Accuracy of Digital Thermometers?
In advance of the holiday cooking, I am checking the accuracy of my digital thermometers. Sitting in a jar of warm water, three thermometers show three different temperatures -- a full 10 point difference. Ten points means a lot, to say the least, when roasting meats. Any similar experiences? Any advice?
The three thermometers all are relatively new, used frequently, and name brands.
Boil some water and check what temperature the thermometer reads. Do it a few times to ensure the thermometer is consistent, and then just adjust. If it was me, I'd actually return any that didn't have water boiling at 100 (Celsius, I don't know Fahrenheit)
The only digital thermometer I have ever owned was a gift purchased from Williams-Sonoma. I made a roast chicken with it which turned out overcooked. I never overcook a roast chicken without a thermometer. I looked up the thermometer on their site and the reviews for it were terrible and had similar overcooked item stories. The gift giver had included a gift receipt so I exchanged it for a nice set of nesting bowls and various other gadgets. I've never felt the need to buy another one after that experience... I seem to do fine without one.
The most reliable way to check a digital thermometer is the ice water test.
"Ice Water Method - Fill a large glass with finely crushed ice. Add clean water to the top of the ice and stir well. Immerse the thermometer stem a minimum of 2 inches into the mixture. The thermometer should read 32 degrees F after 30 seconds. "
There are several issues:
- precision (how fine of differences can it detect)
- response time (how long it takes to settle to the new temperature)
smaller tip thermometers are supposed to have a quicker response
- calibration. Better thermometers meant for food service use can be calibrated, adjusted to match ice water and boiling water temperature.
I suspect there were 2 issues with your 3 - different response times, and being off on calibration. And when you compare temperatures, make sure the water (or what ever) has a uniform temperature (or is well mixed). There can be different temperatures in a pot of water depending on how close the sides you measure, and how close to the bottom or surface.