I just built a fermentation chamber for my garage. (See My Letter to SWMBO)
I’m using a temperature controller and tried taping the probe to my carboy while covering it tightly with thick insulation. However, every time I opened the chamber door, within seconds the temperature displayed on the controller would rise several degrees. That told me my probe was measuring air temps, not wort temps.
Last night I moved the probe into a growler of water. Now, when I open the door for a few seconds, the temp does not change.
Is this the best solution or should I try to find a better way to affix it to the carboy?
Better check to make sure your probe is waterproof. I don’t believe mine is (Ranco). You could put it in a dry tube in a jar of water and seal it off & be safe. Duck Tape and a piece of foam insulation has always worked for me… Cheers!!!
The probe looks like a tiny square of plastic. It came with the STC-1000 I’m using. I’ll post a pic of it later. I assume it’s waterproof. I’ll experiment again with some foam insulation and make sure it’s entirely sealed by tape. I might need to replace the cheap plastic probe with something that may be more accurate.
I use packing tape to affix the probe to the side of the carboy, about midway up from the top of the wort level. Then I fold a handtowel several times, put it over the probe, and wrap some packing tape around the carboy to hold the towel firmly in place.
Been doing it this way for 3 years, never seen the temp change from opening the lid.
If you can get a stopper with 2 holes buy or make a thermowell to go inside the fermenter. I made mine from the diptube of a dead keg. I cut it so that it would be long enough to get to the middle of my fermenter, then folded and soldered (silver solder)the end so it was sealed. You’ll have absolutely the best temp measurement possible.
I pretty much do the same thing although I use a piece of a packing styrofoam sheet taped to the side like a little pocket, then I slide the probe into it so it’s in contact with the carboy. Saves wrapping the whole carbooy in tape.
The controller will work best by measuring the fermenting wort. A thermowell is best, but taping it to the side of the fermenter covered by insulation is a close 2nd. Placing it in another liquid far from the fermenter is the worst choice.
Taping some plastic sheeting (ziptop bag, styrofoam, etc.) to the side of the fermentor and slipping the probe into it works very well. Back in the day when I fermented in carboys, I used one of these, and it also worked very well:
This is true. Where the probe is crimped to the wire is a little wider than the thermowell. I filed down the “fins” created by crimping with an emory board carefully enough to fit the thermowell. I should say that I have the Johnson a419 and the thermowells, bought within the past two years from two different shops, IIRC Northern Brewer and Midwest supplies.
Well there’s a big difference between “opening a lid” and “opening a door.” It’s not a great idea to keep opening a fermentation chamber with a door- of course all the cold air will spill out. After 12-24 hours I’ll peek in to see if there are signs of fermentation beginning and if I see it I don’t open the chamber for a week- sometime longer.
My “probe” hangs about halfway down the chamber wall supported by a piece of Styrofoam. I have a thermistor attached to the end of a long thick copper wire inserted into a dry plastic vial. This long wire measures the ambient temp of the chamber next to the fermenter and hangs off the lid of the fermenter in the pic. The fan stirs the air around keeping convection going and blows directly on both probes.
So far when I measure the temp of the beer with my super-fast Thermapen it matches the temp of the surrounding chamber even at the height of ferment.
I have a Johnson A419, and the probe fits into the thermowell I bought from Northern Brewer a few years ago just fine. It sounds like that isn’t the case for everyone though. There must be a bit of a manufacturing variance.
