Setting temp controller temperature

I just got a fridge and a Johnson A419 controller. I've been playing around with it tonight and doing some temp readings off of a 6 gallon better bottle filled with water with the probe taped to the side then covered with several folded sheets of paper towel for insulation. The difference between the inside water temp and the outside is coming out to about 6 degrees. I also have a stick on thermometer on the bottle which seems to be matching the temp reading from the inside of the bottle.

I'm thinking I should set the controller temp to the difference between the two. Has anyone else done this? I'd like to keep the temp readings on the outside as I don't want to mess with a thermowell.

You might want to try something with more insulating power than paper towels-- it's critical to getting accurate readings of the beer temperature. I use a cotton hand towel, folded a few times and taped tightly against the temperature probe. Also, the probe must be taped securely to the side of the carboy to ensure good contact.

In the past, I've used a thermowell, but it's too much fuss. I have the same controller you do and use it on my Better Bottles.

-Steve

I have never done that, but how long has the water been in there for? I would think that if you let it sit in there over night the water should reach ambient temperature and all temperatures will be equal. Another thing to think about is that a 6 degree margin between different forms of thermometers is somewhat reasonable. But if that is that case then I would do what you planned on and set it in the median. Good luck!

The waters been in there for about 24 hours now, so everything should be equalized. The probe is taped directly to the bottle and then covered, but I'll give it a try with a towel. Thanks for the input.