I recently built an eHERMS control box using an Auber PID/SSR. I'm curious if I can make this a dual-purpose controller... On brew day I'll use it to control the heating element in my HLT, and then I'd like to use it as a temperature controller for my small fridge that I ferment in... Right now I do not have the ability to set a specific temperature with the fridge. When I set the thermostat on it's warmest setting it holds right at 64F and that has worked just fine so far, but I'd like to be able to set a specific temp. My plan is to use a spade bit to cut a small hole into the side of a Better Bottle, and then use a drilled stopper to hold a 4 or 5" RTD probe in direct contact with the fermenting beer. I know my PID can be set to 'cooling' mode, but I'm not sure if that will throw it off when I'm using it in 'heating' mode. Any thoughts on this idea?
My other concern is fluctuations in temp inside the fermenter. If I have it set to 64, I assume that when the controller kicks the fridge on, it will run and get quite cool inside the fridge before the beer actually cools back to 64, and then once it kicks off it will still be quite cool and continue to cool the beer for a bit...