Fermenation temp vs fridge temp

I've read that during active fermentation beer temp can be 10+ degrees higher than ambient temp. Does this rule apply to a small space, such as a mini fridge? I just picked up a second Sanyo 4912 to use for fermenting since it's getting hot in my apartment. What should i set my Johnson temp controller to if i want the beer to stay around 65 degrees?

I'm also assuming the way the probe is mounted affects this. Right now i've got it hanging at the top of the fridge, but i was considering submerging it in water or blue freeze pack gel if that would yield more accurate control.

jamil says tape it to the side of the carboy and surround it with Styrofoam so that it takes temp from the carboy and not the ambient air

Opherman47 said:

jamil says tape it to the side of the carboy and surround it with Styrofoam so that it takes temp from the carboy and not the ambient air

Click to expand...

That's a good idea. Thanks

Opherman47 said:

jamil says tape it to the side of the carboy and surround it with Styrofoam so that it takes temp from the carboy and not the ambient air

Click to expand...

That's only applicable for the digital controller. Using the analog, you're better off just leaving the sensor in open air and monitoring ferm temp via a stick-on thermometer because the analog unit has a 4 deg differential.

Ditto
If you have the digitial controller you can adjust the differential to 1 degF and tape the probe to the side of the fermenter and cover it with insulation. Don't put it into another jar of liquid, that only increases the time constant.

I have the dial version, so apparently that won't work. Maybe keeping the probe at the top of the fridge will help compensate for increased temps during fermentation since cold air sinks?

Gritsak said:

I have the dial version, so apparently that won't work. Maybe keeping the probe at the top of the fridge will help compensate for increased temps during fermentation since cold air sinks?

Click to expand...

Just slap a stick-on thermometer on the fermenter and adjust the JC accordingly. Air temp will fluctuate 4 deg but you'll find the fermenter stays constant because of the thermal mass.

I've been wondering the same thing-thanks for all the info!