Temperature Data Logging Experiment.

[Superoo]

Howdy All,

I am in the process of fitting an 8 channel temperature data logger to my fermenting fridge.
Each channel is accurate to 0.1 deg c, and it can take 1 minute samples of all 8 channels for basically years.

Its initial purpose is to try and work out where is the best place in my fridge to locate the sensor of my temp controller, to be able to acheive the smoothest temp control, and maximum power efficiency.
I have never been sure if the sensor is best located in the air, at the fermenter top, middle or bottom ?
The temp varies from top to bottom of the fermenter and the fridge, so now I can find out by just how much, and if it can be improved on.

I will also be using the logger to see what advantage (if any) there is to using a pc fan for air circulation in the fermenter fridge, other than the advantage of no mould when you use a fan.

I am just posting here to say if theres anyone out there that would like me to do any temp related brew experiments with this logger, just post here and I'll happily do whatever you wish on my system, and email you a chart in excel with the results.

I will later be adding some relay control to it, to use as a programmable temp controller for BIAB in a 40Lt Urn, plus as a normal fridge / freezer temp controller, but one thats really dedicated to home brewing, to control a fermeting fridge and a keg fridge simulateously.

It might be interesting to see what temp fluctuations there are with and without the pc fan, and depending on where the controller sensor is located, might be able to save on power costs.
Also I will check what happens when the bottom of the fermenter sits on a piece of foam to insulate it from the freezer floor.

The other factor which could save power is allowing for the outside air temp, in the timing of how long the freezer runs while cooling, reducing temperature undershooting, and again saving power.

So if you are curious about anything related to this stuff, please let me know.

Cheers,
chris

 

[Andyd]

Everyone I've spoken to about this says don't put it in the air - put it in the liquid instead (via a thermowell). Or, if that's not possible, tape it to the fermentor and put some insulation around the outside of the probe so that you're reading the temperature of the liquid.

Personally I watch both temperatures. Yes, I'm fundamentally interested in the temperature of the fermenting liquor, but that doesn't mean I want the environment in the fridge running off to extremes (which could happen, given the thermal mass of the liquor).

As an example, when I first started brewing it was the middle of winter, so there's a heating element in the fridge to push the temp up to what I was hping would be a comfy 19 degrees. I just had the probe in the vessel, and was somewhat disturbed when I openned the fridge to find that the interior was running at 50 degrees C!

So, in short, since you're looking for the contained environment to come to a thermal equilibrium, having the probe in the air works for me. And having a second probe on the vessel just gives me some extra comfort that things are going well in the fermenter.

Of course, extreme temperatures will speed things up a little in achieving that equilibrium, but may have detrimental effects on your flavor profile (since the boundary regions will experience sub-optimal temperatures...)

I'm just going to sit back now and let the wave of disagreement wash over me

Andy

 

[michael_aussie]

I'll have to think about any special requests ....
either way .. I'd be interested to see your results and where you had the probe, how you were controlling etc....
good luck.


I wish I had one....

 

[Tony]

i put a PT100 probe through a 16mm cable gland in the fermenter lid and have it sitting in the liquid. I use this to control the fridge and keep my ferment within + or - 0.2 deg.

Will post some pics up later if i remember, gotta go get a haircut now

cheers

 

[Superoo]

@ Andy...
You seem to have a pretty good grip on temp related stuff, your post makes lots of sense.
Please keep an eye on whatever happens here, and please feel free to jump in and correct / suggest anything along the way.
I had actually thought about insulating the sensors on the outside of the fermenter as you mentioned.
And yes, having the probe in the air seems the best approach, so doing this should just give a little bit more insight into exactly what happens thru the whole fridge / fermenter.

@ Michael...
Will certainly be posting some results of pc fan locations etc.
I also at the moment am using a 1 deg resolution controller, which results in a large temp swing, so thats part of the reason for making my own with 0.1 deg resolution. (Using 8 of DS18B20 sensors).

@ Tony...
I'll be fitting one of my probes thru the lid using a gland as well, have to resin one of the sensors into some SS tube first.
Am also hoping to get the temperature swing down to within 0.5 deg c, rather than 1.5 to 2 degrees it is at the moment.


Will start logging some stuff hopefully during the week (and learning to do basic charts in excel).

Cheers Lads...

 

[speedie]

you boys are going to kill that fridge motor with a .2 split on the differential
reasoning is it doesnt have enough off cycle!

 

[Tony]

50 liters here mate...... takes an hour or more to change up and cycle back on

and it cost me $50.... been using it for 7 years

Who cares

cheers

 

[schooey]

..gotta go get a haircut now

shouldn't take long...

 

[michael_aussie]

I am just posting here to say if theres anyone out there that would like me to do any temp related brew experiments with this logger, just post here and I'll happily do whatever you wish on my system, and email you a chart in excel with the results.

I'd be interested to see the following comparisons.

TEMP PROBE LOCATIONS.
A. On the side of the fermenter with foam or something similiar, insulating from the surrounding air.
B. In a thermo-well or similiar to get the "core temperature" of the brew.
C. Sitting on the lid of the fermenter (I coil mine around my air lock).
D. In the "free air" of the ermenting fridge away from the fermenter.

