Ultra Efficient Fridge Project

keezer_finishedHaving more time to think has allowed me to realize how distracting our possessions can be. A few weeks ago, I sold my moped which had been with me since high school. For both myself and Mrs. CK, it was a catalyst to a selling spree. I have especially been working on clearing out larger items that are taking up a lot of space. One of these items was an old second-hand chest freezer.Ā  We had used if for storing meat at one point, as a chest fridge for home-brewing more recently, then it sat idle. Chest freezers are designed for optimal efficiency, so I decided to clean it up and compare it against my Energy Star kegerator. The losing appliance would be listed and sold on Craigslist.

When I first started brewing beer, we decided for some reason that we would supply 100% of our beer consumption. It was like a new year’s resolution we suddenly made up even though it was November. Not only would we brew all the beer that we were drinking, but also all the beer we would serve guests in our home. Essentially, there was a ban on purchasing commercially produced alcohol, and being a couple of weirdos, we stuck with it. We brewed 48 batches of beer over the course of a year, and quickly neared the legal limit for home-brewing.

homebrew_selection

Who needs this many home-made beers on tap?

In my post about early retirement and the FI lifestyle, I talk about hobbies. One of the main rules I lay down for venturing into a new hobby is: don’t go crazy buying tons of superfluous crap. Well, I learned a lot about making beer in that year, but I also broke the rules and acquired too much equipment. There were a few parties where I had 5 craft beers on tap. In addition to the chest freezer, we had 2 kegerators converted to hold double taps each. While it made for some awesome parties, keeping 2 IPAs, a stout, a belgian ale, and a saison on tap is ridiculous – even if it does put a smile on my face thinking about it šŸ™‚

Brewing that much beer was too much to maintain, and after the first year, I started slowing down. Before I quit my job at the beginning of this summer, I sold one of the kegerators. That left me with 2 options for keeping my home-brewed kegs. Up to this point, the ugly, rusted chest freezer stayed in the garage. Because of its age and condition, I would probably be lucky to get $50 selling it as-is. But before I could even consider swapping it out with the kegerator, the chest freezer was going to need some beautification. Inspired by a beach side bar in Barbados that also used a chest fridge, I decided to paint it Caribbean blue.

keezer_before

Ugly, rusted chest freezer.

I stripped down the chest freezer, removed the handles and insulation on the lid, cleaned the surfaces with alcohol, and taped up the lower portion. After spraying it down with two $5 cans of spray paint, I was left with a nice glossy coat. Spray paint takes a long time to dry, but I painted it just before our trip to Nova Scotia, so it had 2 weeks to dry in the Prius’s garage spot. When we returned from our trip, I put it all back together and moved it into the house for testing.

keezer_painting

Looking more presentable.

How to Convert a Chest Freezer to a Keezer

Obviously, the chest freezer is designed to operate at much colder temperatures than the temperature at which we keep our beer. When I originally started using it as a chest fridge/keezer, I went the cheap route and hacked the existing thermostat. On a typical mechanical fridge/freezer thermostat, there is a screw for factory adjustments. By fiddling with this adjustment screw, I was able to get the temperature to stay in a decent range for keeping beer. I had used it like this in my garage, but only for a couple of parties.

When I brought the chest fridge into the house for more testing, I realized that hacking the old thermostat was not the best idea. It was not optimized for operating in a temperature range above freezing. I had not noticed before, but the temperature was fluctuating wildly and the compressor was short cycling. This was not an acceptable solution, so I decided to install a new thermostat.

There are thermostats that you can simply plug the chest freezer into, then run a small thermometer lead inside to measure the temperature. The thermostat turns the power on and off to keep the freezer at a desired temperature – it simply overrides the factory thermostat. This is the easiest way, and at the time of writing this article, a plug-in thermostat costs only $35. But if you can do some electrical wiring, a basic digital temperature controller costs even less at $15.

I went with the cheaper, and a bit cleaner, option of installing a basic controller and taking the old thermostat out of the loop. The controller came with basic wiring instructions – splice an extra wire from the power cord to power the controller, and hook up the digital controller switch to the same wires that ran from the original thermostat to the compressor. I first powered on the controller without hooking up the compressor so I could adjust all the settings. I set the controller to the cooling mode, adjusted the compressor short cycle protection to 8 min, and set the temp differential to 3 degrees – this determines how much the temperature can rise before the compressor is turned on. I then set the desired temp to 34 degrees and hooked up the compressor. It worked flawlessly.

keezer_temperature_controller

Installed digital temperature controller.

