Inkbird swings

[puzx]

Hello,
I am a new homebrewer and was wondering if someone else was experiencing the same with the Inkbird ITC-308 as I do. I use a chest freezer as my fermentation chamber, plug it with an ITC-308 to control the temperature.
I set my inkbird at 68 degrees and put the probe inside the freezer , hanging on the air. I have noticed that the temperature swings by a lot more than the 2 degrees HC/CD I have it set. Example, I observed my temperature go all the way down to 61 degrees, which scares me as being too cold. It does come back up to 68, but it takes a few minutes or so.
Is that normal or does everyone else’s Inkbird temperature fluctuations stay much closer to the set temperature?
I am just wondering if it’s a defective unit.
Also, I have it set as 0 for PT, is that recommended?
Thanks!

 

[RM-MN]

I am just wondering if it’s a defective unit.

Not defective, you're using it wrong. You don't care how hot or cold the air in the freezer becomes, you care about the temperature of the fermenting beer so let the Inkbird see the beer temp and let it change the air temp to keep that within its range. Tape the sensor of the Inkbird to the fermenting vessel, then tape some insulation over it.

 

[hotbeer]

The thermal mass of your heating unit or cooling unit might also be overrunning the cutoff temperature.

IE, when your cooling unit shuts down, it might have cooled all of it's surfaces down much lower than the target temperature whether ambient air or actual beer temp. So the temperature continues to drop as things equalize between the already cooled down refrigerator and the things in it.

This happens quite often for me when I first start out and the temp of the beer is quite a bit different than where it needs to be. After 24 hours it mitigates to some extent. But if still an issue after 24 - 48 hours, then definitely something in your system setup is amiss.

 

[VikeMan]

^ This is pretty common with freezers, IME.

 

[Jim R]

Tape the sensor of the Inkbird to the fermenting vessel, then tape some insulation over it.

Agree with this. The probe works best with the one fermenter That I use with an internal thermal well so the probe is right inside the fermenting beer. The next best option is to tape it to the outside of the fermenter as mentioned above with insulation over the top of it. I even bought a cheap foam insulation mat (an exercise mat) from Walmart and wrap it around the entire fermenter with the Inkbird probe taped to the outside underneath the insulation. This eliminates all of the swings in the air as the freezer turns on and off. I doubt that your Inkbird is broken.

 

[jsphlynch]

Concur that this is completely normal, as all the parts that got very chilled continue to cool the air in your chamber after the compressor is shut off. You can think of it as a cooling inertia. I sometimes have a bit of frost start to form on one section on interior surface at the end of a cooling cycle.

As others have said, tape the probe to the side of your fermenter. The thermal mass of your beer will dampen the temperature swings, plus you care more about the temp of the beer in the fermenter than you do about the temperature of the air around it.

If you're only cooling, setting the PT to 0 is ok, though I would set a little bit of a delay (1-3 minutes) just to make sure a random short temperature fluctuation doesn't pointlessly turn on your compressor a few seconds. I have a heating mat inside my freezer, so I set my delay to a few minutes to ensure that the heating/cooling inertia doesn't cause the chamber to constantly cycle between heating and cooling.

 

[mac_1103]

I even bought a cheap foam insulation mat (an exercise mat) from Walmart and wrap it around the entire fermenter with the Inkbird probe taped to the outside underneath the insulation.

Doesn't that make it harder to cool the beer inside the fermenter? Seems like you're working against yourself this way and I'm pretty sure that insulating only the probe would be just as effective at preventing the temperature swings.

 

[Moose_MI]

I use the itc-308 in my ferm chamber…i bungy cord around the bucket and slide the probe down between the ferm bucket and a dish sponge.
Im sorry to say this works really well..damn you inkbird for being so awesome. I really want a jacketed conical but the $30 inkbird is just too perfect. My temps stay within 1 degree of set temp…it just sucks

 

[Jim R]

Doesn't that make it harder to cool the beer inside the fermenter? Seems like you're working against yourself this way and I'm pretty sure that insulating only the probe would be just as effective at preventing the temperature swings.

I think insulating the whole fermenter (or my kegs after fermentation) reduces the cycling of the refrigerator. It takes longer to cool the vessels down but then after the refrigerator shuts off and the temperature inside slowly drops, the vessels retain their temperature longer allowing the compressor to cycle less often. I have suspected that longer but fewer cycles is easier on the refrigerator plus it is heavier foam insulation over the probe.

I also then use the foam wraps on the kegs if I travel with them.