Fermentation gradient between carboy and outside air.

[peoplesbrewingcoop]

I will be brewing my first lager in a few weeks and I wanted to get some information. I recently got a 15 cubic foot freezer that I will modify into a fermentation chamber for lagers, wines, and sake. I have not yet brewed at a temperature lower than 22C (72F).

When brewing at 10C (50F) should I put the sterile temperature probe in the fermentation carboy to make sure the temperature of the beer stays at 10C or should I leave the probe on the side of the bottle? Generally, what amount of heat does lager yeast generate in a 5 gallon sample?

I ask this because I usually incubate small samples at a set temperature thus the temperature of the sample will be the same as the air outside the container holding the sample. When using a large 5 gallon sample then there would be higher gradient between the active fermenting yeast and the air inside the fermentation chamber. Does anyone know what impact this would have on flavor or am I over thinking this?

Thanks in advance for the replies.

 

[mojotele]

I usually just use the Fermometer liquid crystal things and they seem to be surprisingly accurate (I tested it against my calibrated thermometer). As such, I have my probe taped to the top of my chest freezer. I adjust the temperature by reading the Fermometer. If it is too high by 2 degrees, I lower the temperature by 2 degrees. Simple as that.

In my limited experience, lager fermentations at 50*F don't seem to generate much heat at all. I had my controller set to 50*F, and the beer seemed to bounce between 50*F and 52*F. With ales, I've had to set my controller several degrees lower than the actual fermenting temperature.

 

[peoplesbrewingcoop]

Thanks, for now I think I may just let the outside air be regulated, but I will record the temperature within the carboy to see how much heat is being generated during fermentation.