Why won't my temp stay stable? Idylis 7.1 cubic freezer/inkbird itc308

[Brochubrew]

I purchased a Idylis 7.1 chest freezer this weekend from Lowes to serve as my fermentation chamber. To control temperature, I connected it to the Inkbird ITC-308 digital controller. The controller is most certainly regulating the temperature to some extent, but when the compressor kicks on to cool it is running way too long and bringing the temp down too much. I'm only testing the setup now before I brew and have something in there, but here is what I am seeing

* Freezer is in the garage (unheated/uninsulated). It has been mid/high 80s all week, probably gets about 75 in there during the day
* Setting is for 63 degrees F
* Range (high/low) is set for 1 degree F (should only be as warm as 64, and as low 62)
* Compressor delay is set for 0 - there is no logic being used to delay based on previous on/off schedules
* Freezer setting is at the lowest possible setting (it shouldn't turn on max when its running to cool, but should slowly cool)

When the temp dips below 63, cooling turns on - great! However, when it does cool, it dips down to 54 degrees and I'm alerted with an alarm. Thats way too much fluctuation for a fermentation.

One note - when I am testing, I only have the probe sitting inside the chest freezer itself. I'm wondering if the fluctuation is so great because the probe is out in the open, and in order to cool it down the freezer needs to run for a while to lower that small space. Maybe it gets better when its in a liquid? Right now I just put into the freezer a glass of water with the probe in it to test it out when its taking a reading from the liquid and not ambient temp.

Anyhow - has anyone ever had a similar issue? Is there something else I should be considering? Any info would greatly be appreciated.

 

[doug293cz]

Adding the fermenter to the freezer will reduce max/min temp fluctuations. Right now there is very little thermal mass in the chamber. That's why it undershoots. Best probe location for a fermenter is taped to the side of the fermenter under a bit of foam insulation. This gives you (mostly) the temp of the fermenting beer, and since fermentation generates heat, you really need to control based on the beer temp, not ambient temp or temp in a vessel of water.

The max/min setting on the freezer itself is a thermostat setting only. It just turns the compressor on/off. There is no variable cooling rate available. Cooling is at full or off.

Brew on

 

[day_trippr]

Totally agree, though I would stress the importance of isolation and go with something equivalent to the inch thick closed cell foam pads I use over my temperature probes.

Wadded paper towel or a sock are right out

Cheers!

 

[MaryB]

Set you compressor delay to at least 3 minutes or you can get compressor lockup on a power outage.

I use a chest freezer for my main fridge(runs via solar, super high efficiency) and the probe is halfway down the back wall measuring air temp. Varies from 37 to 40 degrees...

 

[bigdawg86]

I agree with needing to tape the temp probe to the side of the fermentor with packing tape, then tape something thick over it to insulate it. I purchased a thermowell but found the same problem you are having.

In the picture setup below I installed a separate temp gauge to the keezer collar and then on the wall is the temp controller. For my next batch I will place the standalone temp gauge in the thermowell, and then tape the temp controller to the side. I think this will give me a good idea of wort temp / freezer temp split and dial up or down a degree or two at a time until I reach equilibrium.