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Q-talk *ON TOPIC ONLY* QUALITY ON TOPIC discussion of Backyard BBQ, grilling, Equipment and just outdoor cookin' in general, hints, tips, tricks & techniques, success, failures... but stay on topic. And watch for that hijacking.


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Unread 02-10-2013, 04:20 PM   #1
dwfisk
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Default Temperature Variation in Stickburners

Been following a very good new build thread by bfraze99 and rather than hijack his thread I though I would start a new one to explore a couple questions.

How do you measure variation across the cook chamber in an offset stickburner, either traditional or reverse flow? I do a couple of things with mine: I have a dial thermometer at about the center and I usually make one of my 2 iGrill probes and ambient cook chamber probe. Fortunately they agree within a couple degrees. To measure variability across the cook chamber I wait until the pit has been up to temp for a couple hours and then I using my infared thermal gun I check temp at 6-8 spots on the outside of the cook chamber. What I'm seeing is when I'm holding my target 250* in the cook chamber based on the dial and iGrill ambient probe, the temp measured on the outside with the infared gun is a few degrees cooler and only varies 5*-10* across the pit, say from 230*-235* or 240*. I'm assuming I have a comparable 5*-10* variation inside the pit. Do you think this method is giving me viable data?

That begs a second question: what is meaningful variation when it comes to making decisions relative to cooking strategy? I think I would argue different devices varying by a couple degrees is irrelivant and temp variability across an offset stick burner of 5*-10* is no big deal.

Bottom line for me is the Q I'M getting seems to confirm I'm cooking at target temps I have pretty consistent temps across the pit (no super hot or cold spots).

What do y'all think?
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Unread 02-10-2013, 04:35 PM   #2
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That's pretty high tech for an old country boy like me. I use a pair of $5 oven thermos and a few cans of pop biscuits. I have mine dialed in with in 5 deg end to end and front to back and it don't get much better.
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Unread 02-10-2013, 04:50 PM   #3
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Sounds like you are on-track.... Consistent Temperatures are one of our goals.
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Unread 02-11-2013, 08:28 AM   #4
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You don't need fancy thermometers to tell you that a stick burner is hotter near the fire box. And like you said it ain't no big deal.
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Unread 02-11-2013, 11:53 AM   #5
bfraze99
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Default temp variation test

The temp variation should be hotter at the firebox as stated in earlier threads...

But can we use a deflector plate (like a tuning plate) to harness the energy and move it to were we want it.. ie: if the fire box is hot and we want to keep the heat near the fire box and direct it to the top of the smoker so we can draw the heat across grate to the exhaust hole... and limit the hot spot to say 3 or 4 inches from the firebox were we will ultimately end up at out given variance of say 20 degrees or less from the center of the pit? end the exhaust end will benefit because we are redirecting the high heat area to the top to come across to the cool end of the pit.

In my chitty drawing you can see the theoretical heat flow.. and the bottom deflector to keep the high heat back from grate and flowing up to cause the convection....

This should give you greater heat control and less variance?
Or am i completely off track here?
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Unread 02-11-2013, 01:34 PM   #6
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Quote:
Originally Posted by captndan View Post
You don't need fancy thermometers to tell you that a stick burner is hotter near the fire box. And like you said it ain't no big deal.
Well, here is a curious observation: when I'm set up as a traditional offset with the tuning plates adjusted, I have a small hot spot near the firebox BUT when I'm set up in reverse flow mode (almost always), I think I'm seeing my hot end is opposite the firebox where the heat exits the baffle & tuning plates. I've even confirmed it with a couple of oven thermometers inside the box. Thats why I asked if the way I'm measuing temps is worth a chit. Oh yea, I usually put a pan of apple juice or water on the tuning plates and maybe that also acting as a hot spott damper. Granted, I think I'm only seeing 5*-10* across the smoke chamber and I'm pretty content with that.

PS: thanks to Bludawg. I think I saw in another post that you preheat your wood and just add one ot two splits when the temp drops 25* from your target. I tried that and it works great.
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Unread 02-11-2013, 06:38 PM   #7
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On a reverse flow, just by lifting or lowing one end you can change your hot spots, or even them out, whichever you need. I can dial mine in to 5' variance if needed, most of the time if it is within 20' I am happy.
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Unread 02-12-2013, 10:00 AM   #8
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You can do the tilting maneuver with a standard offset...putting a couple bricks under the stack end will even out the temps quite a bit.
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