Fermentation generates heat!

[Kazi the Younger]

I brewed a german pilsner last weekend. Did a starter on a stirplate and pitched a bunch of healthy yeast at about 48 degrees into 48 degree wort. Nice thick head of Krausen after 12 hours. Carboy is fermenting in temp controlled fridge set to 48.

36 hours later I check the temp of the outside of the carboy--it's up to 56 degrees! I guess I ought to
put my fermenter in a tub of water in the temp controlled fridge that will keep it at a constant temp when the temp probe is submerged in it.

How do you guys control the huge heat gains that can occur with fermentation?

[Frankenhop]

I guess I ought to put my fermenter in a tub of water in the temp controlled fridge that will keep it at a constant temp when the temp probe is submerged in it.

How do you guys control the huge heat gains that can occur with fermentation?

You answered your own question.

[ApresSkiBrewer]

You can use a thermowell probe... (heh) and have that right in the beer... so it isn't controlling ambient temp, but the actual temp of the beer.

But I have read/heard/somehow acquired that if you stick the probe right to the glass, its within .5-1 degree of the beer inside the carboy, so that is sufficient to make sure you are controlling beer temp.. not ambient temp. Just be sure that you cover it with some form of insulation, so that when the blower of your fridge turns on and blasts the probe on the outside with cold air, it doesn't F the reading.

[oneal66]

Just be sure that you cover it with some form of insulation, so that when the blower of your fridge turns on and blasts the probe on the outside with cold air, it doesn't F the reading.

This might be your problem, you really need to insulate your probe.

[ColdBraue]

Just be sure that you cover it with some form of insulation, so that when the blower of your fridge turns on and blasts the probe on the outside with cold air, it doesn't F the reading.

This might be your problem, you really need to insulate your probe.

It's good to wrap your probe.... hehehehehehe.

[Pseudolus.]

Couple of bungee cords around bucket. Doubled-over sheet of bubble wrap tucked under bungees to make a little pocket. Probe of temp controller tucked into that. So I turn the freezer on and off based on the temperature of the beer, not of the air around the beer.

[Kazi the Younger]

Ok thanks guys, I'll be sure to wrap my probe next time I take a plunge.

[ApresSkiBrewer]

Ok thanks guys, I'll be sure to wrap my probe next time I take a plunge.

Nice. Always a good policy.