Control on each of the locations, one at a time, for at least a full "cycle" of the fridge, and see all the traces of the four probes.

Repeat the same with the fan running.

 

[Superoo]

I'd be interested to see the following comparisons.

TEMP PROBE LOCATIONS.
A. On the side of the fermenter with foam or something similiar, insulating from the surrounding air.
B. In a thermo-well or similiar to get the "core temperature" of the brew.
C. Sitting on the lid of the fermenter (I coil mine around my air lock).
D. In the "free air" of the ermenting fridge away from the fermenter.

Control on each of the locations, one at a time, for at least a full "cycle" of the fridge, and see all the traces of the four probes.

Repeat the same with the fan running.

I'll do that no worries, but first just going to add some relay control, and the logger will also record the fridge on / off time, so that I can try to reduce temp undershoot / overshoot.
Also gotta try and source a nylon or stainless 200mm deep thermowell to place in the middle of the fermenter.

Already have the logger software recording 4 temp sensors, and have added recording of status of 8 control relays, at 1 minute intervals, so just need to add the relay control, might try and knock a proto up tonight.
See in the relay turn on / off times will show how much time the fridge runs before it has an affect, and also show the overshoot after the motor stops. Will be intersting.

Give me a week or so and will hopefully have something basic happening...

Cheers,
Chris

 

[Superoo]

Well, I fitted a solid state relay to the prototype unit last night, and overnight logged the data in the file attached.
This is just a sample, I will get a thermowell and then do some more complete tests.
It has no pc fan, and the target temp is 19 degrees c. This is my first program run, and I can probably fine tune the accuracy a bit, but its not too bad anyway, only a 0.6 degree swing, with 0.4 degree overshoot. Hysterisys is 0.2 deg c (19.0 to 19.2 deg c).
The freezer turned on twice, once for 4 mins and once for 5 mins.
As you can see it got quite cold overnight, and having no pc fan the temp started to drop off slightly right at the end.
The samples are taken at 1 minute intervals.

Tests to do...
1 - Affect of having no PC fan in your fermenter fridge.
2 - Affect of using a PC fan inside your fermeter fridge.
3 - Affect of insulating the bottom of your fermenter from the metal floor of your fridge / freezer.
4 - Affect of having your control temp sensor attached to the side of your fermenter.
5- Affect of having your control temp sensor in the air near your fermenter.
6- Affect of adding a deadband into the software of say 0.5 degrees, where no cooling / heating is required when the outside air temp is within 0.25 degrees of the target temp.

Eventually, I might make available for sale some nice home brewer specific 2 channel temp controllers, with 4 temp inputs, and optional data logging to SD memory card, so that you can log your own mash temp and fermentation.
The temperature log files open automatically in excel straight off the SD memory card.

I am intending on making a full temp controller for a 40L Electric Urn to fully control a BIAB mash (with step mash capability), and then do the full boil, including beep reminders for hop additions etc.
Like a lower cost version of the nice German ones available, without the pump, and using normal BIAB, no centre tube etc, just a false bottom to keep the bag off of the elements / bottom of the urn.

Cheers,
Chris

View attachment BREWDATA.pdf

 

[fraser_john]

Why not just mount it in a 3 liter milk jug full of acidified water (stop things growing in it). The water should balance out the effect of the heating/cooling cycle inside the fridge and once set up at the back of the fridge, you never have to mess with it again.

 

[hotchilli]

That's very cool. I've often wished I had access to a data logger so I could see what was going on inside the ferment fridge!

I've got my fermenter sitting on a 10mm thick nylon board, and I've put the temperature probe under the fermenter so it's sandwiched between the fermenter and the nylon. While it's a bit rough, it minimises the local effects of the ambient temperature inside the fridge. Given the nylon is 10mm thick, and the fermenter wall is only 3mm thick, the temperature gradient between the fermenter and probe is a lot less steep than the probe and the nylon, meaning the probe will respond to wort temperature variations quicker than ambient temperature variations. Essentially, the nylon is acting as an "insulator".

Using an IR thermometer, I've noticed theres up-to a couple of degrees variation between the top and the bottom of the fermenter. Ideally, I'd love to have a high and a low thermowell measuring both temps. I'm guessing the higher bottom temp is due to the bottom fermentation which is releasing heat while the yeast do their thing (another reason why I've got my probe under the fermenter).

Eventually, I might make available for sale some nice home brewer specific 2 channel temp controllers, with 4 temp inputs, and optional data logging to SD memory card, so that you can log your own mash temp and fermentation.
The temperature log files open automatically in excel straight off the SD memory card.

I'm keen. What's the likely cost?

 

[QldKev]

Can you add 1 more test to the set, as I would be intrested in seeing the results. I use 4b.

