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Temperature measurement accuracy

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Newts

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Hi all,

Just a question regarding temperature measurements whilst brewing and how reliable the equipment being used actually is. I brought a few of the these thermometers off Ebay mainly due to the price:

http://www.ebay.com.au/itm/Digital-LCD-Probe-Fridge-Freezer-Thermometer-Thermograph-for-Refrigerator-110-/300835102158?pt=AU_Decor_Furnishing&var=&hash=item460b2b5dce

I'm just wondering how I can tell if it's actually measuring the correct temperature - I put it in an ice bath and it came fairly close to zero which would be expected but really I don't know what to compare it to to find out if it can measure temps between 60-100 degrees. I'm looking at steeping spec grains and my understanding is the temperature is important which is why I ask the question.

Does anyone have any methods they use to make sure temps are correct? Or does anyone have any input on the ideal way to measure temperature or the gear that should be used? Are certain types thermometers considered more reliable - for example mercury thermo vs. digital thermo?

Cheers guys,

Newts
 

avaneyk

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The temperature for steeping speciaty grains (crystal, roasted malts etc) is actually pretty forgiving - between 60 and 70 degrees will be fine. Its more important to have reasonable accuracy when mashing base malts because the mash temp determines the fermentability of your wort. With specialty malts the mash was done already by the malt manufacturer.

To check your thermometers at higher temps - measure boiling water - it should read 100 degrees. If not, just factor in the difference when your measure you hot water.
 

gsouth82

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I work with a lot of different sensors including temperature and unless you have a calibrated reference probe, there's not an easy way to check your probe is correct.
My suggestion would be to place the probe into an ice bath to get a 0°C reading. Then place it into boiling water to get a 100°C reading.
If at 0°C your probe is reading say 1°C and at 100°C its reading 101°C then you can easily apply a 1°C offset, that is assuming your sensor is linear.
A 2 point check isn't the most accurate and 3rd 'mid' point should be used but a reference probe is usually needed for this.
The other issue is that your not really concerned it the probe reads correctly at 0 or 100°C, your more interested in the 60-70°C range. This is where the 3rd mid point should be taken if possible.
In saying all that, it really depends how anal you want to be. I checked the ebay ad and the seller claims the probes are accurate to +/- 1°C. In my opinion, this is an acceptable error for steeping and fermenting. If you wanted to spend more, you might be able to get something more accurate.
That's my 2 cents anyway.
 

WarmBeer

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Stick it in your butt. Should read between 37.3 and 37.6 degrees.

Assuming you're not running a fever at the time.
 

QldKev

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I recommend all brewers getting a reasonable quality alcohol filled thermometer as a calibration unit. Something like this one, $12.95 from ebay posted. I have that one and they are very clear to read, a lot better than that pic looks. The calibration one is used to check / set your digital ones etc at mash temperatures etc. Then you put the glass one away before you break it, and play with the harder wearing one.

If you do use WarmBeer's method of calibration remember to wash it before putting it in your beer :p
 

NewtownClown

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QldKev said:
If you do use WarmBeer's method of calibration remember to wash it before putting it in your beer :p
What? DON'T wash it before putting it in your rear? :p
 

wbosher

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I use my stc-1000 for mashing. I've never calibrated it (probably should), but have heard of plenty of people who swear by it.
 

QldKev

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wbosher said:
I use my stc-1000 for mashing. I've never calibrated it (probably should), but have heard of plenty of people who swear by it.
I agree, best thermometer ever. You can see it from a mile away, and no standing over the pot like handheld ones (not that the OP was using a handheld version). Bonus is if you are using elec for the heating you can even dial up the desired temp and walk away.
 

wbosher

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Not that lucky, I use gas. But usually pretty close by in my man cave having a beer anyway. :)
 

Stuwort

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I use a sugar thermometer that clips on to the side of the pot and the probe angles away into the wort. Wifey doesn't even miss it (yet).
 

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