Convert a Chest Freezer to Kegerator or Fermenter for $20




Introduction: Convert a Chest Freezer to Kegerator or Fermenter for $20

About: I'm a PhD candidate in Pharmaceutical Sciences living the dream with my wife, two dogs, and a basement that overfloweth with homebrew.

So there's a couple other instructables already about converting a chest freezer to a kegerator (aka keezer), but most of them use the expensive plug and play temperature controllers.  If you're willing to get your hands a little dirty, cheap controllers to hardwire in can be found on eBay for ~$20.  Not only do you get a nice digital readout with the current temperature and the ability to set to specific temperatures, you also have the option of adding a heat source as well to turn the freezer into a temperature controlled fermenter.

Temperature controller:
I purchased mine for $20 (Link removed due to seller jacking price up $100).  eBay links don't last forever, but you can search for "digital temperature controller 110V."  Many of them are designed to run on 220V, so make sure you get the proper voltage controller (110V in the US).  This particular one allows for many customized settings include compressor delay, which is important as rapid on/off cycling can kill the compressor.

Tools needed:
Dremel/rotary tool or jigsaw
Wire cutters
Multimeter (recommended)

Misc parts:
Wire nut
Electrical tape
Extra power cord

Step 1: Preparing the Freezer

Foreword:  You need to be very careful about cutting through the walls of the freezer as most of the walls contain the cooling element.  If you puncture a cooling element, all the coolant will leak out and you'll be left with a fancy box.  In my freezer, the was an area in the bottom right side that contained the compressor, enough room to install the controller, and a thin wall obviously devoid of any cooling parts.

Measure the size hole you need to cut and trace it out on the wall.  Double check you're not drilling through the thick part.  Drill a hole in each corner and cut between them with either a dremel tool or jigsaw.  If using a jigsaw, make sure the blade won't poke through far enough to hit and of the compressor lines.  Make sure the controller will fit in the hole you cut.

An alternative to mounting the controller on the freeser is to use a plastic junction box and put the controller in the middle of the existing power cord.  A blank faceplate provides a suitable surface to mount the controller.  The finished results may not be as neat, but it gets the job done.

Step 2: Wiring in the Controller

The first thing is to cut the plug end from the existing cable (unless you're using the junction box, then cut somewhere in between).  It's important to note which line is the hot and which is the neutral.  The ground is usually smaller and pretty easy to identify.  After cutting the cable, the wiring schematic shows the hot going to the thermostat which is in the panel I pulled out.  I looked for the wire coming in from the power supply and after disconnecting it from thermostat, tested for continuity with the multimeter.  Since the end connected to the thermostat is the hot, you should get no resistance on the other end of that same wire.  Mark it with electrical tape or black marker.

The way the temperature controller work is by cutting on and off the flow from the hot to either a heating or cooling element.  Both circuits are normally open.  When the temperature gets too hot, it will close the circuit and allow electricity to flow to the cooling element (the freezer).  If I was using the freezer as a fermenter I might also have a heating element like a small ceramic heater or dehydrator connected that would be turned on when the temperature dropped too much.

To wire it up, the incoming (black cord in my case) hot and neutral get connected to the appropriate posts.  Here the hot went to post 5 and the neutral to post 6, as shown on the diagram.  The hot also needs to be connected to the post to switching portion before reaching the heating/cooling elements.  Because post 1 and 5 both need to be connected to the incoming hot, you need to either pigtail a split in or do what I did an jumper a second short wire between the two.  Next you need to connect the outgoing post shown going to the cooling element to the line that goes to the freezer (white cord here).  Although the diagram shown this to be post 2, I found this to be a misprint and that post 3 actually is for the cooling element.  Initially the freezer came on when the temperature was too low, which could have had disastrous implications if I didn't catch the mistake.  Post 7 and 8 get connected to the included temperature probe, it doesn't matter which leg connects to which post.  The neutral going to the freezer should get attached to post 6 along with the neutral coming from the outlet. The grounds don't actually connect to the controller and should be joined directly to each other.

Before sealing everything up, plug in the freezer to make sure it is all working as intended.  To set the temperature, press set, use the up/down arrows to select the temp, then press reset.  Test both when the probe it too hot or too cold.  You can hold it against an ice cube if you need to cool it down.

Step 3: Finishing Up

Run the probe up the back of the freezer and snake it under the lid.  Duct taping it to the freezer is a good way to keep the cables managed.  Fit the controller through the hole and use the orange clips to hold it against the wall.  They can be a little tricky to get on, but keep at it.  My controller operates in Celsius, so fridge temp is 4 degrees.  If yours is in Fahrenheit you probably want to set it to 39 or so.  This particular freezer was tall enough to kit kegs and carboys right off the bat, but I'll be installing a wooden collar and faucets as detailed in other instructables soon.  In the mean time a picnic tap will get the job done.  Good luck and happy brewing!



