I have an Arduino Yun and I brew beer.

I would like to log the temperature of the beer at all time during the fermentation process (final stage). This means the thermometer would have to remain in the beer during this time (10 days). The temperature would be < 40 degrees Celsius (probably around the 20 degree mark).

Question: What temperature sensor would be best suited to this task?

It must be:

  • Food grade
  • Can be used in alcohol for extended periods
  • Can be hooked up to Arduino (i.e. add a library and ready to go)

Thanks, Dan.


You are looking for a thermocouple.

They need some specific chip to be read, so you'll probably want to spend a bit more and get a chip with a digital interface, there are some witch has arduino library, like MAX6675 (output at 1Hz, 0.25° precision).

As this chip read "C type" thermocouple, you just have to find the right probe for your needing, with probably can be found in many specialized store.

You may even buy a normal k probe, and then wrap it up in some protective case. Obviously that case should be designed to let the heat flow easily, but without short circuiting the probe; a food plastic bag;

or just spend a little more money and buy a stainless steel probe

  • Thanks - I will take a look at thermocouples (new term for me thanks). I don't mind spending a little bit of money. I would prefer not to use plastic bags due to the fact there will be an aquarium heater in the container also.
    – DanAbdn
    Mar 4 '15 at 20:59
  • yeah, the chip can be found for 10-15$, the probe i think others 30-30$, because you need to be sure it is food grade. Please try to spend a bit more but stay safe. And remember to calibrate it putting in ice and boiling water, and/or using a better quality thermometer; it is fine to have to compensate for a bit of error
    – Lesto
    Mar 4 '15 at 21:10
  • 1
    A Thermistor is what you are really looking for, I would downvote this answer but I don't have the rep here to do so. A thermistor is a type of resistor whose resistance varies significantly with temperature, more so than in standard resistors. On the other hand, a thermocouple is a temperature-measuring device consisting of two dissimilar conductors that contact each other at one or more spots, where a temperature differential is experienced by the different conductors (or semiconductors). Two differnt technologies, for your usage you are really looking for the thermistor.
    – Tyson
    Mar 5 '15 at 3:28
  • 1
    A thermocouple generates a few millivolts of current, and is most typically used in the flame of a pilot light and connected to a fail-safe gas valve. On the other hand a thermistor must be powered by it's circuit and is much more useful at 20-40C than a thermocouple.
    – Tyson
    Mar 5 '15 at 3:36
  • 1
    @tyson write it as your own answer, not as comment. I don't think a thermistor is better as it is slower and with less precision.
    – Lesto
    Mar 5 '15 at 7:32

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