Fermenting fridge - questions

[Robbo100]

Hi all.

I am thinking of adapting my HLT/Boiler Raspberry Pi Controller to control and data-log a fermenting fridge. In order that I can do this, I have a couple of questions that I hope you can help with:

1) Do people typically measure the fridge air temperature and control to this parameter, it do you measure the wort temperature using a bulkhead?

2) Typically, if you were doing a complex fermentation with temperature variation, how long would this last (in days).

3) Over what time period would you vary fermenting temperature over during this period? Would you want temperature variations on an hourly basis (e.g. 3 hours at 10 deg, 6 hours at 15 deg then 5 hours at 10 deg), or do you make variations over longer periods (e.g. days)?

Thanks

Robbo100

 

[dx4100]

1, I use water in a jar in the fridge. Then I place temp sensor in that. Gave me the best results. I tried fixing to side of FV using bubble wrap but these didn't seem as successful and was a bit of a pain. I wouldn't but it straight in the wort due to risk of infection but some people do do this.

2, Depends totally on the recipe....

3, Again, depends on the recipe....

 

[Robbo100]

Thanks

Regarding number 2, what do you think the worst case would be?

Regarding 3, do some beers really need to have fermenting changes on an hour by hour basis?

 

[Dave1970]

There's no way you could control the temp of fermentation in a fridge on a few hourly basis, it just takes too long for the temp of a large volume of fermenting wort to change. Doing a beer like Aleman's Erdinger that calls for a rising temp for the first few days I'm looking at about a degree a day increase

 

[Robbo100]

Perfect, thanks.

 

[rpt]

I stick my probe to the side of my plastic FV and cover with bubble wrap. Appears to work fine - the temperature is pretty stable. If the probe is just in the air then the temperature always overshoots and so it cycles between heating and cooling. Opening the door also affects it badly.

 

[obeytheg1ant]

I stick my probe to the side of my plastic FV and cover with bubble wrap. Appears to work fine - the temperature is pretty stable. If the probe is just in the air then the temperature always overshoots and so it cycles between heating and cooling. Opening the door also affects it badly.

The OP had nailed down the question I have been wanting to know about controlling temps in ferm-chambers, as I too recently acquired one. Air or Wort, and best method(s).
Excellent information on the probe to the FV with bubble wrap, is bubble wrap one of the cheapest or best solutions?

 

[Robbo100]

Thanks for all your replies.

I was thinking about this on the drive home (as you do…). I suspect that recording both fridge air temperature AND wort temperature would give the best results. This would allow me to write a control law whereby when there is a large difference between the measured wort temperature and the target wort temperature, then I can command a similarly large opposite fridge air temperature differential to speed up temperature correction. Then, as the measured wort temperature approaches the target wort temperature, I can reduce the air temperature differential to bring the wort temperature to the target temperature asymptoticly (if that makes sense).

Thanks for the tip about sticking the temperature sensor to the side of the FV and covering with insulations. Being anal about these things, I am still keen on measuring the wort temperature at the centre of the FV (or maybe even at a couple of places and calculating an average). I was thinking of using a DIY bulkhead like this:

.

Assuming the welds are good and there is no holes to store bacteria, do you think this might be OK (assuming a thorough use of strong bleach for sanitising)?

Am I going to OTT with this? Mind you, the fact that I am planning on getting the device to automatically generate a webpage for temperature monitoring, probably proves that I am definitely going OTT.

 

[Cononthebarber]

I leave my temp probe to stand in steriliser when I start brewing and rinse it before pitching the wort and just put it straight in the FV. Don't forget that the yeast activity creates heat as well so even a reading of the outside of the FV will not be as accurate or reflect the actual wort temperature.

 

[Robbo100]

So if the wort heats up because of fermentation, does the master brewer get their fridge to bring this temperature down to target a completely perfect constant temperature?

I have the technical know-how, but don't know what I am trying to actually achieve :-)

 

[Cononthebarber]

Yes that's what I aim for, a constant wort temperature (or as close as I can achieve) throughout fermentation. After reading the Yeast book it talks a lot about temperature fluctuations and the affect this has with off flavours, that’s what you want to avoid :thumb:

 

[nobyipa]

did an experiment a couple o months ago that answers the question about my set up
here goes

my ambient temperature is set to 20.4C
with A 0.3C tolerance
fact my wort is 19.8C
did this when took out my furstey ferret clone thingy into secondary to dry hop it
aiming for 20c
so thats my fridge TOTALLY calibrated
used me Comark thermometer to verify this

done this by taping polystyrene onto the fermenter and the sensor OR IF YOUR AMERICAN SWENSOUIR tucked inside it

:thumb:

 

[obeytheg1ant]

Any census on the thermowell stoppers?

 

[Robbo100]

I have been thinking about the best way to get an accurate wort temperature without cutting a home in the FV.

I have concluded that I will probably use some thermal paste (used to connect heat sinks to computer chips) between the sensor and the FV, then blob a load of hot glue around the sensor to attach it,
Followed by adding some polystyrene over the top as insulation.

I think this will be quite a neat and effective solution.

So, I am planning the following functions with the controller:

- System will boot-up and detect if it is connected to the HLT/Boiler or the FV Fridge

- If connected to the fridge it will display the fermentation duration on the screen, and the user can change the number of days to whatever that want.

- The system will then cycle through each day in turn (up to the number selected earlier) and ask the user what temperature they wish to target.

- When completed, the system will start.

- The brew temperature profile will be stored in a data file, so if there is an interruption in power, the system (on the next boot-up, will continue from where it left off (and display a message saying that the device had experienced a power loss).

- The system will data log "air temp" "wort temp" and fridge and heater status at 10 min intervals and display the results on a website viewable on your home network (or even Internet if you wish).

Any thoughts, ideas or advice?

 

[pogierob]

Don't over think the temp.
Ambient temperature will always give you a great result unless you open the "fridge too often". This will kick the cooling or heating elements in more often than needed.

Relax, set the temp and walk away until you believe fermentation is complete.
Roughly speaking the yeast will be happier at a constant temp and unless you are planning on going pro. Close enough to make awesome beer. IMHO

 

[Robbo100]

Thanks for the advice.

I think that most of my brews will have a constant temperature, but if I am going to the lengths of writing a computer program to do the temperature control, I figure I should go the whole hog and make something suitable for lagering while I am at it (for little additional effort).

 

[rpt]

I just use an STC-1000 to control my fermentation temperature. It's not difficult to change the temperature manually and as this doesn't have to be done very often I don't see any need to automate it. Plus, I don't start lagering or crash cooling until I have checked the gravity and am happy fermentation has finished.

I also have an unused Raspberry Pi and the skills to program it, so I might one day do something like this just because I can.

 

[Robbo100]

I think your last statement just about covers it. :-)

I wanted to make something with the Pi to teach myself some coding, and having a project you care about is the best way to get the motivation to learn.

Having made my boiler controller, I already have the control box and so don't need to buy the STC1000, I can just adapt it with software.

For me (as I am sure it is for many) it is the inventing process I like as much (if not more) than using it when it is finished.

Why did you climb Everest? Because it was there!

 

[Papa G]

love to see this when you have this up and running Robbo.
The temp readings over a brew will be interesting to see.

 

[marksa222]

Good luck with this. Sounds like over kill to me, but by the sounds of it, you're combining two hobbies.

I'm pretty sure there was a similar project on Kickstart looking for funding for operating on a commercial basis. Was is brewtroller or something? Might be different, but it rang a bell.