[BROe]

I own an alcohol thermometer with a supposed effective range of -20C - 240C. Several weeks ago I used this thermometer to distill ethylene glycol, this was the last time it functioned properly. Yesterday I took it out of storage to find that it was reading a temperature of below -20C, obviously wildly incorrect since it was inside my house for most of the intervening time. I have tried placing the thermometer in boiling water and it read the temperature as 45C and then returned to reading below -20C after cooling to room temperature. I have found lots of fixes online for separated alcohol columns or temperature readings being too high, however I have not found anything for consistently low temperature readings. Any suggestions on how this might be fixed would be appreciated.

[Arkcon]

If the alcohol is separated within the thermometer, you should see that -- i.e. the suspicious gap between two columns of red liquid.   You have to know why that happened -- either mechanical separation, giving you two columns of red liquid, or you got it too hot, and the liquid has collected in some sort of upper reservoir, or the tube ruptured and leaked.  Cooling well below its lower rating might join the columns of liquid, and centrifugation might help join the columns of liquid.  But this thermometer may be a lost cause.