyone know how to calculate the stack? Firebox size and opening to cook chamber? Do you recommend reverse flow? Or should I just do a offset? Why? Does this change the size of anything? Any help would be much appreciated. Last time i posted i asked something similar. I saw how to calculate the opening but that was for offset and im not sure if that changes anything or not. Finally getting to the build now. Have the tank ready amd cut the door out so hoping to have it done soon.

 

[JckDanls 07]

Yep.. everything you need to know right here... I built mine to the exact numbers the calculator put out and works like a charm... My build is in my signature line below...

This is the calculator...

Reverse Flow Smoker... How to calculate build tutorial...

> Reverse Flow Smoker... How to calculate build tutorial... By DaveOmak This is a tutorial and you will need a calculator and paper to note desired dimensions... This tutorial has been proven to make an excellent operating Reverse Flow smoker... Here's to "Alien BBQ" and the folks that first...

www.smokingmeatforums.com

 

[seenred]

Hey all, been a while since I have asked anything on here. Looking for some help with my first smoker build. Im using a 120 gallon scrap propane tank, does anyone know how to calculate the stack? Firebox size and opening to cook chamber? Do you recommend reverse flow? Or should I just do a offset? Why? Does this change the size of anything? Any help would be much appreciated. Last time i posted i asked something similar. I saw how to calculate the opening but that was for offset and im not sure if that changes anything or not. Finally getting to the build now. Have the tank ready amd cut the door out so hoping to have it done soon.

Afternoon Friend!

I haven't built a traditional offset, but have built a reverse flow. My understanding is, the dimensions for each is about the same. Here's a handy online calculator that I've used a time or two:

Feldon's BBQ Pit Builder Calculator

Red

 

[Denarii Welding]

Hey thanks. I will use that and see what it gives me. Much appreciated.

 

[Denarii Welding]

Yep.. everything you need to know right here... I built mine to the exact numbers the calculator put out and works like a charm... My build is in my signature line below...

This is the calculator...

Reverse Flow Smoker... How to calculate build tutorial...

> Reverse Flow Smoker... How to calculate build tutorial... By DaveOmak This is a tutorial and you will need a calculator and paper to note desired dimensions... This tutorial has been proven to make an excellent operating Reverse Flow smoker... Here's to "Alien BBQ" and the folks that first...

www.smokingmeatforums.com

Thanks. Will also take a look at this.

 

[Grillman365]

in for the pics

 

[JBW450]

I never used the calculators (didn't know they existed) when I build my reverse flow.

A mate of mine built one years ago and started with the baffle at 1/3 of the smoke chamber and he said it wasn't ideal. He then modified it to be 1/4 and it works great now.

I took that on board and did the same. I also did a test burn with the baffle just sitting in position before welding it in just to confirm good draw etc.

 

[JBW450]

That’s really useful advice, especially doing a test burn before welding the baffle permanently. Being able to make adjustments at that stage seems like a smart way to avoid problems later. Thanks for sharing your experience—it definitely gives me a few things to consider for my own build.

FWIW, I just realised that I wrote that around the wrong way.

Should be "A mate of mine built one years ago and started with the baffle at 1/4 of the smoke chamber and he said it wasn't ideal. He then modified it to be 1/3 and it works great now."

The original baffle I cut and trial fitted was similar (around 1/4). Without even welding it in I made a bigger baffle and then did a test burn.

Wasn't sure what I was looking for burn wise but figured if the wood caught alight easily and burnt fast and with open dampers then it was probably about right.

Depensing on your design you can further change airflow by changing the size of the mesh/grate that your fire will be burning on. My smoker for example has the firebox damper underneath the grate so as the coals burn down they fall out the damper holes. I trialed smaller mesh grates which greatly affected how well the fire breathed.

Ultimately, I settled on some stainless steel mesh with approximately 15mm square holes...

 

[JckDanls 07]

The 15 mm mesh detail is really helpful too.

Also, the V shaped fire baskets is where it's at... Keeps all your coals more concentrated and therefore lites the split quicker.. Which actually helps conserve fuel as well...

 

[JBW450]

Also, the V shaped fire baskets is where it's at... Keeps all your coals more concentrated and therefore lites the split quicker.. Which actually helps conserve fuel as well...

Great tip, now I need to make a conical fire basket to try in my round firebox

 

[JckDanls 07]

started with the baffle at 1/3 of the smoke chambe

Yes... 33% volume size... But its also been said that a little bigger doesn't hurt... Now that's on the firebox/baffle size... Your opening from firebox/baffle to the chamber should only be 33% (or 1/3)
Also, I'm assuming what you are calling a baffle is also what's called the firebox ??

I'm also a believer in your coal grate only being 1/3rd (33%) of the way up from the bottom of the firebox.. ...

 

[JBW450]

Yes... 33% volume size... But its also been said that a little bigger doesn't hurt... Now that's on the firebox/baffle size... Your opening from firebox/baffle to the chamber should only be 33% (or 1/3)
Also, I'm assuming what you are calling a baffle is also what's called the firebox ??

I'm also a believer in your coal grate only being 1/3rd (33%) of the way up from the bottom of the firebox.. ...

Baffle meaning the floor/divider between the smoke chamber/cooking area and the firebox (on a reverse flow offset).

Obviously in this case if the baffle/floor is too low the fire may not draw very well due to the restriction.

 

[in. pred]

one thing i learned from an offset is it eats fuel at stupid rate. and unless your cooking a bunch of meat its just not practical. imo the fire box of an offset should be highly insulated. that bare metal box dissipates a huge % of the output. either incorporate it into the cook chamber or insulate it. thats my view on offsets. my guess is, you would get an 80% reduction in fuel use! that is my observations from cooking with both offset and fire in chamber designs.