Measuring Fermentation Temperature

[popmedium]

Hey mates,

Just wondering how you guys measure fermentation temp?

I cut up a stubby cooler, tape it to the side of my fermenter and stick my temp probe in there.

I actually measured the temp of the fermenting wort the other day (well after primary, most activity had died down) and was surprised to see that although my temp probe read 19 C, the temp of the fermenting wort was 22 C! What the heck would the temp be during the night of activity!?!?!

Keen to hear your thoughts.

Joel

 

[manticle]

I have my probe attached to the cube with tape and softlon foam but I always set the stc about 2.5 degrees below intended temp for the first part to allow for heat generation and plastic insulation.

Well I did before my fridge died.

Have measured actively fermenting wort previously and usually find it's around 2-2.5 degree higher than stc reading.

 

[Ducatiboy stu]

Your probe needs to be in the wort. Tapping it to the outside gives a false reason due to

A. The plastic of the ferm acts as an insulator

B. You are also measuring the outside ambient air temp along with the temp of the plastic.

 

[indica86]

Do you do that Ducati?

 

[Ducatiboy stu]

I have, but not as a rule. Adds an element of infection ingress. Generally you will find the wort temp to be within a few degrees of ambient temp. So the cooler place the better for your ferm. I have measured peak ferment temps 4-5*c higher than ambient.

Personaly, I dont bother measuring any more. So dont loose sleep over iy

 

[elcarter]

One option is to piss of the air lock and glad wrap the top of the fermenter.

Stc 1000 probes are apparently water proof

Lost one a while back and froze a lot of beer so I'm not so sure these days.

Drop Sensor into wort for bang on temp.

This of course would need to be sterilized and what ever plastic is on the wires would be in contact with the wort.

I guess if you were that particular you'd be fermenting in stainless with a pt 100 in direct contact and broke.

 

[Rubix]

Stainless steel well in the lid of the fermenter and just drop the stc probe in. Easy to steralize and accurate.

http://shop.beerbelly.com.au/equipment/fermenting/fermentor-thermowell-9-53mm-x-400mm-stainless-steel-with-grommet.html

 

[Glot]

I just have a thermocouple sensor in each fermenter and plug them into my thermometer when I want a reading. I just sanitize them and then seal the cling wrap lid over them with insulation tape.I have the temp controller probe taped to the side of the fermenter but insulated from air temp. I set the fridge thermostat just a bit cooler than my required temp so I have a back up minimum temp.

 

[jotaigna]

I stick my probe outside the fermenter with a strap and bang in a lot of insulating foam on the other side of the probe.
The downside: 1 to 2 degrees lower than inside fermenting temperature in the first 48 hours (ale) of fermentation.
The upside: easy to do, no risks of infection and it is repeatable i.e. it is always the same so set your temp control for 1 to 2 degs lower than the desired fermentation temp for good results.

On a side note, I find that the only time that 0.5C precision is needed is when you aim for(or leaving out) certain ester characters in beer. i.e. belgians and german wheat beers.

For lagers if you ferment between 10-12C there is no (major) difference, so high precision is not that warranted
For west coast ales 17 to 19C is fine and for english ales 18-20C.
In summary, an approximate setting with rule of the thumb adjustment will produce acceptable results, without much fuss.

How to arrive to a rule of the tumb? get a couple of thermometers: one in the fermenter properly sterlisied, one in a glass of water next to the fermenter, your probe stuck to the side of the fermenter. Note the readings on all three quite often (3 hours) during active fermentation and less so (12 hours) during the final stages of attenuation.
This will give you a clear picture of the differences, and then you can sleep easy anyhow.

 

[lael]

Stainless steel well in the lid of the fermenter and just drop the stc probe in. Easy to steralize and accurate.


Rubix, I was looking at getting some of these. What is the bottom made of? Have you tested the reported temp vs putting the probe against the side of the fermenter?


http://shop.beerbelly.com.au/equipment/fermenting/fermentor-thermowell-9-53mm-x-400mm-stainless-steel-with-grommet.html

 

[verysupple]

I drilled a hole in the lid of my fermentor and put in a cable gland. The ST-1000 probe get's sanitised and goes though that straight into the wort and works brilliantly. I prefer it over a thermowell because it's cheaper and I can adjust how low it hangs for doing different sized batches.

