# A better way to tell the temperature of your fermenter



## Rod (27/3/14)

Only yesterday I had the dirts with my fermenter 

could not read the temperature with the coloured strip

used a hand held thermometer in the liquid to confirm temperature before adding yeast

those strips have a short life and are difficult to read

saw this today

http://www.kogan.com/au/buy/digital-lcd-fridge-thermometer/

$4 

worth a try with a bit of blue tac

which is what I use with my fridge mate set up


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## Spiesy (27/3/14)

Whilst there's quite a few threads dealing with this, I really don't think you'll find a better method than a temperature controller inserted into a thermowell.

Costs a little more than $4, sure - but when the average brew takes me 4-5 hours of work, a couple of weeks in waiting time and $20-30, I'd rather do it right.


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## verysupple (27/3/14)

Spiesy said:


> Whilst there's quite a few threads dealing with this, I really don't think you'll find a better method than a temperature controller inserted into a thermowell.
> 
> Costs a little more than $4, sure - but when the average brew takes me 4-5 hours of work, a couple of weeks in waiting time and $20-30, I'd rather do it right.


I totally agree. In fact, I'm not even satisfied with the cheaper options like my STC-1000. The minimum 0.3 C differential annoys me because it _forces_ overshooting. So I'm in the process of building and programming my own controller. I've got most of the components, I'm just trying to decide whether to make it PID or something custom. 

On the other hand. If all you want is a temp probe, then you can't get much cheaper than that. Although I'm not sure I see the point in a device that reads out to a precision of 0.1 C but is only accurate to 1 C. What's the point of the decimal place if you can't trust it? You're better off just not displaying it.


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## growler (27/3/14)

VS,

I think that you know yeast is able to work over a wide range of temps. Good beer was and has been brewed, long before thermometers were invented.

The desirable fermentation characteristics do not require 0.5 C temp controll. The difference betwen 17C and 35C is required.... not 17.3 and 17.4!!!

G


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## MastersBrewery (27/3/14)

I've seen graph traces from a Brew PI with 0.1F in either direction, thats like 0.05c but note BrewPI uses a complex algorithm to control ferment temp. Thermowell is a must for this sort of resolution obviously


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## verysupple (27/3/14)

growler said:


> VS,
> 
> I think that you know yeast is able to work over a wide range of temps. Good beer was and has been brewed, long before thermometers were invented.
> 
> ...


Yeah, you're right, we don't need sub-degree control. However, "Back in the day we didn't have these fangdangled temp. control systems" is a poor argument. Beer styles and expected quality have changed a great deal since the pre-thermometer days.

I was just expounding on Spiesy's sentiment that so much time and effort goes into this hobby that for the sake of a few (not too many) dollars more, you may as well do it as best you can.

And just to make it clear, I'm not expecting people to go out and buy the latest and greatest temp. control gear. I'm just building it because I saw room for improvement and I have the skills and willingness to kill invest time. Mostly because I can.


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## Cervantes (27/3/14)

I went a similar route to the OP.........

http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=131127652071

and as a check.........

http://www.ebay.com.au/itm/301096481806?var=600209301241&ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

Not sure of the accuracy as they can sometimes disagree with each other, but one things for sure. It beats trying to ferment on the laundry worktop and regulate the temperature by opening and closing the back door.

Cheers
Andy


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## verysupple (27/3/14)

Maybe we're getting a bit OT here, but anyways.



MastersBrewery said:


> I've seen graph traces from a Brew PI with 0.1F in either direction, thats like 0.05c but note BrewPI uses a complex algorithm to control ferment temp. Thermowell is a must for this sort of resolution obviously


Yeah, BrewPi is a bit more hardcore than I'm building - way more functionality and I'm only aiming for <0.15 C stability (after stabilisation time which is necessary with any feedback controlled system) for 20 - 25 L batches in a 250 L fridge. Having said that, the custom approach I mentioned sounds similar to thiers. I'm calculating the air temp in the fridge needed to achieve the desired beer temp (using 2 probes obviously). Again, because I can...hopefully.


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## Rod (28/3/14)

I may have missed my point

this was instead of the strip you glue on the outside of the fermenter

not the accuracy etc

just want to check before yeast addition and then putting into

the temperature controlled fridge which is only to one degree anyway

cheaper than the strip

getting off the original post

lets face it control between a few degrees is enough anyway


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## MastersBrewery (28/3/14)

verysupple said:


> Maybe we're getting a bit OT here, but anyways.
> 
> 
> Yeah, BrewPi is a bit more hardcore than I'm building - way more functionality and I'm only aiming for <0.15 C stability (after stabilisation time which is necessary with any feedback controlled system) for 20 - 25 L batches in a 250 L fridge. Having said that, the custom approach I mentioned sounds similar to thiers. I'm calculating the air temp in the fridge needed to achieve the desired beer temp (using 2 probes obviously). Again, because I can...hopefully.


