Building a fermentation chamber

[abw73]

I have some of the parts, but still need the wood and insulation. Need to clarify a few things before I start.

My mini fridge is 4.3 cu ft, extending it to hold 3 fermenters at once, and I want to be able to lager and cold crash. Also have 250w space heater and a small desk fan for circulation. The temperature controller is an Inkbird 308. From my research so far, this seems sufficient. Any feedback on this?

1. Floor. I plan to put particle board down with insulation over the top. I see some with foam board floors with the silver/reflective surface. I saw board insulation at Lowe's, but it doesn't seem very strong. My fear is a full bucket or carboy would crush or damage it. Not one person I could find discussing their build addressed this. In fact, most only showed an empty floor.

2. Insulation R value. The same foam I mentioned above at Lowe's is about 6. I read that refrigerators are usually about 12. No chamber I saw had any kind of batting or other insulation. It just doesn't seem like a single 1" foam board would be enough at R 6.

3. For those who have built a chamber with a fan, do you leave it running constantly to keep air circulating, or turn it off periodically?

4. Not a question, but I plan to use insulation tape and caulking to seal everything.

So far I have been researching builds for almost 2 weeks, here, google images, blogs, anything I can find. The pictures are great, but so far none have addressed these concerns. If I have missed a thread, please let me know.

 

[crazyjake19]

Avoid EPS foam, which is essentially styrofoam, sometimes with thin foil. This has the lowest R-value per inch and would likely crush with some weight on it.

Look for XPS foam (usually pink, purple, sometimes blue) or PolyIso foam (usually a yellow-ish core with foil on both sides). They are more dense, less crush-prone, and have a higher R-value per inch. They're also cleaner to cut and install.

I'm currently in the stages of building a similar fermentation chamber project and I'm using some 1.5" XPS foam just because I had an extra sheet from other projects. The sides I may leave with bare foam but on the bottom I'm using some 1/4" thick composite sheets that were actually the sliding panels from our local Lowes that covered the items in the top stock. They're not super thick or rigid, but I figured they would spread the load more evenly over the insulation, and make it easier to clean up any minor spills.

I plan on putting a small fan in mine and running it 24/7. I've heard of other people setting their fan to run only when the fridge/freezer/keezer cycles, but in my keezer I run it 24/7. It's a 12v fan drawing 0.23 amps, so it's quiet and moving the air just enough to keep an even temp. One thing to consider is that you don't want such a powerful fan that you're actually adding heat to the space when you don't want it.

 

[mcl]

I don’t think you will be able to cold crash with this setup. When I built mine I put plywood on top of the foam board for the floor. This will help with durability.