4a - Affect of having your control temp sensor attached to the side of your fermenter. (and insulated)
4b - Affect of having your control temp sensor attached to the side of your fermenter. (and not insulated)

 

[Superoo]

@fraser_john...
Do you mean put the control sensor in a water bottle ?
If yes, then thats another experiment to add to the list
I am trying to work out what affect these sort of things have on..
A- The actual temperature inside the fermenter.
B- The amount of time the fridge is turned on (hard to do as outside tempo never stable enough).
C- The amount of overshoot when cooling / warming.
D- The amount of actual hysterisys (overshoot + undershoot).


@hotchilli...
That will be another experiment then, actually place the control sensor under the fermenter.
This would be affected greatly by having / not having insulation under the fermenter.
I think the logical approach is to have the surronding air at the correct temp, but we will see soon.


@QldKev...
Yep, no worries, will do both.


New test list is...
1a - Affect of having no PC fan in your fermenter fridge.
1b - Affect of using a PC fan inside your fermeter fridge.
2 - Affect of insulating the bottom of your fermenter from the metal floor of your fridge / freezer.
2a - 2 with control sensor in air.
2b - 2 with control sensor at bottom of fermenter between fermenter and insulation.
2c - 2 with control sensor at middle of fermenter.
3a - Affect of having your control temp sensor attached uninsulated to the side of your fermenter.
3b - Affect of having your control temp sensor attached side of your fermenter, insulated on the air side.
4- Affect of having your control temp sensor in the air near your fermenter.
5- Affect of adding a deadband into the software of say 0.6 degrees, where no cooling / heating is required when the outside air temp is within + or - 0.3 degrees of the target temp.
6 - Affect uf using a small, say 3 Litre water bottle and thermowell for the control sensor (this would be interesting because of the different mass of the water bottle and the fermenter).

Also thinking of trying out a few of the available temp controllers and doing some basic performance tests maybe ?
If its not too politically incorrect.

Cheers,
Chris

 

[Dave70]

I am just posting here to say if theres anyone out there that would like me to do any temp related brew experiments with this logger, just post here and I'll happily do whatever you wish on my system, and email you a chart in excel with the results.

OK, you can do this for me if you like.

Plonk the data logger in the center of the wort if you can.

Then drop the probe from the fridge mate in a 2L bottle of water in the fridge and set the temp for the appropriate brew.

Then lets see how much variation there is between the set temp and actual wort temp.

My last batch of Munich helles seemed to have a few extra flavors I cant explain..

 

[Superoo]

Hi Dave,
I'll have to wait until I can get hold of a FridgeMate before I can do that, if you wanted to, you could post me yours and I would do the test and post it back asap.
Or if anyone has one laying around ????

I have ordered a thermowell, but for now I might just fold a piece of 3/8 food grade hose in half, and drop that in the wort.

I thinks its worth trying out a few of those type controllers to see not so much how accurate they are, because you can find this out yourself and allow for it, but more of how much variation / overshoot there might be.
If a controller only has a 1.0 degree resolution, then the temperature swing will be larger.

The main positive thing I see is that doing these experiments can hopefully assist people in getting the best performance out of whatever controller they are using, just through knowing the best location of the sensor and things like using a pc fan, insulation under the fermenter etc (if they prove to be a benefit).

best thing about all this - I have to keep brewing to get the tests done


Cheers,
Chris

 

[Superoo]

Been thinking, time to get some structure here...

The best order to do these tests would be to first just decide where the control temp sensor is best located for the smoothest control with the least undershoot when its cooling.
I will predict that having the sensor in the air will be the best place, as the air changes temp faster, and then transfers cooling to the fermenter.
I also think this will be improved by having insulation under the fermenter, and a pc fan, but we'll check that later.

After the best sensor location has been found, then things like insulation and PC fan etc can be compared with the control sensor in the same place each time.

These tests will run for around 24 hours of recording each.

Tonight I will log test (1a)...

Test 1 - To find the best location for the control temp sensor.
- Temperature outside, ambient (air ) in fermenter, Ferm Top and Ferm bottom monitored.
- Control on / off monitored.
1a - Control sensor in ambient air inside freezer.
1b - Control sensor on top of fermeter lid.
1c - Control sensor on side 1/2 way up fermenter.
1d - Control sensor on side near bottom of fermenter.
1e - Control sensor in middle of wort in fermenter.
1f - Control sensor in a separate 3L water bottle, insulated from floor.
... And now with a PC fan running full time...
1g - Control sensor in ambient air inside freezer.
1h - Control sensor on top of fermeter lid.
1i - Control sensor on side 1/2 way up fermenter.
1j - Control sensor on side near bottom of fermenter.
1k - Control sensor in middle of wort in fermenter.
1l - Control sensor in a separate 3L water bottle, insulated from floor.


Now using and knowing the best location for the control sensor,
and running a pc fan if that proved to be beneficial...

Test 2 - To find the affect of insulation under the fermenter.
2a - No insulation between bottom of fermenter and freezer floor.
2b - 1" foam insulation under fermenter.

Test 3 - Affect of having insulation on temperature sensors attached
to the surface of fermenters.
3a - 2 sensors alongside each other, 1 with insulation covering the air side.


Cheers,
chris

 

[matr]

Looks like I've got some analysis to do!

Email the data through when you have it.

 

[Ducatiboy stu]

In true AHB style

You know it makes sense