Still OT sorry This maybe of some use to you


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## Scooby Tha Newbie (28/3/14)

http://aussiehomebrewer.com/topic/78460-temp-probe-location/#

Its been done bf mate. works a treat


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## marksy (28/3/14)

Fill a long neck up with water and stick a thermometer in it. Place it next your beer. Bang!


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## Scooby Tha Newbie (28/3/14)

marksy said:


> Fill a long neck up with water and stick a thermometer in it. Place it next your beer. Bang!


Problem with that is yeast creates heat whilst in growth ( ferment) stage. 
A bottle of water wouldn't help unless you floated it in you fermenter. 
That I dare say that would be problematic infection wise.


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## Spiesy (28/3/14)

50 years from now I predict there will still be debate on wether dried yeast should be hydrated and if monitoring temperatures outside the fermenter is the best method for temp control.


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## MastersBrewery (28/3/14)

I note one graph in the HBT thread link I posted shows a definite kick at the point fermentation has ceased producing heat, I agree that the degree of control required to achieve "the perfect ferment" is and will probably always be subjective and open to much debate. If the tools to attain finite control are available and with in your budget why not ensure your doing the best you can, it's not like your forking out $7000 for a WW


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## spog (28/3/14)

Rod said:


> Only yesterday I had the dirts with my fermenter
> 
> could not read the temperature with the coloured strip
> 
> ...


Rod, I am guessing that you don't use a temp controlled fermentation fridge/ cupboard ?.


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## Scooby Tha Newbie (28/3/14)

Shorely you jest about the hand in the liquid thing. 
I may just try that,then again I may just train my cat to do it.


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## Rod (29/3/14)

spog said:


> Rod, I am guessing that you don't use a temp controlled fermentation fridge/ cupboard ?.


I do use a temperature controlled fridge in summer and a temperature controlled heat pad sometimes in winter

this device is only to check the temperature before adding yeast

I normally check with the strip which is stuck on the side of the fermenter , but those strips do not last long and you cannot read them sometimes

better to check before you add yeast than to find it is too high before it is too late

sigh :unsure:


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## Ducatiboy stu (29/3/14)

Spiesy said:


> I predict there will still be debate on wether dried yeast should be hydrated .


 and with that....AHB explodes...


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## Rod (29/3/14)

*my original statement*

Only yesterday I had the dirts with my fermenter 

could not read the temperature with the coloured strip

used a hand held in the liquid to confirm temperature before adding yeast

those strips have a short life and are difficult to read

saw this today

http://www.kogan.com...ge-thermometer/


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## Scooby Tha Newbie (29/3/14)

Sorry Rod I thought you ment you placed your hand in the fermenter to check the temperature, not a "hand held" device. Lol to many liquid refreshments last nite.


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## Rod (29/3/14)

Would have been helpful if I included the word thermometer after hand held

:lol:

I knew what I meant


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## Scooby Tha Newbie (29/3/14)

Cool man I might still try with the cat. He needs a bath anyway. ;-)


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## marksy (29/3/14)

How much heat would the yeast create and would the heat be evenly applied to the wort? 

Can u take a Reading when checking the grav?


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## Scooby Tha Newbie (29/3/14)

Bit of a mixed bag that question. 
Simple answer is no its not even. 
In terms of home brewing it's a misnomer tho. If you where doing say 100lt or even 60 I could see it being a small issue. 
Thing is as heat rises and cold drops there is to a certain extent movement in the fermenter. Cooling provided buy say a ferment fridge will only penetrate to a certain extent. As the fermenting lquid heats (yeast activity) there will be currents created within the fermenter. 
Once equilibrium is reached (temp) its a non issue in my ipinion. 


There was talk about putting a thermo well in the fermenter to get a "core" temperature. This I feel is over kill. Just my opinion(flame suit on)
I was just tapping my probe to the side of the fermenter. Now I do this. I like it and it works for me.


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## Spiesy (30/3/14)

Lol at "overkill". It's easier than having to tape up your thermometer every time. Insert thermowell, insert probe. Done.


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## wynnum1 (30/3/14)

_Bluetooth Thermometer_


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## MastersBrewery (30/3/14)

wynnum1 said:


> _Bluetooth Thermometer_


nice toy, and I love gadgets but for ferment? I ain't getting out of bed at 2am because my brew has over shot by 3c


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## Scooby Tha Newbie (30/3/14)

Spiesy said:


> Lol at "overkill". It's easier than having to tape up your thermometer every time. Insert thermowell, insert probe. Done.


True mate. That one is a new fermenter so not shoure if you can see the other but it's semi permanent. As well that piece if neoprene is to small for my fridgemate probe. 
So normally it's place fermenter in fridge insert probe close door. Done.


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## ricardo (2/4/14)

Slightly off topic but i'm thinking of upgrading my temp controller to this. 

http://buy.ohmbrewautomations.com/

Has anybody bought one, i contacted them and they said they have shipped quite a few to Oz?