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38 Discussions

Cool 'structable, I caught the link before the seller got greedy (or woke up, whichever may actually apply) so I have my $20 controller in hand, now searching Craigslist for freezers. I think I'll mount it in a box on top though for easier access. BTW your brew setup looks identical to mine.

I'm thinking about putting the whole shebang in the basement under the kitchen and running a tap up through the wall to the kitchen sink's vegetable sprayer cutout, but the tap hose would have to be about 12' long, not sure if that would cause problems.

4 replies

The problem with that setup is that the beer in the lines between the sink and freezer will get warm. You would have to add something to keep the lines cold. There's a nice post about one guys solution on homebrewtalk in the form of a DIY line chiller that pumps cool water to the sink and back.

Hmmmm...not sure I'd want to have a pump running continuously just to keep a hose cool...maybe I could rig a check valve so as to let the line drain back into the keg...gotta think about it. Thanks

run the hose upstairs inside a 2"pvc pipe filled with expandable insulation.that should keep it pretty cool.

dont forget you're going to want to clean the line every once in a while, so a permanent line is going to be more maintenance. as well as requring quite a bit of co2 pressure to pump liquid to a upstairs location. so you're going to be spending $ on a larger co2 tank as getting it filled more often.. just build a nice keezer and walk downstairs to get a beer..

Just curious, how many years are people getting from their kegerator?
I used the external plug and play device and have mine ready to go. I
plan to use this as a fridge and beer cooler, but only if it's the most
economical way to do do so.

I did mine many years ago during my Lagering phase. The freezer eventually failed. since then I have been using an all fridge where no electronics are needed. Oh, I keep my hops in an actual freezer. I never leave my kegs attached to the C02, as I find it totally unnecessary as I never put more that 16 litres into a 19 litre keg (I do 30+l batches). I really enjoyed your instructable. Prost, skál, sláinte, lloniannau, cheers

I like this! I made a chest freezer kegorator using a thermostat from a from an old fridge but after about a year that broke now I need to do this! But also replace all my hoses and pretty much everything else... Oh well, loved the instructable and look forward to fixing mine!

I found one for under $17.00...

Also installing 2 computer fans, one on each side one blowing down the other up will circulate the are and eliminate any warm zones...

My 7.1 cu ft chest freezer ( draws 12.1 amps on start up. The STC 1000 is only supposed to carry 10amps, does any one worry about this much?

That's cool, but wow long did it take to do everything?

February 2015: When I first did this in the UK many years ago, it cost me a fortune. Skeptical at how cheap these are, I followed your advice and searched ebay for a "digital temperature controller 110V.", I found a few to choose from and was able to pick one up for under $15 including shipping from china. I am not sure if it is an updated model of the one pictured in article but the controller is a single relay type that can be programed to either heat or cool to a set temperature that you choose, so in short it’s ideal for a number of projects requiring heating or cooling. Rather than cutting holes into a Freezer to mount the controller I would personally recommend wiring the controller to switch an electrical socket on and off and simply plug the freezer into this socket. The temperature probe should be ok if left hanging over the wall inside the freezer with the door closed. THANK’S for an inspiring article.

I've seen this done on many homebrew sites to control fermenting temps and for kegerators. I use a Johnson Controller that sits between the power plug and wall. The only problem is that the temps lead to condensation and mold. Between every beer I ferment I have to clean it. I am not sure how you would control this in a kegerator setup without cleaning it out every two weeks.

2 replies

Get an Eva-Dry wireless dehumidifier like this:

If you're having problem with mold and condensation, try putting some desiccant in there. DampRid is one option.  This will absorb the extra moisture which should cut down the mold too.

Back when i made my keezer from the Johnson controller, i noticed the placement of the thermocouple inside the chest was important. The bottom was cold, the top was hotter. I put a spare 12volt 5 inch dia. computer cooling fan i had in the chest and the entire inside of the chest had a uniform temperature. I run this all the time because i keep bottles as well as corny keg in all the spare spaces. See attached photo.


Thanks for the nice plan! Can this type of rig facilitate brewing lagers up around the 70F, then descending temp control in about 2 deg/day increments?

Whereabouts did you set the controller to not come on and off rapidly to avoid burning out the compressor? Thanks.

On there controller's output, I noticed it says 220V. My compressor says it operates on 110/120V and I noticed the one in the picture does to. How is that okay?

1 reply

Think of the output rating as up to. It operates as an on off switch so if you are feeding 110V in, you will only get 110V out when it is 'on.' The input voltage is important because that needs to run the electronics in the circuit and is designed to work at a particular voltage.