Thermometers

[et700]

John, I have 3 thermometers around the house, 2 electronic and one old fashioned dial. This morning the temp was -30 on the dial one, -28.5 on one of the electronic and -25 on the other electronic. I have the outside sending units on the electronic ones within a foot of the dial on a post. The local reporting station had -29, about 4 miles away. Is there a standard that these are calibrated to? The electronic are two different brands. I find it curious there is so much disparity, and wonder how wide spread this is and what effect this has with more professional type units the reporting stations use. Maybe someone can elaborate too on what the electronic ones use to actually measure temps. Just curious on this, and you are my go to person for accurate info.
Thanks for all you do.

 

[steve_in_il]

I will be curious to see John's reply here as well. My take is that we get what we pay for with consumer thermometers and that they aren't exactly manufactured with high standards and tolerances. Your experiences et700 are a perfect example.

 

[et700]

Without a doubt your right Steve on that score. When I bought the dial one, I looked at all of the ones on the shelf, and picked one that the majority had as that temp. There were some that were way different for sure. I'm just wondering if the high quality models are calibrated and to what. I have no idea what these types use to measure the temp internally.

 

[scott_b]

I know it is different with these type of thermometers but with the dial type you use for cooking you can calibrate them by placing the thermometer in ice water or boiling water and turning the frame of the dial until it is at the right temp. I have done this a few thermometers in setting up my draft beer system. Not sure about calibrating a digital thermometer.

 

[eyeman]

I know it is different with these type of thermometers but with the dial type you use for cooking you can calibrate them by placing the thermometer in ice water or boiling water and turning the frame of the dial until it is at the right temp. I have done this a few thermometers in setting up my draft beer system. Not sure about calibrating a digital thermometer.

Don't forget to take into consideration elevation. Water boils at 208 degrees at 2000 feet above sea level and 195 at 10,000 feet asl.

 

[jd]

I would have to agree on the idea that you get what you pay for. The dial thermometer most likely works off of a bi-metal strip. The strip is made of two differing metals that have different expansion and contraction rates based on temp. Those types would most likely be the least accurate.

I am surprised the electronic sensors were so far apart in their readings, but again, if they were not very expensive, then might not be too accurate.

The most accurate way to measure is with a well built mercury thermometer.

-John