KopyKat
Well-Known Member
I learned something about thermometers that I didnt know. It all started with discrepancies between three thermometers I had for testing mash temp. A lab thermometer, a digital probe and an analog bimetal.
None of them agreed but I though that the lab thermometer because it was a glass thermometer would be the most accurate. I thought that is was a laboratory grade thermometer because it said lab thermometer on the box. For $6.99 you would have thought I would know better but nay, I thought it was lab grade.
To test, I bought two more glass lab thermometers and did the following experiment.
I took a 2 cup measuring cup and a 4 quart bowl. I filled them both with 150° water, putting the cup in the center of the bowl. I left it stand for at least 15 minutes for the water temp inside to stabilize. I put the three lab thermometers in the cup in the center and left them there for about 15 minutes then took a reading. I left them another 15 minutes or more and took another reading.
Reading 1 Reading 2
My older thermometer - 118° 111°
New thermometer #1 - 123° 116°
New thermometer #2 - 121° 114°
As you can see there is a 5° difference. Then I did the BYO calibration and found the following:
Boiling @ 211.5 ** Freezing at 32°
My older thermometer - 205° 30°
New thermometer #1 - 210° 32°
New thermometer #2 - 208° 31°
** Compensated for Altitude and Barometric Pressure.
This was pretty depressing and what was worse is that I discovered that at all temperatures it took several minutes for these thermometers to settle out completely to a stable temperature.
I took the two back that I purchased and went to Capitol Scientific nearby and ordered a true laboratory grade mercury thermometer. 0-180° with gradations of 1° per mark. $22.00 plus tax. They said it would read correctly within a few seconds at the most. It will be a week to 10 days before it comes in but it will be worth it to have a thermometer that is accurate and that I can calibrate other thermometers with.
Now some have said, just find out how much yours is off and compensate. Call me anal but nothing drives me crazier than things that dont work like they are supposed to. I will be happy to know what my temps really are.:rockin:
None of them agreed but I though that the lab thermometer because it was a glass thermometer would be the most accurate. I thought that is was a laboratory grade thermometer because it said lab thermometer on the box. For $6.99 you would have thought I would know better but nay, I thought it was lab grade.
To test, I bought two more glass lab thermometers and did the following experiment.
I took a 2 cup measuring cup and a 4 quart bowl. I filled them both with 150° water, putting the cup in the center of the bowl. I left it stand for at least 15 minutes for the water temp inside to stabilize. I put the three lab thermometers in the cup in the center and left them there for about 15 minutes then took a reading. I left them another 15 minutes or more and took another reading.
Reading 1 Reading 2
My older thermometer - 118° 111°
New thermometer #1 - 123° 116°
New thermometer #2 - 121° 114°
As you can see there is a 5° difference. Then I did the BYO calibration and found the following:
Boiling @ 211.5 ** Freezing at 32°
My older thermometer - 205° 30°
New thermometer #1 - 210° 32°
New thermometer #2 - 208° 31°
** Compensated for Altitude and Barometric Pressure.
This was pretty depressing and what was worse is that I discovered that at all temperatures it took several minutes for these thermometers to settle out completely to a stable temperature.
I took the two back that I purchased and went to Capitol Scientific nearby and ordered a true laboratory grade mercury thermometer. 0-180° with gradations of 1° per mark. $22.00 plus tax. They said it would read correctly within a few seconds at the most. It will be a week to 10 days before it comes in but it will be worth it to have a thermometer that is accurate and that I can calibrate other thermometers with.
Now some have said, just find out how much yours is off and compensate. Call me anal but nothing drives me crazier than things that dont work like they are supposed to. I will be happy to know what my temps really are.:rockin:
