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Thermapen vs thermometer from candy kit.


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#1 glennbech

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Posted 31 December 2013 - 06:01 PM

For xmas, i bought one on of those kits for hard candy making; and got a thermometer that goes from 0 to about 200c. (32-400f) 

Today I did some deep frying and kept an eye on the oil with both my Thermapen (accurate to +/- .4c) and the thermometer from the candy kit.

 

The candy kit was off by almost 10c below actual. (50f) !!! This is pretty bad isn't it? We probably did the candy all wrong, stopping the sugar at 10c below target temp.....

 

 



#2 hattermad

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Posted 02 January 2014 - 03:06 AM

Just to be clear - being 10C off is only 18F, not 50F. 9/5C + 32 = F is the conversion, but for differentials the + 32 does not apply as it cancels out.

 

That said, I think being 10C off is pretty bad, IF you were measuring at the target temperature for candy making. I personally use a thermapen and have found it accurate across a range of temperatures, but I have specific thermometers which match the thermopen at some points but then sail off wildly as they get further away from their intended target range. If the thermometer is 10C off at the temperature it's intended to target, it's nigh on useless.



#3 glennbech

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Posted 05 January 2014 - 04:29 PM

Just to be clear - being 10C off is only 18F, not 50F. 9/5C + 32 = F is the conversion, but for differentials the + 32 does not apply as it cancels out.

 

That said, I think being 10C off is pretty bad, IF you were measuring at the target temperature for candy making. I personally use a thermapen and have found it accurate across a range of temperatures, but I have specific thermometers which match the thermopen at some points but then sail off wildly as they get further away from their intended target range. If the thermometer is 10C off at the temperature it's intended to target, it's nigh on useless.

 

Thanks for pointing that out.

 

The sugar thermometer is about 10c off in the 200c range, and about 5 when I measure at 60c.... Useless. I probably need to re-do my hard candy recipes to see if this had any effect on the result.



#4 Norm Matthews

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Posted 05 January 2014 - 05:50 PM

I'd tend to trust the candy thermometer more than the thermapen.  The candy thermometer is in the middle of the boiling liquid and measuring the ambient temperature while sometime i wonder if my Thermapen is measuring the surface of the liquid or the bottom of the pot.  That little red dot isn't stopping in the middle of the batch.



#5 keychris

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Posted 06 January 2014 - 10:26 PM

If you've checked the calibration on your thermapen, I'd trust that (I'm assuming you're talking about one of these: Thermapen)

 

sometime i wonder if my Thermapen is measuring the surface of the liquid or the bottom of the pot.  That little red dot isn't stopping in the middle of the batch.

 

If you're using an IR thermometer, it's measuring surface temperature. The dot is purely for your visual reference where you're aiming ie. the dot isn't doing the measurement, rather it's pointing at the spot that is being measured. IR is the only type I know that has a red dot :D