Austin XL - looking for advice on a homemade mod to help with temp differences

brewersfan73

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I'm looking for a little advice from folks that know a thing or two about the airflow in the Austin XL cooker. I think this would also apply to anyone that has one of the larger PB pellet grills (1000, 1100, 1150, & 1600) with this "large diffuser plate" that sits on top of and around the burn pot. It doesn't look like the small cookers have this same design.

PXL_20220726_000822730.jpg

At some point, I'm sure I can share the full report, but in an effort to keep this brief (which this probably won't be), here's what I discovered so far. I put the 4 Inkbird temp probes on the cooking grate like this, trying to get a feel for the temp differences across the grate from left to right:

PXL_20220725_222018388.jpg

And before people just say "buy the flame diffuser and/or heat deflector mods", please bear with me. I'm hoping to find a different solution that might work.

When I kept the PB diffuser plate installed, the right side of the grill was hotter than the left side by about 30-50 degrees. I also noticed that the Inkbird probe on the left side, closest to the Pit Boss temp probe, was typically 20-40 degrees hotter than the PB probe (so if the grill controller was set at 225, the left side of the cooking surface was 260, and the right side was over 300). I talked with PB customer service, and in addition to sending me a new temp probe, they suggested I try running the same test without the large diffuser plate.

So I went ahead and did the test, and low and behold, the hot spot switched sides. Or more accurately, the hot spot turned into a cool spot. First thing I noticed is the Inkbird probe on the left side practically matched the PB temp probe (I did not install the replacement that they sent me). So if I set the grill at 225, the left side of the grill was around 225. Great! But now the right side of the grill is 30-50 degrees COOLER than the left side.

So that got me thinking - can I just add some vent holes to this diffuser plate and find a happy medium?

My questions to you PB owners are:
1. Does this make sense? Is there any reason not to try this, knowing that once I drill some holes in this plate, I can't go back?
2. If it makes sense, where do you suggest I try drilling first (see picture below)? I'm not really sure where to start. I've thought about it a lot, and I keep going around in circles. I'm trying to take into account how the heat rises and circulates, how to make sure that the PB temp probe is reading the correct temperature, how to make sure I'm not creating a new issue, etc. If I had a couple extra of these diffuser plates, I would just starting drilling and see what happens, but I don't.

2022-07-26 17_07_52-Pit Boss temperature test 7-24-22 - Google Docs.png

I'm really looking forward to any advice that you all may have. Please feel free to ask me any questions that may help the discussion.

(I told you this wouldn't be short)
 
I'm looking for a little advice from folks that know a thing or two about the airflow in the Austin XL cooker. I think this would also apply to anyone that has one of the larger PB pellet grills (1000, 1100, 1150, & 1600) with this "large diffuser plate" that sits on top of and around the burn pot. It doesn't look like the small cookers have this same design.

View attachment 2941

At some point, I'm sure I can share the full report, but in an effort to keep this brief (which this probably won't be), here's what I discovered so far. I put the 4 Inkbird temp probes on the cooking grate like this, trying to get a feel for the temp differences across the grate from left to right:

View attachment 2942

And before people just say "buy the flame diffuser and/or heat deflector mods", please bear with me. I'm hoping to find a different solution that might work.

When I kept the PB diffuser plate installed, the right side of the grill was hotter than the left side by about 30-50 degrees. I also noticed that the Inkbird probe on the left side, closest to the Pit Boss temp probe, was typically 20-40 degrees hotter than the PB probe (so if the grill controller was set at 225, the left side of the cooking surface was 260, and the right side was over 300). I talked with PB customer service, and in addition to sending me a new temp probe, they suggested I try running the same test without the large diffuser plate.

So I went ahead and did the test, and low and behold, the hot spot switched sides. Or more accurately, the hot spot turned into a cool spot. First thing I noticed is the Inkbird probe on the left side practically matched the PB temp probe (I did not install the replacement that they sent me). So if I set the grill at 225, the left side of the grill was around 225. Great! But now the right side of the grill is 30-50 degrees COOLER than the left side.

So that got me thinking - can I just add some vent holes to this diffuser plate and find a happy medium?

My questions to you PB owners are:
1. Does this make sense? Is there any reason not to try this, knowing that once I drill some holes in this plate, I can't go back?
2. If it makes sense, where do you suggest I try drilling first (see picture below)? I'm not really sure where to start. I've thought about it a lot, and I keep going around in circles. I'm trying to take into account how the heat rises and circulates, how to make sure that the PB temp probe is reading the correct temperature, how to make sure I'm not creating a new issue, etc. If I had a couple extra of these diffuser plates, I would just starting drilling and see what happens, but I don't.

View attachment 2943

I'm really looking forward to any advice that you all may have. Please feel free to ask me any questions that may help the discussion.

(I told you this wouldn't be short)
Nobody ever replied? What did you end up doing?
 
I did end up buying the flame diffuser. What I didn't capture in my original testing data was the hot spot directly over the burn pot, and that needed to be addressed. For now, I'm not using that large diffuser plate and I really haven't done anything else with this project. I'm still playing around with covering the air gap by the temp probe with aluminum foil, but I'm not 100% sold on that yet. I've been doing more cooking than testing at this point, and I've been able to take advantage of the different temperatures on the grates to move the meat around as necessary.
 
I did end up buying the flame diffuser. What I didn't capture in my original testing data was the hot spot directly over the burn pot, and that needed to be addressed. For now, I'm not using that large diffuser plate and I really haven't done anything else with this project. I'm still playing around with covering the air gap by the temp probe with aluminum foil, but I'm not 100% sold on that yet. I've been doing more cooking than testing at this point, and I've been able to take advantage of the different temperatures on the grates to move the meat around as necessary.
If you start drilling holes.... electric boxes have knockout holes, there are also blinds to snap in existing unused holes. So if you use a step drill use a size that that you can plug.

I have a GMG with a diffuser similar to the one pictured above. It doesn't have the large hole in the middle. It seems provide even heat. I put 4 butts on it with no problems.
 

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