First off, let me say that I don't care for digital thermometer calibration. Or maybe I just don't care to calibrate mine. And, truly, you don't have to calibrate these digitals very often...they work well.
I have a CDN DTQ450...which I believe is a pretty common model. The problem, though, is that they don't calibrate at boiling. You have to calibrate them at freezing.
And, while it's not really obvious, a couple minutes thought and you'll realize that's damned hard to do. If you have a drink filled with 32F ice cubes, the fluid is a mix of the 32 degree ice cubes and the ambient air temperature...it's hard to get a real, solid (pun?) 32F reference source.
The best you can do is to fill something with crushed ice and the minimal amount of water. Crushed ice...little water.
See below....mostly crushed ice and you can see that the temperature appears to be just a bit off. I think it's safe to assume that my reference source (the bowl of crushed ice water) isn't below freezing or it'd be solid, right?
So, anyway, use your crushed ice and a little fluid and try to get as near to 32F as you can...then hold the CAL button for a couple seconds. The thermometer will display 'CAL' and then show 32F, like below.
So get a pot of water with a good boil, insert the thermometer, don't touch the sides or bottom. Give it a few seconds to calm down and it should show 212F.
Anyway, on brew day I like to have an analog and a digital both calibrated and ready to go. I'm not sure why. It just comforts me. That's all I need to know about it.
I need to say ice and water is not 32 degrees it is 36 degrees they told you wrong. I calibrated it to 36 degrees. with water and ice at room temperature it is imposeble to be right at the freezing point because when ice is melting at room temperature the water and ice is going to warmer than the freezing point because of the warmer air. when you put your thermometer back into a refrigerator after you calibated it to 36 outside the icebox put a jug of water in the icebox with the thermomerter. then as you lower the temperature in the refrigerator you will see the water will start to freeze when youre calibrated thermometer reads 32 in the icebox proving that ice and water melting at room temerature is not 32 it is 36 degrees
ReplyDeleteInteresting. That's, pretty much, in direct contradiction to every physics textbook I own...and every site I've seen.
ReplyDeleteBut...common wisdom being what it is, I think I'll try your experiment...I'll calibrate a couple thermometers, let one freeze up, see if it reads 4 degrees below zero.
...back to you soon.