Liquid Cystal Thermometer

[nicklawmusic]

I have one of those stick on LC (liquid crystal) thermometers that goes up in multiples of 2s (C). Exactly how reliable are they?

I am currently fermenting a stout and when I've taken hydrometer readings, the LC thermometer has shown something around 16-18c. But when I've used a spirit thermometer in my test jar, within a minute or so of extracting the beer, the temperature has shown 23c.

I'm using Nottingham, which is pretty robust temperature-wise, but not that robust! I'm concerned that my LC thermometer isn't doing the job right. Or is it that, in the test jar, it's going to be warmer because the volume of liquid is in a more concentrated area? (I'm no science whizz!).

Finally, are there any other methods of keeping an accurate temperature?


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[sptaylor70]

I haven't been impressed with the stick-on thermometers.

In a stout, a little more fruitiness from your Nottingham is probably going to be fine. Might even be an asset.

Temperature is not volume-dependent.

How much do you want to invest in accurate temperature readings? The best way would be to have either a digital thermocouple or a mercury thermometer* in a thermowell** submerged in the beer. Not quite as good is to place your fermentation vessel in a water bath or temperature-controlled refrigerator, with a thermometer/thermocouple monitoring the temperature of the bath/refrigerator.

* Mercury thermometers are generally more accurate than spirit thermometers.
** A thermowell is just a pocket that the thermometer/thermocouple sits in. It has a smooth surface, so it's easier to santize, and the interface between a thermowell and your cap can be made gas-tight more easily than can the interface between your cap and a thermometer/thermocouple.

 

[nicklawmusic]

How much do you want to invest in accurate temperature readings?

I don't know! How much does it matter?


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[helibrewer]

I don't know! How much does it matter?


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I consider it the most important thing for quality and consistency. You should make the temperature control as tight and as accurate as you can afford, ideally using fermentation chambers and controllers with thermowells. It's a matter of space and money, if you have both it's easy

 

[JDGator]

I have one of those stick on LC (liquid crystal) thermometers that goes up in multiples of 2s (C). Exactly how reliable are they?

I am currently fermenting a stout and when I've taken hydrometer readings, the LC thermometer has shown something around 16-18c. But when I've used a spirit thermometer in my test jar, within a minute or so of extracting the beer, the temperature has shown 23c.

I'm using Nottingham, which is pretty robust temperature-wise, but not that robust! I'm concerned that my LC thermometer isn't doing the job right. Or is it that, in the test jar, it's going to be warmer because the volume of liquid is in a more concentrated area? (I'm no science whizz!).

Finally, are there any other methods of keeping an accurate temperature?


Sent from my iPhone using Home Brew

i have 2 stick on thermometers on each of my brew buckets and most always read the same. but i do have one that seems to be off by 2F. not the end of the world but i do keep that in mind.

maybe check your other thermometer and see if it's out at all.

 

[Trox]

I don't know! How much does it matter?


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If you are trying to hit a specific style the same way every time then it is extremely important. If your like me who just wants too brew good/great beer and don't mind (actually prefers) eac batch being a bit different then a few degrees either way isn't going to hurt anything. If it was 8-10 degrees off then I would be a bit concerned.

 

[Wynne-R]

I just pulled 110 mL of 17 C beer into a sample tube with hydrometer. It stabilized at 20 C. My apartment is at 24 C, so the beer would be warmed by my turkey baster, the sample tube and mostly the hydrometer. This is with a narrow sample tube and a 44g precision hydrometer. My regular tube uses a 200 mL sample and a general purpose 24 g hydrometer, so the difference would be about half.

If you’re rocking 6C, something is wrong. The liquid crystal is a chemical reaction, it should be as accurate as you can read it. Then again, an analog liquid thermometer should be as accurate as you can read it, about ½ C. It seems one or the other is defective, maybe both.

I don’t know of any reason that mercury would be better. The less toxic replacements are quicker. The liquid is almost certainly not alcohol, which boils at 72 C.

Periodically I get my thermometers together to see if they all agree. See if you can borrow one that is known accurate. If you use an ice bath, make sure there’s more ice than water, and stir it.

 

[sptaylor70]

If truly neutral flavor from your yeast and/or reproducibility is vital (e.g.you're going to enter your beer in a competition), then temperature control to within about 1 degC is where you need to be. If you're brewing Belgian- or English-style ales, and they're just for you and yours, then 2-3 degC (or more) will get the job done.

In our lab, we've observed that alcohol thermometers (and the liquid is an alcohol) can be as much as 2 degC off. In analytical laboratories, mercury thermometers are the name of the game (unless you need automatic recording, in which case thermocouples are the standard).