Interesting thermometer observation

[Guest]

Hey guys:

I just received my Remote Check wireless thermometer which accepts two probes and lets me monitor both without standing outside by the cooker.

I'm in the middle of doing a couple slabs of babybacks on my Weber kettle conversion smoker. Since I can't put a thermometer in the meat, I thought I'd play around with two thermometer locations inside the cooker and see the temperature variations.

I have both thermometers at the grate level. Probe #1 is shoved through a potato and sitting on the grate about halfway between the sides of the cooker and the center of the grate. Probe #2 is inserted through a cork which is plugging a hole in the side of the cooker. The tip of this thermometer is located about six inches in from the side -- in roughly the same position as the other probe, but the stem of passes through the hot region near the side of the cooker.

This second probe has been consistently running 30+ degrees higher than the potato probe. (Both probes were within 1 degree of each other in boiling water).

The sensor in these probes is at the tip, but apparently there is sufficient heat transfer along the metal stem of the probe to really change the reading.

It's kind of a shame actually, because inserting a thermometer through the side of the cooker is a very convenient way to measure temperature at the grate. But, it apparently isn't particularly accurate unless you factor in an adjustment.

 

[Guest]

As luck would have it, right after I posted the above message (the 3 hour mark in cooking the ribs), the temperatures betweeen the two probes got much closer and stayed that way -- with only a 5 to 10 degree difference. Apparently, the hotter the fire, the more the spread between the two.

Anyway, the ribs were outstanding. I cooked them for 5.5 hours and the meat just melted off the bones while eating them. No trace of burned ends or any black char on the outside. Just a deep uniform mahogany-colored outside. Perfect.

Here are the time and temp readings (center of the grate):

1:30 230
2:00 232
2:30 243
3:00 242
3:30 239 basted and turned
4:00 239
4:30 233 basted - stirred charcoal
5:00 244
5:30 230
6:00 228 basted and turned
6:30 229
7:00 223 done

These temps are with no water. It didn't impact the final product, but I would like to be able to hold the cooking temp a little lower. I think that will be possible. I've got major "out of round" air leaks going on where my "smoker ring" joins the kettle -- fairly close to the fire. These leaks are sufficient that the fire won't go out with all the vents closed, so I suspect they are keeping my temps up a bit.

I've got a modification in mind to achieve a tighter seal and see where that puts me.

After holding temps in the 230-240 range for 5 hours, I took the ribs off and wanted to crank the heat up a bit to finish roasting some baked potatoes. I opened the vents (with a fairly modest fire at that point) and had no trouble bringing the temp up to 330 degrees at the grate where it held steady for 45 minutes with the bottom vents half open.