Thermometer 'calibrating ' Help.......

[symphony1975]

hello,

after reading an article on calibrating thermometers i thought i would give mine a whirl. i have 2 glass/bulb thermometers and a tempmate.

i got a stainless steel thermowell to slide my tempmate probe in to use for my HLT water and in my esky mash tun and wanted to see how differently it reads to the bulb ones.

i followed the articles instructions and measured temp in iced water, boiling water on stove and various intervals inbetween.

i used tap water and live in belgrave, melbourne.

this is what i got:

tempmate bulb thermo 1 bulb thermo 2

.9 1 .5 -iced water
X 98 97 - boiling water (in thermowell, tempmate probe got a bit hot.....oops)
78.2 76 75
59.2 57 57
36.9 36 36
27.1 27 26
24.1 24 23
20.5 20.5 20

so the higher the temp the more discrepancies.

my questions are:

is the reading at boiling temp being a few degrees under 100 due to altitude?

if i wanted to use my tempmate to read specific strike water and mash temps, how would you compensate/read these results?

i am new to AG and just wanted to get off to a good start......cheers

 

[MHB]

I think you are asking good questions, the altitude question you will have to answer yourself as I for have no idea how high you are.
That said you can expect a bit of a loss in an open thermo well.
Remember thermometers come in two sorts, Total and Partial Immersion, the error for using them the wrong way is about 3oC at boiling so it might be a good idea to read the back of the thermometer or see if it has a line around it, about 76mm (3) from the tip or says total or partial immersion.
Even if the temperature is a bit out, its important to be consistent, so choose one of the bulb thermometers and use it as a reference, if you beer is a bit sweet or dry adjust accordingly.
Hope you make lots of great beer
Mark

 

[symphony1975]

I think you are asking good questions, the altitude question you will have to answer yourself as I for have no idea how high you are.
That said you can expect a bit of a loss in an open thermo well.
Remember thermometers come in two sorts, Total and Partial Immersion, the error for using them the wrong way is about 3oC at boiling so it might be a good idea to read the back of the thermometer or see if it has a line around it, about 76mm (3") from the tip or says total or partial immersion.
Even if the temperature is a bit out, it's important to be consistent, so choose one of the bulb thermometers and use it as a reference, if you beer is a bit sweet or dry adjust accordingly.
Hope you make lots of great beer
Mark

thanks for the advice mark.

i had a look at my thermometers and the only mark i could find is the one shown in pic below. is that possibly the immersion line? i didn't fully immerse them when i did the boiling water test the other day so i did the test again and i got:

thermometer A- 100 degrees ( last test was 98)
thermometer B- 98.5 degrees ( last test was 97)

so 2 degrees higher than when i did the test last week.

but is it incorrect to lay the thermometer down in the test water? should it be upright and immersed? and is it right that these sort of thermometers should be stored upright also?

cheers again for your help.....