I’m assuming you’re talking about permanently mounting a dial thermometer through the lid. If so, Tel-Tru and Ashcroft both put out quality products and you can’t go wrong with either choice. As for dial sizes, temperature ranges, and other bells and whistles, that’s up to personal preference.
Measuring the temps at grate level is a vague and possibly misleading term. Depending on variables such as how much food you’re cooking, where it’s placed and how it’s arranged, whether anything’s on the bottom shelf, and so on, the temperature at the outside of the grate may be 25 degrees or more higher than that at the center of the grate.
As for the plusses and minuses of mounting at grate level, here are the first few that come to mind.
Pros:
- Knowing what the temperature is at that one particular spot at the grate level.
- No chance of the batteries in a digital thermo dying mid-cook or its electronics getting wet.
- No risk of the digital probe’s cable getting fried due to exposure to high heat.
Cons:
- Having the stem touch the food and give inaccurate, lower readings.
- Having the stem interfere with getting your food in and out.
On my Bullets, I have thermometers with 2 1/2” stems mounted a couple inches above the grate. If I were to do it again, I’d mount them much higher on the dome to reduce the possibility of the stems touching the food.
Regardless of where you choose to mount your thermometer, on the first cook after installing it I’d recommend bringing your WSM up to temperature, put the food on, and let the temperature stabilize. Then, compare the thermometer’s reading against that of a probe in the center. Knowing what the differences are between those readings, you can then adjust your target temperature accordingly to average out the difference.
Then, relax and enjoy the process of cooking something wonderful to eat. Only rocket science should be as complicated as rocket science.
Hope this helps.
Ken