Freezer Fermentation Chamber Project

Update April 2020

I've built a second fermentation chamber and I made a few tweaks to the design

Update January 2020

I've made a few changes to the fermentation chamber after using it for the last 11 months.

Background

I've wanted to have better control over the fermentation temperature of my beers for a while. Placing my carboy in the closet and hoping for the best has yielded some good beers and some that weren't so great.

Overview of the Chamber

I'll be using a BrewPi and a freezer to control the temperature of the fermentation process. I like the BrewPi because it's using a Rasbperry Pi (I also like to tinker with computers and networking). I went with a freezer vs a fridge so that I can do cold crashes without any worries. There will also be a heating pad in the freezer that the BrewPi will control to provide any heat needed.

Parts List

This includes almost all of the parts I used to build the fermentation chamber
  1. Magic Chef 7 cu. ft. chest freezer (model HMCF7W3)
  2. BrewPi Spark 3
  3. Rasbperry Pi 3 Model B
  4. 10A Solid State Relay
  5. 40A Solid State Relay
  6. SSR Heat Sink
  7. Onewire Temperature Sensor (2)
  8. Wall mounted onewire temperature sensor (for the fermentor bucket)
  9. Brewer's Edge Space Heater from William's Brewing
  10. Red and black 18 AWG electrical wire
  11. 18 AWG ring terminals
  12. 16" stainless steel thermowell from Brewers Hardware
  13. Two hole rubber stopper (to fit the thermowell and airlock on the glass carboy)
  14. Corsair ML120, 120mm Premium Magnetic Levitation Fan (2-Pack) Amazon link
  15. DC Power supply for 3 or 4-pin 12V PC case fans Amazon link
  16. NOT NEEDED ANYMORE: Various 4" and 3" ABS couplings and 3" ABS pipe for the fan ducting (detailed list below)
  17. NOT NEEDED ANYMORE: ABS pipe cement
  18. 2 x RJ12/RJ11 Straight telephone inline coupler Amazon link
  19. 2 x 3 foot RJ12 cables Amazon link
  20. 3/4" x 2' x 4' Birch Plywood
  21. 1" x 4" x 8' and 1" x 4" x 6' Hemlock Boards
  22. Pink rigid insulating foam (optional)
  23. Screws/staples/glue/tape for attaching the plywood, hemlock, and foam
  24. Spray Polyurethane, water based, semi-gloss
  25. Construction adhesive
  26. Three colors of 14AWG wire
  27. 1/2" x 2' x 4' Birch Plywood
  28. Two door hinges (4 inch x 3 3/20 inch Tee Hinge) Home Depot link
  29. Small screws, nuts to attach the PC fan to the hinge. I used M4 x 35mm bolts and M4 hex nuts.
  30. Some scrap pieces of wood for the fan and hinge assembly
All of the pictures

Part 1: Build the Freezer Frame

I was looking at the wires I needed to run into the freezer and I quickly realized that I couldn't run them through the freezer drain hole. I was not keen on drilling through the freezer wall and risk hitting electrical wires or cooling coils.

I had been doing some research on building a keezer and realized I could adapt the concept of using a wood collar from a keezer for this build. This would allow me to drill some holes through the wood and be able to run cables into the freezer.

My plan is to use 3/4" plywood for the frame with some hemlock on the outside of that to give it a nice look. I plan on using some rigid foam board on the inside of the wood collar to provide a good insulation barrier. I could have easily used 2x4's, but I had strict orders from the wife that it not look like crap. Okay!

From the Parts list above, this will involve parts #20 through 25. Everything in this part of the build was obtained at Home Depot or Lowes.

If you're repurposing a used freezer, this would probably be a good time to give the insides of the freezer a good cleaning.

Pictures from part 1 of the build

Part 2: Locate PC Fans in Freezer

To keep the temperature more consistent in the freezer, it's best to use some sort of fan. I got the idea of using PC fans and some PVC pipe from this article on the Homebrewers Association forum. This setup pulls the cold air from the bottom of the freezer to the top through the PVC pipe.

(UPDATE January 2020) Using PVC pipe was a neat idea, but I found that it just got in the way. I removed ABS pipe and mounted the fan on a pair of door hinges on the back collar of the chamber. This still provides air circulation and I can move the fan aside while removing or placing a carboy in the freezer.

From the Parts list above, this will involve parts #14, 15, 28, 29, 30. Everything in this part of the build was obtained at Amazon or Home Depot.

The size fans I selected are probably severe overkill for the amount of air I need to move, but it's a fun project. I wanted some fans with a high CFM (these are supposed to be 75 CFM).

I decided to position the fan to the right side of the chamber, but not above the hump where the compressor is. I attached the fan to the hinges, then cut a piece of scrap wood that the hinges would attach to. I attached the hinges to the scrap wood, then attached the assembly to the collar.

To make the fan stop from falling down, I screwed another piece of wood to the hinge (behind the fan) to act as a stop.

Pictures from part 2 of the build

Part 3: Load Software on the BrewPi and Raspberry Pi

I decided to get the Raspberry Pi and BrewPi working before building the panel to check that they work.

All of the instructions for this step are pretty well documented on BrewPi's website, so I won't bother with duplicating them here.

Obviously the BrewPi was purchased from BrewPi. I had a Raspberry Pi 3 around that wasn't doing anything.

Once you have the software running, shutdown and power off the Raspberry Pi and power off the BrewPi to be ready for the next step!

Part 4: Build the BrewPi Panel

With all of the parts (two SSR's, BrewPi, RasPi, power strip) and wiring involved, I decided to build a wood panel to keep everything nice and orderly (or attempt to).

I decided to use a 24" long by 20" high piece of 1/2" plywood for the panel. I sanded and painted it with the same paint I had on the walls.

I started with a test layout on my bench to get a sense for how the wires would run around. Then I used OmniGraffle to build a diagram of how the panel would be laid out. This was also a handy reference for me to follow when building the panel. I've provided the diagram in the gallery below.

From the Parts List above, this is #2,3,4,5,6,10,11,15,23,26,27

Okay, let's do this!

Pictures from part 4 of the build

Part 5: Connect Freezer to the BrewPi Panel

This step uses parts 7,9,19

Pictures from part 5 of the build

(Optional) Part 6: Attach Foam Insulation

This step is optional. I got part of the way through this and decided to remove the foam and go without.

Pictures from part 6 of the build

Part 7: Cleaning and Final Assembly

Pictures from part 7 of the build