I've been using my 14.5 WSM for almost a year now. It gave me something new to play with since the pandemic started. Since I started using it I always monitored the WSM temperature through the grommet by sticking my Thermoworks smoke air probe through the single hole. Recently I cut a notch on the top of the smoker to run wires so I tried monitoring the temperature on the top grate and through the grommet using two air probes.
I cooked a 4.5 lb pork butt with 4 cups of water in the pan with B&B charcoal. It was a nice day in the low 80s and no wind. I placed the air probe about 2 inches from the meat. Initially, for the first 1-2 hours the temperature measured through the grommet was about 10-15 degrees F greater than the grate temperature (235F vs 245-250F). At that point both temperature probes reported the same temperature and they remained steady for another couple of hours (250F). Eventually the grate temperature began to exceed the grommet temperature (5-10 degrees) and that remained consistent at least until I wrapped the meat. I wrapped the meat when the meat temperature reached 167F and at that point I discontinued the experiment (about 5-6 hours in). I decided to continue monitoring at the grate for the duration.
On occasion I also checked the dome temperature and that ran about 25 degrees lower than the grate temperature but I take no stock in its measurement.
The biggest thing I observed was that the grate temperature seemed more stable compared to previous cooks measuring through the grommet. I had to made fewer adjustments to maintain a constant temperature. I was also able to keep the top vent wide open where previously I had to close it to 75% open along with needed adjustments with the bottom. This time I was able to close two bottom vents completely and leave the third bottom vent open 1/4-1/2 open throughout.
My guess is that the grate temperature was lower initially was due to its proximity to the cold meat and the measurement through the grommet was initially higher since it was exposed to the rising hot air along the sides of the cooker.
I cooked a 4.5 lb pork butt with 4 cups of water in the pan with B&B charcoal. It was a nice day in the low 80s and no wind. I placed the air probe about 2 inches from the meat. Initially, for the first 1-2 hours the temperature measured through the grommet was about 10-15 degrees F greater than the grate temperature (235F vs 245-250F). At that point both temperature probes reported the same temperature and they remained steady for another couple of hours (250F). Eventually the grate temperature began to exceed the grommet temperature (5-10 degrees) and that remained consistent at least until I wrapped the meat. I wrapped the meat when the meat temperature reached 167F and at that point I discontinued the experiment (about 5-6 hours in). I decided to continue monitoring at the grate for the duration.
On occasion I also checked the dome temperature and that ran about 25 degrees lower than the grate temperature but I take no stock in its measurement.
The biggest thing I observed was that the grate temperature seemed more stable compared to previous cooks measuring through the grommet. I had to made fewer adjustments to maintain a constant temperature. I was also able to keep the top vent wide open where previously I had to close it to 75% open along with needed adjustments with the bottom. This time I was able to close two bottom vents completely and leave the third bottom vent open 1/4-1/2 open throughout.
My guess is that the grate temperature was lower initially was due to its proximity to the cold meat and the measurement through the grommet was initially higher since it was exposed to the rising hot air along the sides of the cooker.
