Freezer Fermentation Chamber Project
Update April 2020
I've built a second fermentation chamber and I made a few tweaks to the design
- Change #1: I was running out of room on the power strip, so I got a big 9-outlet power strip with plenty of spacing between plugs to fit AC/DC adapters Amazon link
- Change #2: I realized that I didn't need to cut the power cord to the freezer. I had some of these short extension cords Amazon link that I used instead. I cut the short extension cord and soldered my wires into that. The freezer just plugs into the end of the extension cord. Nice!
- Change #3: This was more for asthetics, but I used a lot more zip ties to keep the wiring neat.
Pictures of the April 2020 changes
Update January 2020
I've made a few changes to the fermentation chamber after using it for the last 11 months.
- Problem #1: I found that the RJ11 inline connections on the collar of the chamber were corroding due to the moisture inside the chamber.
- Solution #1: I moved the RJ11 OneWire connections outside of the chamber. I also elected to not seal up the hole in the collar with silicone sealant. This will give me the flexibility to change out temperature connections in the future without a lot of hassle. I used some leftover reflectix insulation (could also use foam) and some foil tape to close up the air gaps.
- Problem #2: I found that the position of the fan and the bulky ABS pipe was not ideal. The wire for the fan kept getting in the way and the placement of the fan made it difficult to place the carboy into the chamber.
- Solution #2: I removed the 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.
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
- Magic Chef 7 cu. ft. chest freezer (model HMCF7W3)
- BrewPi Spark 3
- Rasbperry Pi 3 Model B
- 10A Solid State Relay
- 40A Solid State Relay
- SSR Heat Sink
- Onewire Temperature Sensor (2)
- Wall mounted onewire temperature sensor (for the fermentor bucket)
- Brewer's Edge Space Heater from William's Brewing
- Red and black 18 AWG electrical wire
- 18 AWG ring terminals
- 16" stainless steel thermowell from Brewers Hardware
- Two hole rubber stopper (to fit the thermowell and airlock on the glass carboy)
- Corsair ML120, 120mm Premium Magnetic Levitation Fan (2-Pack) Amazon link
- DC Power supply for 3 or 4-pin 12V PC case fans Amazon link
- NOT NEEDED ANYMORE: Various 4" and 3" ABS couplings and 3" ABS pipe for the fan ducting (detailed list below)
- NOT NEEDED ANYMORE: ABS pipe cement
- 2 x RJ12/RJ11 Straight telephone inline coupler Amazon link
- 2 x 3 foot RJ12 cables Amazon link
- 3/4" x 2' x 4' Birch Plywood
- 1" x 4" x 8' and 1" x 4" x 6' Hemlock Boards
- Pink rigid insulating foam (optional)
- Screws/staples/glue/tape for attaching the plywood, hemlock, and foam
- Spray Polyurethane, water based, semi-gloss
- Construction adhesive
- Three colors of 14AWG wire
- 1/2" x 2' x 4' Birch Plywood
- Two door hinges (4 inch x 3 3/20 inch Tee Hinge) Home Depot link
- Small screws, nuts to attach the PC fan to the hinge. I used M4 x 35mm bolts and M4 hex nuts.
- 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.
- Start with the process of applying many coats of polyurethane to the hemlock boards. Depending on how smooth you want the finish to be, this could take a few days of paining and sanding and painting again. I think I was happy with the results after 6 coats (note to self, next time, give the boards a good sanding with 220 grit sandpaper before starting!). I made sure to use painters tape on one edge so that I would get a good bond with the construction adhesive.
- While you're doing the previous step, you can build the inner collar with plywood.
- Once you're satisfied with the polyurethane on the hemlock boards, cut those and attach them to the plywood collar. I used wood glue and brads in a staple gun.
- If you haven't done so already, remove the freezer lid from the freezer. Watch out for the spring loaded hinges.
- My freezer has a light on the inside of the lid. Thankfully, there is a easy disconnect for the wiring on the back of the freezer. I'll cut those wires and extend them so that I can reconnect the light
- Place the collar on the freezer and note where the hinges need to connect on the collar in the back.
- Mark where you want your holes located on the collar and drill them. I went with a few inches to the right of the left hinge. You'll need two holes, one for the beer and freezer sensors, and a second hole for power to the heating pad, power to the PC fan.
- Use the construction adhesive to attach the collar to the top of the freezer. Put the freezer lid on top of the collar and put some weight on top of it (a couple of 6 gallon fermenting buckets full of water should do it)
- Give it 24 hours for the adhesive to fully cure before fiddling with it
- Re-attach the hinges for the freezer lid to the wood collar
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!
