Fermentation Temperature Control

Yeast & Fermentation
1

I purchased the Johnson A419 controller with plans to use it both in my chest freezer for lagers and finished kegs, as well as controlling an electric fermenter heater. Trying to be super accurate, I was planning on dropping the thermistor into the fermenter. After receiving the controller, I’m having second thoughts about putting the thermistor in liquid. Does anyone know if this is acceptable or should it be avoided? If I cannot immerse the thermistor, what are the best methods for getting the most accurate temperature reading?

Thanks

2

I put mine in a zip lock bag and then put it in a container of water inside my fermentation fridge

3

Use a bungee cord to hold the sensor against the side of the fermenter with an inch of foam insulation over the sensor.

4

This is probably the most accurate way to control the ambient temperature within the fridge. The water will act to buffer any disturbances (like happen when you open the door) so the fridge motor doesn’t go crazy and work to overcontrol the situation. However, the temperature of the beer could be a few degrees warmer than the air inside the fridge if the fermentation is very active.

Taping the sensor to the outside of the fermentor (possibly with a piece of foam between the sensor and the air) gets around this problem, and the beer then buffers against any transient swings. And no worries about sealing the fermentor or contamination.

5

I use a thermowell.