Make sure your fridge can handle it! i just built a ferm chamber out of a fridge and the compressor must Barely be able to keep the stock fridge airspace cold. once i built it into a ferm chamber it is struggling to hold 68* internally. The ferm chamber is VERY well insulated so i know its not leaking air anywhere. However the exterior of the fridge where the cooling coils are had reached 145* at times. i have to have a fan blowing on it constantly just to keep it from shutting off. I am ripping the fridge out this weekend and putting in a window A/C unit. at least as a bonus i will gain more cubic inches with the swap.
That's part of why I posted this thread. I was hoping to hear about the successes and failures people have actually experienced with this kind of build (and others).
I believe I saw in another thread that many of the mini to counter height fridges use the same, or very similar, compressors. Regardless, based on my conservative calculations my chamber should only require around 100-125 BTUs to cool to 40F in 80F ambient temps. Everything I've found indicates that my mini-fridge should be capable of ~150 BTU. I'm also planning on using dry ice or other cold thermal mass to cool the chamber initially. With luck, my insulation will help reduce the work the fridge actually needs to do to maintain the chamber temps to something reasonable. I'm hoping the initial chill will prevent the compressor from being overworked from the get go.
I use an upright freezer and love it ... ferm temps to cold crash with a few clicks on the temp controller. I appreciate the DIY aspect of building a fermentation chamber from a mini fridge, but would recommend using a freezer. For those of you who built a chamber from a mini fridge, what was your total cost? For me, I pieced together a complete system using a freezer for around $200 ... as a bonus it pulls just over a kilowatt hour per week (sitting in a hot garage).
Here's my build:
https://www.homebrewtalk.com/f51/dutch-s-cadillac-fermentation-chamber-build-251579/
If I could have gotten away with another upright freezer purchase for my beer brewing addiction, I think I would have liked to have gone that way with my ferm chamber project. For now though, that's not in the cards. I'm also highly space constrained, so my build is a table/fermentation chamber combo. The whole chamber has to fit through a small doorway as well (~30in at its smallest), so a large upright freezer like yours would probably not fit. What are its base dimensions? I had to get a little creative with my woodcutting and sealing jobs.
I was able to piece my project together for a little over $200, but I had a few parts already laying around. I also modeled the whole build in CATIA, so I knew exactly what I needed from a materials standpoint. The bulk of my cost, by a long shot, was the insulation. I purchased five 4x8 sheets of .75," R5 RMAX insulation, and another two 4x8 sheets of .5," R3.2 RMAX insulation. At over $10 a pop, those added up quick.
