temp probe outside or in fermenter?

[paulyman]

Cheers Seamad, years of positive data sounds good to me. Will give it a go in the next brew.

 

[TheWiggman]

Fermentation generates heat. The glass of water won't. Fermenter also has more thermal mass than a small glass of water and is insulated by a different material. About the only thing the two have in common is that they are both volumes of liquid inside a container.

Respectfully manticle, that's the misunderstanding and the reason I asked (a little facetiously). All the above matters naught bar the fermenter generating heat if the temp of the environment is constant.
If (if) the temp of the fridge is 4°C, so will be everything in the fridge given time. The volumetric heat capacity (what's meant by thermal mass, which is a term used in building) will determine the rate at which the vessel gains or loses heat from/to the environment. Will happen much faster to the small vessel.
The material it's made of, much the same.
In a fridge, over time, a large and small vessel (not fermenting beer) will be roughly the same temp if using the small vessel's temp to control. It will cycle more often but be more tightly controlled.
If using the large vessel, the small vessel will get colder but will eventually increase to the temp of the large vessel.
Now in my case (when I posted the pic) I adjusted some settings on the STC to extend intervals and waited until it was to cut back in before checking. Then checked later again to confirm. I double-checked last night as per Spiesey's recommendation and found the wort to be a degree and a half warmer than the glass of water, and it was actively fermenting. Adjusted the STC offset to suit (disregarded glass of water), and I think it's pretty bloody accurate now until I get my dip tubes.
My post was admittedly alarmist but I'm pretty confident if you use the ol' bottle of water with probe in the fridge technique, and you know the difference between it and a fermenting beer generating heat, you're going to be accurate within a degree.

 

[michaeld16]

But isnt it just as easy to stick it on the side of the fermenter and not have to worry about working out the difference between fridge air temp and fermenting wort

 

[TheWiggman]

I just deleted my reply over-analysing things. I think I should talk less publicly and take my own advice sometimes.

Yes you are right. The biggest mistake I made was not calibrating the STC-1000 to the temp in the wort, regardless of lengthy investigation or explanations. Submersing in the liquid (beer/wort) is the only true way to know the temp though.

 

[manticle]

Respectfully manticle, that's the misunderstanding and the reason I asked (a little facetiously). All the above matters naught bar the fermenter generating heat if the temp of the environment is constant.
If (if) the temp of the fridge is 4°C, so will be everything in the fridge given time. The volumetric heat capacity (what's meant by thermal mass, which is a term used in building) will determine the rate at which the vessel gains or loses heat from/to the environment. Will happen much faster to the small vessel.
The material it's made of, much the same.
In a fridge, over time, a large and small vessel (not fermenting beer) will be roughly the same temp if using the small vessel's temp to control. It will cycle more often but be more tightly controlled.
If using the large vessel, the small vessel will get colder but will eventually increase to the temp of the large vessel.
Now in my case (when I posted the pic) I adjusted some settings on the STC to extend intervals and waited until it was to cut back in before checking. Then checked later again to confirm. I double-checked last night as per Spiesey's recommendation and found the wort to be a degree and a half warmer than the glass of water, and it was actively fermenting. Adjusted the STC offset to suit (disregarded glass of water), and I think it's pretty bloody accurate now until I get my dip tubes.
My post was admittedly alarmist but I'm pretty confident if you use the ol' bottle of water with probe in the fridge technique, and you know the difference between it and a fermenting beer generating heat, you're going to be accurate within a degree.

Over time, everything will equilibrate sure but it is the early part of fermentation where temp is key. How much time for 20 L of heat generating liquid to match 100 mL of non- heat generating liquid?

 

[Matplat]

I filled my fermenter with tap water which came out around 28deg, then set the temp on the STC to 18 and stuck the probe on the outside using blu-tack (acts both as an insulator to air temp, and a heat transfer medium from the FV). I figure this is a reasonable approximation of cooling a wort as I am cooling something that is hotter than desired temp.

When the STC got to 18deg the water temp was 2deg higher, this data point is only relevant when the temp probe first reaches it, as obviously the system would equalise over time as no heat is actually being generated by the water.... I will be setting my STC 2deg below desired temp with the probe on the outside where it doesn't need sanitising and doesn't get sticky. :beer:

 

[mosto]

I just dangle the probe so that it's up against the side of the fermenter(s). I've done a couple of basic tests and concluded that the wort will be roughly 2c higher than the air temp, so I set my STC accordingly. I often have two fermenters (20L jerry's) in the same fridge, in which case the probe is wedged between two, essentially insulated by the two batches of wort.

 

[gezzanet]

I use plastic fermenters. I Use the lid instead of glad wrap because I have a ss thermowell in the lid held in place by a airlock grommet. Probe sits in the thermowell. Works great. No liquid or grease in thermowell. I tried the thermowell with and without grease and no real difference. Grease just makes it messy when you skip it in or out. Lol

 

[mofox1]

Does said thermowell go down under liquid level? Where do you get such beasts?

 

[stux]

Does said thermowell go down under liquid level? Where do you get such beasts?

Yes.

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

 

[TheWiggman]

I got me two of them too mofox. Other option (for me) was this from craftbrewer: http://www.craftbrewer.com.au/shop/details.asp?PID=955
It was twice the price and only 200mm long, so probably not long enough through the lid if I wanted to do a 10l batch in my Coopers fermenter.

Just quietly beerbelly shipped them the afternoon I ordered them. Very happy with that.

 

[tugger]

Or in the bung hole.

 

[mofox1]

Or in the bung hole.

ImageUploadedByAussie Home Brewer1423109239.925153.jpg

lolz

 

[mosto]

Or in the bung hole.

ImageUploadedByAussie Home Brewer1423109239.925153.jpg

What are you measuring the temperature of??? :unsure:

 

[TheWiggman]

Just installed my beer belly dip tube, ruining a lid in the process.
Took it off the side of the fermenter, then stuck it in the dip tube. Dip tube was 0.3°C cooler. This is with an air circulated fridge.

 

[daveHQ]

Just installed my beer belly dip tube, ruining a lid in the process.
Took it off the side of the fermenter, then stuck it in the dip tube. Dip tube was 0.3°C cooler. This is with an air circulated fridge.

As Dr Karl would say "do the experiment"!!!!

 

[droid]

feck it, just ordered the ss thermowell

 

[Exile]

Got mine from brewershardware.com the 12" one
I found the one with the grommet in the pic above kind of loose, and it was a bastard to remove and clean.

 

[Spiesy]

Can't believe this thread is still going... or can I?

 

[Coalminer]

Other option (for me) was this from craftbrewer: http://www.craftbrewer.com.au/shop/details.asp?PID=955

These are brilliant. It fits a standard airlock grommet perfectly
Mine is set up halfway between edge of fermentor and the centre but does not seem to matter (found by experiment) as convection currents in the fermenting wort even out
the temps across the whole fermentor.
I use male/female RCA plugs from Jaycar to connect to STC1000 so easy to disconnect when removing fermentor from fridge