Temperature Measurement

[troopa]

But theres no excitement in brewing unless you replace your broken glass/liquid thermometer and noticed as you get to boiling the wort is sitting at 97deg :huh:

Tom

 

[dpnicol]

I use a glass stick with a stainless sheath because when my dial was found to be wonky I called the local micro and they use the glass stick with a stainless sheath. Not sure what their barrel capacity is but they are not the big boy in the next town that is the number 13 craft brewer in the USA. I am sure it would be hard for Deschutes to use a stick thermometer in their big brewhouse/factory but I bet they have stick lab thermometers in the lab for test work. But most micros do not have full labs and quality control chemists. I have also found that not all micros take a scientific approach to brewing. One reason why a beer will be great one batch and the next time you go to the pub it is not as memorable. Some of them are always fooling around with the recipe, and not in a good way. I am sure some home brewers have better process control then the average micro uses.

One thing I like about my glass thermometer is I never have to give it a flick to see if it is reading correct. Also every time I have checked it it is spot one. Maybe that is why they do not have to put little screws on the back to adjust it all the time.

Here, here, says the "Instro"

 

[WarmBeer]

Have recently been brewing with one of these (they're within SWMBO's brewing budget, OK!)

I decided to calibrate it side by side with my glass thermometer, and the digital one was approx 4 degrees higher at mash temperature.

I have foolishly thrown away the instructions (yes, yes, I'm in I.T. Reading manuals is indicative of weakness)

So, does anybody know any way to adjust these digital thermometers to a more correct temperature reading?

 

[glaab]

I have a similar one, theres nothing about calibrating it in the instructions. it is guaranteed to be within 1% though. can you return it? just out of interest, have your beers been turning out heavy?

 

[WarmBeer]

I have a similar one, theres nothing about calibrating it in the instructions. it is guaranteed to be within 1% though. can you return it? just out of interest, have your beers been turning out heavy?

Have only done 2 AG brews so far, and one of them was with the 4 degrees calibration in mind. Will be taste-testing the first brew tonight (maybe) so no subjective assessments yet.

FG was a little high (1012 IIRC), so the wort may have been a little more dextrinous (I believe this is what mashing high will lead to)

 

[WarmBeer]

Just an update on the calibration of the Jaycar digital probe thermometers, for anybody who is interested.

Zero calibration in a glass of ice/water slurry:
- Glass thermometer : 0 deg C
- Probe thermometer : 1.5 deg C

High level calibration in recently boiled water:
- Glass thermometer : 92 deg C
- Probe thermometer : 96.2 deg C

I probably should have performed a calibration in actively boiling water, but by that stage the beers were starting to kick in, and didn't want to mix boiling water and drunk brewers.

My conclusion is that at mash temperature, the Jaycar digital probe thermometer is reading approximately 3.5 degrees too high. I will need to mentally adjust my measurements in future, as the device doesn't appear to have any ability to calibrate the readout.

 

[warra48]

I have just installed a MashMaster dial thermometer on my HLT.
I checked it against a digital probe thermometer I use in my mashtun, and also a glass alcohol thermometer, and made a small adjustment.
All 3 are now inside 1C difference at ambient temperature.
I can live with that small a variance.

 

[manticle]

Despite having calibrated my dial thermometer with two glass stick thermometers several times, (and it reads the same when the tun is full of water) I find I get a massive difference between the dial and my glass stick in the mash.

I've concluded that the glass dial is possibly the most useless bit of kit I've bought so far. I was so proud of myself mounting it on the outside after supposedly having winged my way through many successful brews without it.

It's simply not an accurate reflection of what's going on within and needs to be ignored for brewing sanity.

 

[Greg Lawrence]

Despite having calibrated my dial thermometer with two glass stick thermometers several times, (and it reads the same when the tun is full of water) I find I get a massive difference between the dial and my glass stick in the mash.

I've concluded that the glass dial is possibly the most useless bit of kit I've bought so far. I was so proud of myself mounting it on the outside after supposedly having winged my way through many successful brews without it.