 

[Spiesy]

It's super cheap and easy to buy a thermowell and then submerge your temp probe into the middle of the wort for an accurate reading... kind of puzzles me why people cut corners and choose to do either tape something to the side of a fermenter, or measure the temp of an inactive body of liquid elsewhere in the fermenting chamber... but, each to their own...

 

[popmedium]

Thanks mates!

So, one of three options:

1. Live with it
2. Do some experiments with fermenting wort and get an average temperature differential
3. Use a thermowell (I smell a DIY project coming on!)

thanks a bunch everyone!

 

[Ducatiboy stu]

I would say all 3

 

[Rubix]

Lael, it's all stainless mate. Haven't played around taking temps from the side vs the thermowell. Might see if i can get a bit of free time tomorrow and test it out and report back.

 

[zarniwoop]

Correct me if I'm wrong on this but doesn't the fermentation, particularly in the first few days, create heat? If so by using an offset then wouldn't the temperature be correct whilst the wort in generating heat but once the primary fermentation is over it will stop generating heat, will reach equilibrium with ambient and the temperature will now be incorrect owing to the offset?

FWIW I just tape the NTC probe to the outside of the fermenter, I don't even bother with foam. The fermenter is in a fridge and has such large thermal mass that even if the temperature that the probe measures increases a couple of degrees when I open the door in comes back down again very quickly long before the fridge can kick in and start cooling.

I should probably put a thermowell in or dangle a waterproof sensor in the wort as there will be some temperature differential especially when the wort is creating heat but I tend to rely more on the insulating capacity of the fridge to mean that the temp on the outside of the fermentor is similar to the wort temp.

BTW although you'll probably get away with dunking the STC-1000 probe in the fermenter I'm not sure it will do a lot for it's lifetime and it may even affect the accuracy of the reading if the sensor gets wet (parallel resistances etc - but I need to think about that), you'd be better off buying a waterproof sensor from ebay, I haven't used these but the specs are so close that they should work fine:

http://www.ebay.com.au/itm/5Pcs-NTC-10k-1-3470-Temperature-Temp-Sensor-Probe-Thermometer-Waterproof-/300961133754?pt=AU_B_I_Electrical_Test_Equipment&hash=item4612ae74ba

Cheers

Zarniwoop

 

[Kingy]

Stainless probe into the wort set the controller temp. Sleep well at night, never worry at work.

 

[verysupple]

BTW although you'll probably get away with dunking the STC-1000 probe in the fermenter I'm not sure it will do a lot for it's lifetime and it may even affect the accuracy of the reading if the sensor gets wet (parallel resistances etc - but I need to think about that), you'd be better off buying a waterproof sensor from ebay, I haven't used these but the specs are so close that they should work fine:

http://www.ebay.com.au/itm/5Pcs-NTC-10k-1-3470-Temperature-Temp-Sensor-Probe-Thermometer-Waterproof-/300961133754?pt=AU_B_I_Electrical_Test_Equipment&hash=item4612ae74ba

STC-1000s are sold as aquarium temp controllers....I'm pretty sure the probe is properly water proof. I also check the calibration every couple of months and it hasn't changed over the year I've had it.

 

[jaypes]

Yes, fermentation is an exothermic reaction so if you want to ferment at 18 Degrees and the yeast strain you use actually bumps this up to 20 degrees then you can adequately compensate.

Reality is that you cannot predict what this number will be due to yeast strains, health and quantity of yeast and how active the ferment is.

Saying that, I just tape a foam block over the sensor and set to 18 for my ales, pretty good drinking IMHO but YMMV

 

[breakbeer]

Extra hole drilled in the lid, probe dropped into the wort & good old gaffer tape to seal it

I prefer to measure the temp of the actual wort rather than the plastic holding it