Measuring Temperature.

[jupiter]

I've just set up a DataTaker DT50 ("borrowed" from work) to measure the temperature of my fermenter. at the moment i've just got a home-made thermocouple blu-tac'd to the side of the bucket. not accurate, but i know the best way to measure the temperature is to immerse it in the brew.

how have you guys done this?

 

[jimmy01]

Hi Jupiter

I haven't got the answer but am interested in this thread - so I thought I would give it a bump

I have seen one setup where the probe in inside a crimped off "intake" tube from inside a keg, then immersed into the fermenter thru a second hole in the lid. (Not sure what the correct name for the "intake tube" is or where you get them.) The probe & lead never comes in contact with the wort.


Cheers

 

[mika]

Jupiter, some people go to a lot of trouble with immersion tubes and all the rest, though some american brewers are of the belief that the plstic the fermentor's are made out of is thin enough to get a resonably reliable reading, as long as the probe is taped directly to the wall and insulated from the outside with a piece of foam...though I haven't conducted an experiment to verify either of these theories.

Look up the Perth Brew day being hosted by AusDB and register your interest, we're always happy to see a new face.
And welcome to the board.

Mika :beer:

 

[Ross]

Jupiter,

I made a dip tube from a spare keg diptube (got 3 out of it) - little bit of sealent up the end & crimped.
Fits in the standard airlock hole perfectly & lets you control the ferment very accurately.



Cheers Ross

 

[jupiter]

cheers guys for the replys.

i got a hold of some stainless steel tubing today to make some probes. i was planning on sticking the thermocouples down the tube and crimping it in the end of the tube in a vice. stainless has a habit of welding itself under pressure, so i'm hoping it wont leak.

on a side note, i've had the datataker running for the last 2 days now and noticed something odd/interesting.

blue is the ambient, red is fermenter1, green is fermenter2.

today (at 6pm) i bottled brew in fermenter2 and attached the thermocouple to fermenter1 so both thermocouples were attached to the same fermenter. i had assumed that the 1degC difference was due to the error of using a k-type thermocouple (+-1degC) but when attached to the same vessel, they measured the same. the 2 fermenters are of similar design and capacity only fermenter 1 is tall and thin, fermenter 2 is short and fat. the short fat one tracked the ambient temperature 1 degC lower than the tall skinny one.

no temperature control btw. some food for thought.

 

[vlbaby]

jupiter,
I have a k-type t/c controller on my fermenter and I originally was going to immerse the probe into the brew with a stainless thermowell but finally decided against it for a few reasons. Firstly I didnt want to have to sterilise another piece of equipment on brew day and fitting a probe into the top was arkward in my small fermenter fridge. But mostly the reason I didnt bother is that i found a solution that was much simpler and works just as well.

My thermocouple probe is just some compensation lead twisted at one end. All I do is get a 200mm square peice of alfoil folded up into a peice of around 50mm square with my T/C probe sandwiched in between the layers of foil. Then attach the alfoil to the side of the fermenter with some pvc tape, ensuring that the alfoil makes a firm and direct contact with the side of the fermenter.

The idea is that the aluminium has excellent heat transfer characteristics, and will conduct the fermenters temperature nicely thru to the probe. The pvc tape on the other hand is a poor conducter of heat, so this will sheild the probe against the ambient temperature.
I've been using this system for ages now and it works great. When it comes time to rack from the fermenter just 'un-stick' the probe from the side and your done.

sorry don't have a pic.


cheers


vl.

 

[BrissyBrew]

I currently use a sealed up dip tube as a thermowell, but will be releasing soon a unit that come with a large submersable ss probe.

 

[jupiter]

My thermocouple probe is just some compensation lead twisted at one end.

yeah, thats all mine are. you have to be careful doing this though, some compensation lead for k-types don't actually use the Type K (NiCr/NiAl) alloys rather Type VX (Cu/Constantan) alloy. the VX type compensation lead does not make a very good thermocouple.

i like the foil idea.

 

[ArnieW]

jupiter,
I have a k-type t/c controller on my fermenter and I originally was going to immerse the probe into the brew with a stainless thermowell but finally decided against it for a few reasons. Firstly I didnt want to have to sterilise another piece of equipment on brew day and fitting a probe into the top was arkward in my small fermenter fridge. But mostly the reason I didnt bother is that i found a solution that was much simpler and works just as well.

