Temperature Of Boiling Wort?

[Bribie G]

I have two digital stick thermometers - the one from CB I have been using for years that proclaimed "never needs calibrating" so I've trusted it. Last time I checked it, it read 100 in boiling water.

On moving States I mislaid it so bought a similar one from Target - then I found my original in a box with my regs and taps and lube and stuff.

I've just tested both of them in boiling wort (around 1039 at beginning of boil)

Old faithful reads 106, the new one reads 100

I know that wort boils a bit hotter than water but there seems to be a serious problem looming here - the Target one is obviously under reading, but how's old faithful doing?? anyone have the answer for wort? <_<

 

[Phoney]

I doubt it's going to boil anymore than half a degree hotter than 100C with that small amount of sugaz in the mix.


The saying goes; Ask a man with a thermometer what the temperature is, and he'll tell you. As a man with two thermometers, and he'll have NFI. There was a link posted on here a while ago to glass lab grade thermometers that were ridiculously cheap, like $1.70ea. Buy a few of them and use it to calibrate your digi's.

 

[Bribie G]

I think I need to seriously renew my thermometer stock. A few brews ago I fished out my old glass thermo from a few years ago and it was six degrees out :huh:
I mean what's the point of going for a precise stepped mash if the thermometers are unreliable.

Edit: and if the mash is at the wrong temp the refractometer isn't going to pick that up because your gravity is your gravity, but an unreliable thermo means that there are the wrong sugaz constituting that gravity. So Old Faithful, if over reading, is making me mash at say 62 instead of 67 which is fecking serious.

 

[QldKev]

I've got an alco filled calibration thermometer that I set all my stc-1000's from. I'm hoping to brew tomorrow, I'll chuck it in the boiling wort and let you know what it reads. The only thing I'm thinking is will it matter how hard the boil is? A roaring boil jumping out the sides of the pot mush be hotter than a mild rolling boil?

QldKev

 

[Bribie G]

Kev, where did you get your alco thermometer from? I really should get one. There seem to be any number of digital probe stick types on the market but no guarantee that they would be anything better than what I've got.

 

[GuyQLD]

I've got an alco filled calibration thermometer that I set all my stc-1000's from. I'm hoping to brew tomorrow, I'll chuck it in the boiling wort and let you know what it reads. The only thing I'm thinking is will it matter how hard the boil is? A roaring boil jumping out the sides of the pot mush be hotter than a mild rolling boil?

QldKev

No, it's not.

It's merely a case of how quickly bubbles of steam are forming due to the higher heat from the source. Pure water boils at 100'C always. A strong boil (and subsequent more boil off) is purely because the higher amount of heat going produces more steam, more steam has to escape, it forms the "rolling" boil we all love. Temp is still 100'C though.

edit: Although wort would be a touch higher, I can't see it being much though.

 

[labels]

The trouble with calibrating thermometers at 100C is they may be accurate at 100C but not accurate within the temperature range you're using them at - mash temperatures for example.

In my opinion thermometers should be calibrated within at the temperature range you normally use them for and if you're using thermometers at different extremes, have multiple thermometers.

Steve

 

[QldKev]

The trouble with calibrating thermometers at 100C is they may be accurate at 100C but not accurate within the temperature range you're using them at - mash temperatures for example.

In my opinion thermometers should be calibrated within at the temperature range you normally use them for and if you're using thermometers at different extremes, have multiple thermometers.

Steve

I calibrate mine at 66c.
But in Bribie's case it's a bit far for him to check his against mine. So we are trying to use the boiling point as a temporary guide.

 

[QldKev]

Kev, where did you get your alco thermometer from? I really should get one. There seem to be any number of digital probe stick types on the market but no guarantee that they would be anything better than what I've got.

I got mine from ebay a long time back.

It's a bit like this one but has a stainless back on it. I just checked it and it only goes to 105c.

edit:
From here, looks like we should aim for 102c

QldKev

 

[rotten]

Are you telling me I need to have two thermometers then. One for mash and one for nearing boil? I was sure a cheapo liquid jobbie would be right for both??

 

[dr K]

Pure water boils at 100'C always.

I guess you are sea along with the rest. (no mash intended)
Oh FFS I won't mention barometers ....
K

 

[Fish13]

I guess you are sea along with the rest. (no mash intended)
Oh FFS I won't mention barometers ....
K

yeah that pressure measuring device. lol

 

[Brewman_]

I never thought of the boil temp being critical, it is a the temperature at which the wort boils, it does not matter because it won't change unless you change the pressure of the vessel. It's not like you can dial into you gear to boil at a low temperature of 5 degrees under BP, then it ain't a boil. Unless you can provide a vacuum, then it is possibe. Must get the old vacuum plumbed into the kettle, why didn't I think of that earlier?

Fear.

 

[Nick JD]

Pure water boils at 100'C always.

I've seen pure water boiling at 20C.

 

[DJR]

Just tested my rolling boil wort (about 1035-40 SG) - 99C

Mind you I am at 670m above sea level

 

[Hippy]

I've seen pure water boiling at 20C.

unless you were looking at it through some kind of glass panel you must have been out of breath

 

[Brewman_]

Is a bubbling Bong classed as a rolling boil?

 

[Hippy]

Is a bubbling Bong classed as a rolling boil?

Depends. Can be a much more vigorous boil if you have decent set of lungs.

 

[Thirsty Boy]

wort in a big arsed (i mean really big) kettle at about 1.060 - is boiling at about 102-103

so if your measuring 1.040 wort in a homebrew kettle at 106 - your thermometer is out no doubt about it.

Calibrate at several diffent temps

Vigorously boiling water (at around sea level) - 100
2/3rds ice 1/3 water stirred continuously whilst taking the temp - 0
Up your bottom or similar body temperature location - 37 (unless you aren't feeling so well)

Thats 3 "known" temperatures you can test your thermometer against and get a feel for where it sits across the range. Sure, none of them are mash temp.... but nothing much is that you can test against unless you have access to a handy lab

 

[GuyQLD]

I guess you are sea along with the rest. (no mash intended)
Oh FFS I won't mention barometers ....
K

I suppose I deserve that for throwing absolutes around. My point was more that the stronger boil has no affect on the temperature. I didn't expect people to start talking about brewing on Everest or in a vacuum.