BeerBorg

Got a new (to me) mini fridge and I'm having some difficulty getting the temperature down on my STC-1000.

My old fridge did a pretty good job of keeping temp when the probe was placed along the door. I always compared the temp to that of my temp strip on my bucket and was usually within 1 or 2 degrees.

This fridge, I'm not having such luck, so I've got the probe taped along the back wall. There's nothing fermenting in it right now so I can't give indications as to accuracy.

Besides running the probe through a thermowell in the bucket when there's something fermenting, is there a place inside the fridge that usually works best for measuring temps?

I have heard of people moistening a towel or sponge and putting it in a ziplock back along with the prob and sealing it up. Not a long term solution but it will let you know how accurate things are and help determine where the best place to mount it might be.

My first though on the subject line was, "That's what she said" but I'm still in high school. But, I tape mine to the side of my bucket because I don't trust those temperature strips.
I also have a USB computer fan running in my box which helps keep my unit pretty even all the way around.

When I saw Paul responded, I had to close my virgin eyes and peak! Glad it was safe to look at his comment. My probe is just dangling in my keezer, ( easy Paul, I know I lobbed a beach ball at you! ) it seems to do ok, but with the fridge maybe dangle thru a shelf rack.

I'm thinking I might need to look into a fan to circulate the air. It seems that the cooler air is all the way at the back and the front is a lot warmer. I've got a keg of steam beer and my co2 bottle in there right now carbing away and I want it to be about 50F in there.

I put mine on the side of the fermenter below the wort line. With a paper towel (folded) between the tape and the probe to help insulate it from air changes.

I put water in one of the infamous Mr. Beer 1-liter PET bottles, place that in the fridge, and stick the probe in the water. I figure, it's measuring the temp of a liquid in the fridge, which is exactly the point of the whole process.

(We ARE still talking about external temperature probes....aren't we?! )

99% of the time it's in a thermowell in the wort. 1% of the time it's on side of the bucket with a folded hand towel over it secured with a bungee cord. If no beer is in the fridge, it's just dangling from a shelf.

I do the same as Inkleg. Taking the temp of water doesn't make sense to me, as during peak fermentation it doesn't heat up.

Crazy Climber wrote:I put water in one of the infamous Mr. Beer 1-liter PET bottles, place that in the fridge, and stick the probe in the water. I figure, it's measuring the temp of a liquid in the fridge, which is exactly the point of the whole process.

That doesn't account (directly) for the temperature increase of the wort during active fermentation - it's buffering it by how much it heats the ambient air temperature and then how long that takes to heat up the water in the other container - which would make temperature adjustments of the fridge happen much slower then needed to try to keep a more stable fermenting wort temperature.

So it depends on if what your trying to accomplish is to keep the fermenting wort at a certain temperature, or just keep the ambient air temperature within a some buffered temperature range (and it will be a range due to the buffering effect). Doing it the way you describe your wort is heating up many more degrees above the temperature you set and fluctuating in temperature quite a bit.

Still better then nothing I suppose, but maybe not the intended effect.

Tape it to the side of fermenter to control fermentation not air temp.

I have the temperature probe of my digital controller inside a 12 inch long thermowell that sits submerged in the fermenting beer. I also have another digital thermometer dangling inside the freezer to measure the ambient air temperature. It's interesting to watch the seesaw effect that takes place as the compressor kicks in to lower the ambient air temperature which eventually lowers the fermenting beer temperature too.

With the set point of the controller set to 65F it's not uncommon to see the ambient air temperature dip to 60F and raise to 70F before the 10+ gallons of fermenting beer reaches the set point again. I keep the hysteresis set to .5F to trigger the compressor or heater whenever the beer temperature drifts below 64.5 or rises above 65.5F, its kind of entertaining to watch.

When I first setup my chest freezer with the STC-1000+ controller using 2.5 gallons of water in an Ale Pail fermentor the temperature swings were a lot more frequent. It seems the more volume of liquid there is to heat or cool the less frequent and pronounced the seesaw effect is. Now after chilling my wort from the kettle to the fermentor and placing the fermentors in the chest freezer to get the temperature down to 65F, the seesaw effect is a whole lot less.

mashani wrote:

Crazy Climber wrote:I put water in one of the infamous Mr. Beer 1-liter PET bottles, place that in the fridge, and stick the probe in the water. I figure, it's measuring the temp of a liquid in the fridge, which is exactly the point of the whole process.

That doesn't account (directly) for the temperature increase of the wort during active fermentation - it's buffering it by how much it heats the ambient air temperature and then how long that takes to heat up the water in the other container - which would make temperature adjustments of the fridge happen much slower then needed to try to keep a more stable fermenting wort temperature.

So it depends on if what your trying to accomplish is to keep the fermenting wort at a certain temperature, or just keep the ambient air temperature within a some buffered temperature range (and it will be a range due to the buffering effect). Doing it the way you describe your wort is heating up many more degrees above the temperature you set and fluctuating in temperature quite a bit.

Still better then nothing I suppose, but maybe not the intended effect.

Should've mentioned that I also have a stick-on thermometer on the fermenter, to keep track of early-fermentation spikes, and adjust the controller to reduce the ambient temp accordingly. The probe-in-water is primarily to keep liquids in the fridge (e.g., the bottle of water and the beer in the fermenter) at the desired temp for the 80% of the time that active fermentation is not generating notable heat.
Submerging the probe doesn't accomplish anything that letting it measure ambient air couldn't do, but it does result in longer on/off cycles, thus helping to prolong compressor life.

I'm a thermowell guy since I got my STC-1000 but before that I used to let it dangle near the front of the unit. I knew how much variation I had during fermentation so I just buffered accordingly.

I've finally been able to get the fridge to 50 degrees but it's not likely it'll go cooler than that. I guess this will be strictly a fermentation fridge for ales and hybrids. No keg chilling