My thermocouple probe is just some compensation lead twisted at one end. All I do is get a 200mm square peice of alfoil folded up into a peice of around 50mm square with my T/C probe sandwiched in between the layers of foil. Then attach the alfoil to the side of the fermenter with some pvc tape, ensuring that the alfoil makes a firm and direct contact with the side of the fermenter.

The idea is that the aluminium has excellent heat transfer characteristics, and will conduct the fermenters temperature nicely thru to the probe. The pvc tape on the other hand is a poor conducter of heat, so this will sheild the probe against the ambient temperature.
I've been using this system for ages now and it works great. When it comes time to rack from the fermenter just 'un-stick' the probe from the side and your done.

sorry don't have a pic.


cheers


vl.

Good idea vl.

I do something of the same ilk, but a bit simpler although possibly not as accurate. I do 40 litre batches and have two fermenters on the go at once - I just wedge the temp probe between both containers so that there is fermenting wort almost all around it. Seems to work ok, although it might be +- 1-2 deg of error. Haven't checked it - not anal enough really.

cheers, Arnie

 

[jupiter]

for the moment, i've settled on a variation of the aluminum foil idea. instead of using aluminum foil and PVC tape, i'm using some adhesive aluminum foil tape (like use to tape air-conditioning ducting together).l

if i get around to it, i might do some investigation into what the relationship between surface temperature of the plastic fermenter is and the immersed brew temperature. that would tell us whether this method is actually accurate or not.

 

[marky_mark]

My problem with attaching the probe directly to the side or inside the fermentor is that you are allowing whatever temperature variability your thermostat has, to be translated into temperature fluctations in your wort (this is a variation of about 3-4 degrees C using a fridgemate temp controller).

The other problem is that your fridge compressor will turn on and stay on for a long period, taking ambient temperatures down to their min (around 2-4C); and then the compressor will stop once the desired wort temp is reached. This will then allow the ambient temp in the fridge to heat up to outside room temperature, creating a lot of condensation on the fermentor in the case of lagers.

The only way around these problems that I see is what I've done and that is to place the thermostat probe in the fridge so that it measures ambient air temp. Then use a second thermometer to check the actual temp of the fermenting wort and get a feel for how the what that temp will be given a certain ambient fridge air temperature as set by the thermostat. That way, with some experience you can maintain a fermentation temperature of dead on what you want without the fluctuations.

But anyone else got any thoughts...

Cheers Guys,

Mark

 

[blackbock]

Mark, I am having trouble understanding exactly what you propose here:

Then use a second thermometer to check the actual temp of the fermenting wort and get a feel for how the what that temp will be given a certain ambient fridge air temperature as set by the thermostat. That way, with some experience you can maintain a fermentation temperature of dead on what you want without the fluctuations.

Are you suggesting that we manually monitor the second thermometer, and if it's high or low, then what?
(I know you can't mean that - defeats the whole point of the thermostat!)

Could you please explain it a little better for the slower folk like myself?

 

[marky_mark]

Sorry If it wasnt clear guys.

I'm just sayin that you need to get a feel for how much heat the yeast will generate in the initial stages of the fermentation, so that you can work out how many degrees above ambient the fermentation will be on average, and set the thermostat temperature, which governs the air temperature inside the fridge, accordingly to achieve the desired temperature of the fermentation.

Cheers,

Mark

 

[hockadays]

Mark,

I use the same method as you and it's taken me a while to nail down some temp settings. For my chest freezer that fits three fermenters with one in active fermenting I set the ambient temp two deg lower then the target temp for fermenting and it seems to hold it there nicely. Once fermenting starts to slow I reduce the ambient temp to one degree lower then desired for the ferment. I also have the temp controller set with a 2.5deg of differential.

hockers

 

[jupiter]

at the end of the day, the temperature you are monitoring is dependant on what you trying to achieve. if you are trying to actively control your brewing environment, then thats what you are going to monitor and not the brew itself. i'm just trying to monitor my brew temperature (i have little-to-no control over it) so im trying to do that as accurately as possible/necessary.

i can see the temperature probe placement for the controller is a very important point. :beer:

 

[BrissyBrew]

jupiter

the temperature probe placement for the controller is a very important point.

Exactly why I had my new probes designed for my controller made so that they fit a standard airlock and are just long enough to that the tip is immersed into the wort.

I have seen a few other posts where outside air temp, air temp of the fridge and the wort have been measured and the wort at the peak of fermentation varies 5 to 10*C from the air temp of the fridge.