Airburner - HeaterMeter Success!

David Pagels

New member
Longtime lurker here (this may be my first forum post ever). But I got excited and had to post after finally fixing my temperature problems. The answer, in short - MAKE AN AIR BURNER!

I had previously been using a cat dish with a hole drilled in it for a 1 inch pipe and held it to the WSM with 2 toggle bolts. With this configuration, I was unable to get my temps stable even after 2 years of cooks and burning with an empty cook chamber from time to time to try to figure out my PID settings. I never got it to a place I was happy with. Below is the chart of my best shot, running it on Kingsford Blue with a full water pan last year.
beforeairburner.PNG
Drilling a hole in my WSM was the main reason I was hesitant about building an air burner. However, through a bunch of looking around I found this post by Ron Van Iwaarden on this forum talking about how he built and mounted an airburner through one of the air inlets on the charcoal bowl of the WSM. The pictures in the post are now missing, but his instructions were clear and thorough enough that with very little deduction, I was able to construct an air burner that didn't require me to drill through my WSM. Sawing out a couple of small pieces off of the charcoal grate to route the pipe through was the only permanent modification I ended up making in this project. I was ok with this due to how cheap a charcoal grate is compared to the bowl itself.
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Again, credit for this design goes to Ron Van Iwaarden. Please reference his post for more details on this build. I ended up only deviating on 3 things:
  • I added a pipe across the center of the square (8 1/4” long)
  • I shortened the two 1 3/4" long pipes to 1 1/2" so the burner would sit more level in the bowl (the pipes connecting the 90 degree inlet elbow with the 45 degree elbow and the 3/4" tee)
  • I used 3 5/8" lengths of pipe for the shorter runs since 3 1/2" was too short and looked funky when all fit together (8.25" = 2*3.625" - (2.5" - 2*.75") - 2.5" being the width of a 3/4" copper tee)
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For the holes in the airburner - I started off drilling 13 3/16" holes so that there would be some back pressure. After struggling to reach 325 degrees (with fan at 30% max) on my first burn, I decided to add 2 1/8" holes and one more 3/16" hole to get the cross-sectional area of all of the holes up to 15/16th of the area of the pipe. I also didn't initially ream my pipes. I was curious how much of an impact reaming the pipes would have on airflow, so I built a simple barometer using some water, fuel line, copper pipe (to prevent kinks), and some baker's twine. While not very accurate, I marked the fuel line with tape when the blower was off, when the pipe was completely blocked by my hand (the bakers twine) and saw where the water line settled when running the blower at 100% before and after reaming the pipes. The result was the water got ~2/3 of the way to the fully closed pressure before reaming and ~1/3 after. That's a lot of wasted pressure getting past those rough edges!

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After all of that work, the results were fantastic
afterairburner2.PNG
This was on my 18.5" WSM, using Royal Oak lump charcoal, and using my external heat shield wrapped in foil as a heat deflector (no water) and the blower max set to 30%. Overall, this project ended up costing somewhere on the order of $30 for the pipe and fittings. Everything fit together snugly enough that no lead solder was needed. Special thanks again to Ron, and to RalphTrimble - since seeing him preach (and rightfully so!) about the airburner around the forums drove me to search harder for a no-drill airburner solution. Let me know if you have any questions and I'll do my best to answer! Happy smoking!
 
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Bryan Mayland

TVWBB Hall of Fame
Oh wow that looks great! And super-clever using the tubing and water to make a pressure gauge. I built a hot mass airflow sensor and tried to enclose it to get an estimate of airflow across multiple designs but it was very inconsistent to the point the results were unusable. That's a great idea that probably works a whole lot better.
 

ThomasG

New member
David, thanks for taking the time to share this with us. I think that this will be my next project. Could you provide a few more photos showing the other side of the toggle bolt, the part inside the WSM? For some reason, that part of the assembly is not clear to me.
 

David Pagels

New member
Thanks for the kind words and all your work on the Heatermeter, Bryan!

Thomas - This part was probably the most confusing for me to figure out too. Here's a better pic of the inside 90 degree elbow. If you have a 1/8" x 3” toggle bolt, you drill a 1/8" hole in the back of the elbow where the center of the pipe would be if it continued through the bend, then you thread that toggle bolt through so the head is putting pressure on the back of that elbow when screwed in place. After filing down the two sides of the wings of the toggle bolt to be able to grab the shoulders in the 1” x 3/4” reducer (see the 3rd pic in the post), you thread the bolt into the wings and sandwich the WSM and vent in between the reducer and elbow.
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A couple notes - I ended up mangling the spring of the toggle bolt wings when filing them down. That made it finicky to get in place, but is holding well nonetheless. The WSM vent opening is also a bit smaller than the 3/4" pipe, so it constricts airflow a little bit, but still works very well. I also had to cut the 3/4 inch side of the reducer a little shorter so that the threads of the toggle bolt would reach the wings - they just barely did before I did this. A longer toggle bolt would also work.
 

ThomasG

New member
David, thank you very much for the additional info. It looks like I've got all the information I need to get this done. Let's see if I can put this together before smoke day 2020! --T
 

GSpinelli

New member
I have been putting off the airburner project for a long time, but this post inspired me to complete it. I have to say that it makes all the difference on my WSM 18.5. I have always struggled with the cooling affect of the blower causing dips on stoking, and required careful setting of the fire, and only ever got "OK" performance. This is a graph of my first run with the AirBurner. Definitely by best ever on the WSM (and it was windy). Note it would have been perfect, except I had to add some charcoal (I skimped) around noon.
 

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David Pagels

New member
GSpinelli That's fantastic! I also suspected that cat bowl attachment I was using before the airburner was causing some sort of cooling effect for me too, but there wasn't much info about that around the forums. The most info I found on it suggested trying to make some sort of deflector inside the WSM to direct the air down. That might have worked, but sounded too finicky for me and you can't argue with these airburner results!
 

RalphTrimble

TVWBB Diamond Member
I'm glad you guys are having success with the air burner. I am quite happy with the original unit I built for my bullet smoker, even after I built the RotoDamper I never replaced the air burner on the bullet. It has served me well, I get nice flat graph's so why mess with perfection! The only negative would be that I think I burn a bit more charcoal with the air burner than I would with the RotoDamper, but the food comes out really great so the air burner lives on.
One thing I love about the air burner is I can light the pit with a small wad of paper placed over one of the jets, no other "fuel" needed, it just fires up like magic!
 

David Pagels

New member
@TTrappen I haven't had airflow problems due to ash getting in the holes while smoking. Afterwards, I shake out the leftover charcoal over the airburner/charcoal bowl, then remove the airburner and tap it on its side, then on the bottom to get all ash to the side of the inlet and then shake the ashes towards the inlet to get any ashes out for the next cook.
 

JW Evans

New member
Went with stainless pipe... Still lots to dial in, but definitely like the idea of an "airburner" over a cat dish!

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RalphTrimble

TVWBB Diamond Member
Went with stainless pipe... Still lots to dial in, but definitely like the idea of an "airburner" over a cat dish!

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You're missing the "burner"? The air-burner concept was based on the small holes forcing air to concentrate into jet like streams that stoke the fire efficiently (like tiny fireplace bellows) with minimum air flow. I like your pipe implementation, and agree it beats the hell out of the dog bowl, but without the "burner" part you're not going to get the air burner effect. I'd suggest you give the burner a try...
 

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