Weber Kettle Temps (Indirect) At Different Levels

[fuzzydaddy]

Today I did a test on my 22' Weber Kettle to see how much higher the temp is up in the dome vs the cooking grate, with an indirect setup using the Slow ’N Sear. Due to quickly approaching storms I was only able to test 1 level in addition to the cooking grate.

My setup:

• 22” Weber Kettle.
• Kingsford Blue Bag, 12 lit, with about 1/2 chimney total.
• Slow ’N Sear with about 2 cups water.
• Exhaust vent opposite the SnS.
• Weather: 94 degrees, little to no wind, and the Kettle was in filtered sun.
• First level was 1” above the cooking grate.
• Second level was 5” above the cooking grate, using a grate with legs.
• Probe tips were as close to the same position (horizontally) as I could get them, and about halfway between the charcoal and the other edge of the kettle (~7” from each point).
• Nothing else was in the kettle.
• ThermoWorks Pro-Series High Temp Air Probes With Grate Clip, ChefAlarm and DOT.
• Test temperature target 225 (low-and-slow).

For reference, once I was up to 225, with both probes 1” above the cooking grate and within 1” of each other, the probe readings differed by 2 to 3 degrees.

• First reading 225 and 227.
• Second reading, 20 minutes later, 228 and 231.

I then moved one clip/probe to the 5” level, put the lid back on, and allowed the temperature to settle back to 225 at 1” above the cooking grate. I made no more vent changes and waited 5 minutes for the first reading.

Readings are 1” above cooking grate & 5” above cooking grate, in 5 minute intervals.

• First reading 225 and 285 (60 degrees difference).
• Second reading 223 and 280 (57 degrees difference).
• Third reading 221 and 276 (55 degrees difference)..
• Fourth and final reading 219 and 271 (52 degrees difference).

If I test again, I’ll make sure that I’m better stabilized at 225 before I start the test. Temps dropping at the grate was not intentional. Next time without storms nearby.

I hope this is helpful information and if you do any similar Kettle tests, feel free to add to this thread.

David (FuzzyDaddy) Polston

[JeffJ]

Well, well....the new moderator is getting all scientific. :-)

It's amazing how much of a heat difference there is in a kettle as we move above the grate. A couple of months ago I did 2 slabs of SLC in a 22 kettle with SnS. They barely fit and I actually had to place the side of one if the ribs up on the handle of the grate - maybe 2 inches above. A couple of hours later it was visibly more cooked than the rest of the meat. It's important to keep that in mind when utilizing a hover-grate.

[fuzzydaddy]

:-) Agreed. When I smoke Boston Butts I always flip them when adding charcoal for even cooking and bark. I thought it was time to see some numbers and I love numbers.

[CeramicChef]

fuzzydaddy - the thermodynamics and heat transfer aspects of this make perfect sense to me. I'm a Chemical Enginerd. The temperature gradients in your kettle will be greater the more direct sunlight on the kettle, ceterus paribus due to more energy input from more sunlight. Nicely done!

[Mosca]

And this agrees with my observation yesterday during my inaugural rib cook on the kettle. When the grate temp was 250, the dome temp (by the dial thermometer) was between 325 and 350.

[Huskee]

Almost always the dial therm will read ~75 degrees hotter than the grate on the indirect side. Very useful to know in case your digital ever gives out on you!

[Potkettleblack]

Is it possible that kettle thermometers and gasser thermometers behave differently? We know that closing lid on a gasser drives temp up, while kettle, it chokes the fire down for cooler convection. My lid thermometer is usually within 5 degrees of my indirect side grate temp.

[Huskee]

fuzzydaddy I've found very similar results in my tests, thanks for posting! Even 1 measly inch higher than the Maverick clip will often yield 30 degrees higher! Thsi is why the top of a chicken will darken up more than the grate-level parts.

On your next 225 cook, stick your Thermapen into the exhaust vent, an inch down and then as far as you can. Those results will surprise you.

[martybartram]

mmmm roadkill

[Huskee]

CeramicChef Yes, I'm referring to spatchcocked.

[Potkettleblack]

Might be useful in vertical roasting, if you could do it upside down to get more heat on the dark meat. That would be the no-can chicken of all time.

[Skinsfan1311]

I have a constant ~70deg difference, between dome and grate, and it's been like that for years. It's good to know that the old bi-metal isn't too far off. I use it, a lot, when I'm feeling lazy, especially for reverse sears.

[David Parrish]

If you know your cooker this technique works great. I use it when I'm lazy myself =)

[Fine Swine]

How about testing at the grate level close and away from the slow n sear? Perhaps even below and above too? Makes sense to me that you would find some drastic changes in temps. Then do the test with a whole turkey with a bunch of probes everywhere. A few turkey cooks ago, I was surprised to see some differences with my thermopen from left and right. So I rotate the bird and all is well.

[fuzzydaddy]

Readings I did some time ago was maybe 5 to 15 degrees different closest-to and farthest-away from the SnS and after a while into the long cook (butts) it reversed. Initial reading was cooler next to the SnS water reservoir. I would guess maybe 50 or more degrees cooler on the charcoal grate, but I could be wrong.