I started out using a large bucket and frozen bottles of water to do adjustments. That seemed to work quite well. But, someone had a nice small freezer for sale and I bought it. I had a separate controller to allow it to work at fermenting temps.
Well, I'm not quite such a happy camper. The freezer works well to get temp down.. but there are some pretty big swings in it. I don't think the insulation is worth a cr@p.. or.. maybe I'm just expecting too much???? It seems to have a LOT to do with ambient temps. I have my freezer on the back porch.. out of direct sunlight.. Ambient here.. at this time of year can vary a LOT from early morning low 50's to the hot part of the day, high 70's to low 100's
I currently have the freezer set at 68*. When I wake up in the morning, ambient is in the low to mid 50's. Right now, the freezer is reading 62* and during the day it will get up to about 70*. I decided to turn the freezer off and see what happens. Well, inside the freezer it got down to 62* in the morning and went up yesterday afternoon to 74* I'm thinking the insulation sucks. It's an older freezer. I don't know if the newer ones are better insulated or not. I'm sure if I had more than one carboy in it.. the temp would stabilize a bit more... but, right now.. it's a 5 G batch cooking.
It almost seems that I may have to get a dual controller of some sort to connect to a heat belt or ???.. but not sure what I'm going to do yet..