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## mb-squared (2/4/14)

Hi ricardo, if you are thinking of spending $155 on temp control, then I'd encourage you to consider the BCS-460. With that you'll be able to control up to 4 fermenters and/or the heat sources on your brew rig ... simultaneously! It would be a better investment in my mind.

2c


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## SJW (2/4/14)

I just poke a hole in the top of the glad wrap and drop the temp probe straight into the wort. 100% temp accuracy with no need for corrections or guessing.


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## gava (2/4/14)

Oh great! thanks for showing me BrewPI.... new project starting... 

-Gav


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## MastersBrewery (2/4/14)

Gav,
I do these things out of the kindness of my heart and to inspire your missus to hate me just a little 

MB


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## MastersBrewery (2/4/14)

And some further inspiration


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## panzerd18 (11/8/14)

Rod those thermometers on ebay are around $5 delivered now.


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## Diggs (17/8/14)

SJW said:


> I just poke a hole in the top of the glad wrap and drop the temp probe straight into the wort. 100% temp accuracy with no need for corrections or guessing.


As in its in there through the whole fermentation?


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## bobsantos (29/8/14)

You can atleast use stick-on thermometer. This instrument is cost-effective and accurate to results.


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## Feldon (29/8/14)

Scooby Tha Newbie said:


> Cooling provided buy say a ferment fridge will only penetrate to a certain extent.


This concept comes up time and again whenever temp control is discussed. But its so wrong.

'Cooling' does not get into the fermentor. The heat in the fermentor gets out into the air in the fridge. 

The word 'cooling' is an easy human construction we use to make sense of the world we live in. And for a lot of purposes it works OK.

(Its a bit like ignoring the curvature of the Earth when reading a road map. Just because you can navigate with a flat map does not mean the Earth is flat.)

In nature there is only heat (energy), not 'coolness'. And it will only move from places of high heat concentration to places of relatively lower heat concentration. Never the other way around.

The means of heat transfer are :
Convection - transported on liquid or air currents - eg. the wort in a fermentor or the air in a fridge;
Conduction - through a conductor - eg. through the walls of a plastic fermentor (a relatively poor conductor compared with the metal of a thermowell);
Radiation - like the sun radiates it's energy to Earth through the partial vacuum of space. Radiation is of no practical relevance to homebrew temp control (unless you leave your fermentor in sunlight!).

These basic principals are fundamental. Must get our heads around this if any conversation about temp control is going to go anywhere.


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## leighaus (30/8/14)

Well said feldon... What's your opinion best place to read the temp of your wort ?


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## Feldon (30/8/14)

leighaus said:


> ... What's your opinion best place to read the temp of your wort ?


(In the context of fermenting in a fridge I assume you mean beer, not wort. Wort becomes beer the moment you add yeast).

If you want to know what temp the beer is really fermenting at, then stick a temp probe directly in the beer, about two thirds up from the bottom where active fermentation is mostly taking place (for ale yeast anyway). This is not usually practical so a probe in a thermowell is next best.

Of course you can also attach the temp probe to the outside of the fermentor as many (most?) people do. It can work fine, but be aware that the actual ferm temp inside the vessel is probably a little bit higher during active fermentation than the indicated reading you will get. In practice, if you're making great beer with a probe on the outside keep doing it, just don't fool yourself into thinking you know what temp you are actually fermenting at - you probably don't.

You should also insulate the probe from the air in the fridge by covering it with something. You want to measure the beer temp, not the air temp. Air in the fridge is much more susceptible to wild fluctuations in temp (eg. as soon as you open the fridge door) than the beer which has a much higher thermal mass and will take much longer (hours) to shift in temp in response to being subjected to higher or lower outside air temps.

If you are using one of the new stainless bucket type fermentors or a stainless conical I would think that putting the probe on the outside would be pretty much equivalent to using a thermowell. Metal is much more conductive than plastic. And again, insulate the probe from the fridge air.


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## Adr_0 (31/8/14)

Try this:




there is a 3/8" thermowell - I think from Beerbelly? - with a Keg King controller, CO contact cleaner, a big syringe of heat transfer compound (about 25mL - get from Jaycar), epoxy, and a length of heatshrink.

The Keg King probe is 6mm OD, and the thermowell is 7mm ID so a pretty tight gap.

I just doused the inside with contact cleaner until it poured out, and some gunk came out. That's about the best I could hope for I think.

I used the heatshrink (6mm) to get heat transfer compound all the way to the bottom of the probe. I calculated that 40cm of 0.6cm heatshrink is about 11mL, so I gauged this on the syringe. Once I had hit that, it was very hard to push through so I gently lifted as I pushed, to add about 2mL to the bottom. That should be plenty.

Then, added the probe from the controller in... pushed it down to the bottom and it got nice and squishy. Sweet.

Then just filled up with epoxy with a mixing nozzle. 60min set time, good for 70°C - fine for fermenting.


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