It's simply not an accurate reflection of what's going on within and needs to be ignored for brewing sanity.

Can you please tell us the brand of your glass dial thermometer.
Im looking at buying one, but dont want to be stuck with a dud.

Gregor

 

[manticle]

I'm not sure it's the thermometer to blame to be honest. As I said - if the tun is full of water then the glass inside and thermometer outside measure the same. I've calibrated them several times.

My understanding (and someone experienced like Screwtop might be able to confirm or correct me) is firstly that the probe will draw out a little heat and secondly the mash itself will never be a consistent temperature. The bottom of the mash will be insulated by the rest of the mash while the top will shed some heat. The centre will differ from the edges (confirmed by my glass stick thermometer too). The dial will only give an indication and really only from one area. I think it might be a slightly flawed concept but I'm more than happy for someone to tell me I'm using it wrong..

 

[cubbie]

I have tried a couple of digital probes and now have a glass thermo. After playing with these I have to say I am most comfortable with the glass thermo. Whilst some probes are +/- 2c other +/-1c etc, your mash itself can be +/-4c from top to bottom. I noticed this especially on the weekend when I did a two step mash the first step being fairly thick, meaning my glass thermo could touch the bottom of the mash tun, from the bottom to the top there was a large temp range.

So I would say use what you have and get a good feel for your system and a repeatable method for taking your temps, then you might want to play around with more accurate equipment.


At what depth should you take a temp....?

 

[gjhansford]

Despite having calibrated my dial thermometer with two glass stick thermometers several times, (and it reads the same when the tun is full of water) I find I get a massive difference between the dial and my glass stick in the mash.

I've concluded that the glass dial is possibly the most useless bit of kit I've bought so far. I was so proud of myself mounting it on the outside after supposedly having winged my way through many successful brews without it.

It's simply not an accurate reflection of what's going on within and needs to be ignored for brewing sanity.

I'm with you Manticle ... can't seem to get the dial to make any sense ... so I'm using the glass stick now. I'm starting to think the dial is just for show ... when the punters come over for a beer they see the 'hi-tech' dial and think I'm professional ... and I know what I'm doing ... :huh: .

ghhb :icon_cheers:

 

[Greg Lawrence]

On my glass stick, there is a line about 70mm from the bottom. i thought that this line indicated how far you should be inserting your thermometer to get a true reading.
Last mash I noticed that if i sat my thermometer on the bottom of the mashtun, it was 65 degrees, but if I held it closer to the middle of the mash (at the above mentioned line) i got 64 degrees.
Heat rises doesnt it? So why would the bottom be hotter?
My theory is that if you have too much of the thermometer in the mash, the mercury up the length of the thermometer (not just the bulb)
is expanding, giving a false reading.

Can anyone confirm what this line is for? - Sorry, my camera battery is flat.

Gregor

 

[cubbie]

On my glass stick, there is a line about 70mm from the bottom. i thought that this line indicated how far you should be inserting your thermometer to get a true reading.
Last mash I noticed that if i sat my thermometer on the bottom of the mashtun, it was 65 degrees, but if I held it closer to the middle of the mash (at the above mentioned line) i got 64 degrees.
Heat rises doesnt it? So why would the bottom be hotter?
My theory is that if you have too much of the thermometer in the mash, the mercury up the length of the thermometer (not just the bulb)
is expanding, giving a false reading.

Can anyone confirm what this line is for? - Sorry, my camera battery is flat.

Gregor

Check out post 8 in this thread.

http://www.aussiehomebrewer.com/forum//ind...st&p=564466

 

[Greg Lawrence]

Note to self: Read whole thread before posting.

 

[glaab]

... when the punters come over for a beer they see the 'hi-tech' dial and think I'm professional ... and I know what I'm doing ... :huh: .

ghhb :icon_cheers:

one peanut here come out with...
" wow, that big esky's even got a speedo on it! "

 

[manticle]

My esky was done for speeding once. Thank Christ they didn't breath test it.