Thanks to many ideas from this forum and around the web I've completed my fermentation chamber. The original idea came via a Son of Fermentation Chiller, but I wanted to plumb in some old fridge guts instead of having to swap out ice buckets. Well, a few weeks ago someone left a dorm fridge in the office breakroom with a note of "Free or Trash", so I was good to go. I didn't take any pics of the fridge guts removal process, but it was a pretty ugly process... hack saw, tin snips, chisels, hammer, etc, etc. It still cooled when I got it out, so I guess I was gentle enough at the right times.

It's a pretty standard foam box made of glued up Foamular 250. I couldn't find any 1 inch board locally, so I just glued together .5 inch boards. After some trials on the best way of cutting it I arrived at a razor and straight edge as the cleanest method. Cutting about 3/4 of the way through allows you to break off the rest with a pretty clean edge. I wrapped most exposed corners with aluminum tape for some extra durability.

Here's a shot from the outside, with a 5g BB for size reference:


To mount the fridge parts I built a frame of 2x4s screwed to a base piece of plywood, to which the foam box is also glued. I added a cross member to the frame to get the whole compressor assembly to the right height, and it also worked out to the right height and width to mount the condensor using the stock screw holes.



For the inside I built it with two chambers, with each big enough for a 6.5g carboy and blowoff bucket, or two corny kegs. The left chamber as you can see holds the cooling element from the fridge. The divider is removable since I have to slide any left chamber contents in under the cooling element.



The right chamber will be the warmer of the two. Based on ambient temperatures and the temp of the cooling chamber, I'll either be warming the right chamber via a heating pad, or I'll be cooling it with a muffin fan (yet to be installed) to exchange heat with the left chamber. Here it is fermenting with the heating pad. For these shots the cooling chamber was keeping the keg at 45F, and the heating pad keeping the carboy at 68F. I didn't time it closely, but I'd guess the heating pad was running every 30 minutes in this configuration, and about the same for the fridge.



I'm using a Johnson analog controller to control the fridge and left chamber, and a repurposed home thermostat rigged with a remote sensor to control the right chamber. The tstat is switching two 12v/120v relays in the electrical box, either heat or cool, based on whether I'm using the heating pad, or the yet to be installed muffin fan. If I were to do it again, I'd scrap the home tstat and use one of the ebay aquarium controllers, but it seems to be working fine.



I guess that's about it. It's big, pink, and ugly, but it's sitting in an unused storage room, so it's out of sight. It's doing a fine job though, and compared to adjusting space heaters and wet towels in a bathtub it's a dream. The only thing I miss is being able to sit and watch the fermentation churn in the carboy, but being able to "set it and forget it" is worth giving up that little bit of entertainment.

Cheers!