- Start with placing all of the hardware on the panel (2 x SSR's, BrewPi, RasPi, Power Strip). I started in the bottom left corner with the 10A SSR for the heater, then the heatsink for the 40A SSR for the fridge (probably could have gone with a 10A and no heatsink for the fridge, but I decided to over engineer it). I had to go to a local hardware store to get screws to mount the 40A SSR to the heatsink (no screws included in the package from BrewPi).
- Use some Velcro tape to stick the BrewPi to the panel. There were some screws included, but they were too small.
- Next is the Raspberry Pi. Use small #6 x 1" screws on the back of the plastic case. Yes, these are too long with the 1/2" plywood. I used a Dremel at the end to trim off all the long screws from the back of the plywood.
- Put the power strip up in the upper left.
- Run the USB connection between the BrewPi and Raspberry Pi, the power for the BrewPi and Raspberry Pi and power for the fan.
- You can use blue painters tape to keep the wires in place until I was happy with their location. Then I used a combination of cable clips and zip-tie mounts to secure them in place.
- Run the control wires between the BrewPi actuator sockets and the SSR's
- The heating pad was a simple two wire (hot and neutral) cord. Cut the cord 4" from the plug and used some 14" AWG wire that I had on hand. I have a soldering iron, so I soldered the wires together for a good connection and used heat shrink tubing over it. I used a long length of wire going off the panel.
- The freezer power cord was a three wire (hot, neutral, ground) cord. Cut that as well and soldered in 14AWG wire with heat shrink tubing (with long wires as well).
- Connect the hot wire from the heater to the 10A SSR
- Connect the hot wire from the freezer to the 10A SSR
- Tidy up all the wires on the panel with cable clips, zip ties, zip-tie mounts
- Mount the panel up on the wall behind the freezer. I kept it so the BrewPi screen was at about eye level for me. Don't put it up too high, you risk the cables not being long enough to reach the freezer
- Depending on your network, run a ethernet patch cord to your Raspberry Pi.
Pictures from part 4 of the build
Part 5: Connect Freezer to the BrewPi Panel
This step uses parts 7,9,19
- Connect the wires from the panel for the freezer to the end of the freezer power cord that you cut. I used my soldering iron and some heat shrink tubing, but you can connect them how you like.
- Put the heating pad inside the freezer and run the power cord through one of the holes. I did not secure the heating pad in place yet. Connect the wires from the panel for the heater to your cut heater pad cord
- Connect the RJ12 cables to the BrewPi and to the RJ12 jacks on the outside of the wood collar.
- Connect the Onewire temperature sensors to the RJ12 jacks on the outside of the wood collar.
- Use a eye hook on the wood collar to cable tie the freezer temperature sensor to
- Now is the big moment, you can flip the switch on the power strip on the panel and turn everything on.
- Make sure the BrewPi sees the two temperature sensors and make sure you can reach the BrewPi software website on the Raspberry Pi.
- Use the touch screen on the BrewPi to turn on the freezer and heater to make sure they work
- You're almost there! Go ahead and power everything off for now.
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.
- Measure the height of your wood collar and subtract about 1/2 a inch. Cut enough strips of foam to go around the inside of the wood collar. The reason for subtracting a 1/2 a inch is that the inside of the freezer lid may have protrusion that may hit your foam if it's the full height.
- You could use a adhesive that specifically works with foam board, but in my case it didn't work so well. Locktite PL 300 is one of those, but it did not work well for me. I clamped the foam onto the wood frame and after 24 hours, I could slide the foam off.
- Another option would be to use some screws to attach the foam.
Pictures from part 6 of the build
Part 7: Cleaning and Final Assembly
- If you're repurposing a used freezer, you should give the insides a good cleaning if you haven't already done so. Since my freezer is new, I made sure to remove all the dust and debris from the inside and give it a decent wipe down with a wet cloth. Then I used some Star San in a spray bottle to sanitize the inside. I wiped everything up so that it was dry.
- Next is to put the fan and fan duct in place and secure it with cable ties.
- Connect the power cord from the fan and use silicone sealant to close up the hole through the wood collar.
- Attach the heating pad to the side of the freezer wall. I placed it in the bottom third of the wall. Use silicone sealant to close up the hole in the wood collar for the heater power cord.
- For my fermentation bucket, I'm using a wall-mounted temperature sensor (part #8). I used a hole saw drill bit to cut a hole in my bucket and cleaned up the hole with a box cutter blade. Then I attached the temperature sensor to the side of the bucket and used some wrenches to tighten it. I filled the bucket with water and let it sit in a sink for a while to make sure it would not leak.
- Connect the two Onewire temperature probes.
- You're all done! Start making some beer!
Pictures from part 7 of the build