The chest fridge was now looking sharp and running perfectly. It was time to determine whether to sell the kegerator or the chest fridge. I knew the kegerator would sell for more, but it was also an Energy Star appliance. The chest fridge on the other hand is probably 20 years old – it might even be older than the Energy Star rating system. But there are some benefits in the chest fridge design. The kegerator dissipates heat from the two sides, whereas the chest fridge has no front door and dissipates heat from the two sides and the large front area.Ā  More surface area to dissipate heat should mean more efficiency. The chest fridge also has better insulation and a top door so that cold air does not pour out when it’s opened.

Energy Consumption: Kegerator vs. Keezer

While I was working on the build, I plugged the kegerator into my energy meter. To account for fluctuations between adding and removing beer, I let the meter run for a month. When the chest fridge build was ready, I swapped fridges and again ran the energy meter for a month. I did the cost analysis with CT electricity rate which is close to 25 cents per kilowatt-hour for 100% renewable energy, and the results were pretty shocking…

Energy Star Kegerator:

28.3 kWh/month * .25 cents/kWh = $7.08 /month

Old Chest Freezer Converted to Fridge:

10.2 kWh/month * .25 cents/kWh = $2.55 /month

So for $10 worth of spray paint and a $15 digital temperature controller, I was able to turn an ancient, worthless chest freezer into a fridge that is nearly three times as efficient as an Energy Star fridge. The kegerator is officially going up on Craigslist.

keezer_comparison

The converted chest fridge also has more capacity, and with a digital thermostat it can become a freezer again with the touch of a button. Not only is it useful for beer, but also for cold storage of our garden vegetables. In addition to 2 kegs, I also store loads of cabbages and carrots from the garden. The only drawback is that chest freezers are not built to handle condensation. After a month or so, depending on usage and humidity, a pool of water can build up inside. This is not a big deal, I just wipe it down when I replace a keg. By selling the 2 kegerators, I’ll have another ~$1000 back in my pocket, a cleared out garage, a cleared out mind, and can still indulge in my hobby while using much less energy.

16 thoughts on “Ultra Efficient Fridge Project

  1. Wow! That’s unbelievable! Who would’ve though the chest freezer would win that contest?! Makes me think I need to get an energy meter to test out some of our appliances…

    By the way, that’s a stunning paint job on the freezer!

  2. Wowza, I’m quite impressed by your beer production. I’m sure Mr. Picky Pincher would be thrilled to have gallons and gallons of beer on hand. šŸ™‚ (Also, I’m craving a Belgian ale now, aghh)

    I’ve never thought to paint a freezer; I really like that color!

    I am BAFFLED at how more energy efficient the old chest freezer is when compared to an Energy Star appliance. It’s making me question our Energy Star purchases…

    We also got a giant reach-in freezer and we’re loving it already! It means we’ll be able to start batch cooking and stockpiling food for maximum savings!

    • I had a feeling that the chest fridge would win out, but I was pretty surprised myself when I saw by how much.

      It’s been a while since I did a Belgian ale, maybe one of the next brews šŸ™‚

  3. Mr. CK, you do the coolest stuff!

    Just awesome, and I love the line about the old chest freezer being older than the Energy Star system. Classic and cool (!) and a heckuvalot cheaper… wins all around. Let’s drink to that!!

    Cheers, and thanks as always for a really fun read. (Also, I had no idea there was a home brewing production limit. I mean, I guess that makes sense. But I can’t believe you’re bumping up against it.)

  4. Let’s count the ways in which I found this post pleasing:

    1. The number of beers you kept on tap made me happy
    2. The colour you chose to paint your freezer
    3. The hacking of the thermostat
    4. The underdog winning the competition

    Nice job!

  5. Man, I’d really like to see a tour/explanation/how-to’s on your brewing. I spend entirely too much money on beer every month. Keep up the good work!

    • Brewing is a lot of work, but also a lot of fun, and you can make excellent beer pretty cheap. I am trying to pull together some material to make a couple of posts, but have a few more experiments I want to run out first.

      Thanks for the great feedback, and cheers!

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