How many people are using thermowells to control based on the temp of the wort instead of the air in the ferm chamber?
I do. I can not see the merit in doing it any other way.
I have a mini-fridge with the shelving removed from the door, and I can
just fit both my 5 gallon or 6 gallon carboy into it (one at a time). The fridge is just set for a medium setting, and left to run as normal (plug and go). The carboy is treated with a fermwrap, attached to a johnson control, and the probe is run down into a carboy cap thermowell (morebeer manufactures the carboy cap thermowell in house). It does not fit really tight, but I found stoppers to be a nightmare, so I switched to carboy caps.
By hooking the controller to the fermwrap, this means I still have a working fridge. I think it is the best choice for a few reasons. The freezer compartment still works, and stores my hops. The fridge still works, and there is a small compartment to store my yeast. Additionally, I am not cycling a fridge on and off, so I have to imagine it is a little easier on the appliance. Finally, and most importantly, I am setting the temp on the controller to regulate wort, not air. I just close the wires in the door, and the fridge seals fine. Sometimes I put a dumbbell in front of the door for a little added insurance that things stay sealed.
We all know that ambient temperature is not a great indication or wort temperature during fermentation. I am sure it is fine to control air temps when you are keeping a keezer from freezing, and you are only concerned with maintaining a ball park serving temp, but not for fermentation. If you are going to go as far as putting a controller on your fridge, why not go a little futher and control the wort. The fermwrap and thermowell are minor investments. I do not care about the air temp in the fridge, I care about the temp of the wort. Also, due to the mass of the carboy relative to the small about of air space in the minifridge, temp swings of the wort are few and far between, so even with a 1 or 2 degree allowance on the controller, it is not like the heater is constantly firing on and off. The temperature is dialed in, and for the most part, stays steady.
I do not think this point is brought up often enough. I have tasted first hand the difference between a beer fermented with a particular yeast at 68, and a beer fermented at 66. Two degrees makes a big difference.
If you are only measuring the air, how well are you able to gauge the wort?Ambient is fine for serving, but for fermentation, I really think you need to be controlling the wort.
Joe
