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Fermentation Chamber - Converting an old freezer into a temperature controlled fermentation chamber


I've been wanting to do this for a long time, but really didn't have the time until recently.  I had an old, working freezer that wasn't in use, and my conical fermenter fit inside of it perfectly.  

In the past, my brewing was limited to ales that I could ferment inside my house in carboys...but last year I got a 13 gallon conical fermenter, and moving it full of beer from the garage to the house was a major challenge.  We had an upright freezer that wasn't in use, and I thought this would be perfect for controlling the temperature of fermentation.  The project only took a few hours and turned out far better than I anticipated.  I'm fermenting my first lager with it now, and it seems to be going exactly as I had hoped.

Project Materials:
 - One working Freezer
 - STC1000 or equivalent temperature controller
 - 2 Halogen lights (incandescent would work as well here - I liked the price and form factor of the halogen lights I used.  LED is NOT a good choice here - this light needs to generate heat).
 - 15 foot, 14 gauge or higher extension cord
 - crimp connectors for 14 gauge wire
 - Plastic retrofit box with duplex receptacle
 - Velcro with adhesive
 - Clear silicone adhesive

Goals:
 - Make as few modifications to the freezer as possible - specifically, I didn't want to cut the electrical cord to the freezer.  I did that for my keezer and the wiring got messy.
 - Make sure that I don't drill through any of the coils...that makes the freezer useless...

The project:

The freezer I used had a sheet metal shield over the refrigeration coils.  I removed it knowing that I wanted to drill a hole for the temperature sensor and power to the halogen lamps I was going to use to heat the freezer (for ales in the winter).  When I removed the shield it was pretty clear what I needed to do.


You can see in the upper right hand part of the picture that there was a plastic panel where the wiring came through.  I measured the outside to figure out how thick the wall was behind the plastic cut-out and seeing that is was ~1" I was confident that it was safe to drill a hole.  I drilled a 1/2" hole through plastic, styrofoam and sheet metal on the back of the freezer.  Just enough to thread the power cable and sensor wire through.

My conical fermenter came with a thermowell, and I had a plastic fitting with 1/2" NPT fittings that matched the thermowell.  I stuck the sensor wire into the fitting and put some silicone in the fitting to hold it in place.

Picture
The next challenge was wiring.  The STC1000 is pretty simple, but I did have to think about how to make it work.  I designated the top receptacle for the heating circuit and the bottom for the cooling circuit.  In the wiring diagram below I used a non-conventional color - the wire shown as red should in fact be white (neutral), but a white wire is hard to see on a white background, so ignore convention in this diagram.  I'm using the relay circuits on the STC1000 to switch the hot side.  

One note - in order to separate the receptacles so they can be turned on independently, I had to cut the brass line on the hot side so that the STC1000 could turn on heat and cool independently.  On the neutral side, I left the connection intact since it simplified the wiring for me.

Picture
Picture
That is really the bulk of the project.  Everything else was just finish work.  
 - I did put a piece of wood on the bottom of the freezer to protect it from getting scratched by the legs of the fermenter.
 - I used velcro to stick the halogen light on the side of the freezer.
 - I used velcro to put the J-Box on the side of the freezer.
 - I used velcro to put the STC1000 on top of the freezer next to the J-Box to minimize wiring.
 - I put the conical fermenter in and screwed the plastic fitting with the temperature probe into the thermowell.
 - I used an empty tennis ball can filled with water for my airlock.
​

It is true that the STC1000 only measures temperature in Celsius.  For me that was a minor consideration, I understand the conversion, and the price more than justified the minor inconvenience for me.  All roads lead to better beer!  I have high expectations for my first lager.
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