cwi

Recipes 

It is tricky to do this, and I don't know if I would attempt it without a thermowell placed close to the inner wall. It is surprising how much impact the ambient air has on the sensor when taped to the outer wall, then insulated. No amount of insulation seems to be too much to still have some impact of ambient on the sensor. This is advantageous when using a freezer/fridge to control ferm, since it helps prevent over/under shoot, as well as radial stratification (which is an issue when using a thermowell in the center).

smata67

Recipes 

This is how I've been brewing for 2 years now. Probe is buried in insulation, reads the bucket's temperature. I threw out the door and replaced with an insulation panel which makes it easier to move the bucket in and out. The Ranco has a 2 degree offset to prevent over-cycling. Fridge thermostat is at highest (coldest) setting. Notice the avocado color on this garbage day pickup fridge, it is probably 40 years old and still going strong, pulls down to 35 F! National Panasonic Made in Japan fridge!

cwi

Recipes 

The offset/differential setting is no help against 'short/hot cycling'. This is where it starts up again very shorty (<5 minutes) after it has just finished running. This can kill a compressor in a matter of hours, or less. Short cycling can easily happen as a result of events like door openings, temporary power losses, or the probe coming loose.

A controller with ASD has a built in delay (usually adjustable) to prevent 'short cycling'. With ASD, it is possible to set the temperature differential/swing as low as 0.5F without worrying about short cycling. The mass of the beer keep cycling frequency well within limits.

The Johnson digital controllers have ASD, as do the $15-25 ebay DIY controllers. The $25 one is even dual stage, and will automatically switch between heating or cooling.