Controller for freezer?

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flugelizor

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If you are a penny pincher like me, you may have wondered why do you need a controller for the freezer for your keezer? If you could just set it high enough it would work.

I logged the temperature of my brand new unmodified GE 7.0 freezer.
I found temperature swings of 15 degrees constantly:
freezerlog-62737.jpg
 
^ lol right?
So you're saying if I keep my freezer on low setting, I can maintain good serving temps without needing a controller?
 
^ lol right?
So you're saying if I keep my freezer on low setting, I can maintain good serving temps without needing a controller?
 
Sorry, I thought it was self explanatory.
I dashed this message off in a hurry before work.

In my opinion those kinds of temperature swings will not be acceptable for a keezer.
So maybe this chart will save someone some time.
Instead of fiddling with modifying their existing controller they will just buy a good one.

One issue is that it was empty. A working keezer would have more thermal mass, so maybe the temperature swings will be smaller?
 
I've used the same logger at work and seen similar graphs.

Keep in mind that the controller will only get you so far. The up swings in temperature are based on the insulation and the thermal thermal mass inside. The down swings are the cooling cycle. Your graph will look different depending on where your controller probe is located and where the logger is located. I'm assuming you're using an EasyLogUSB from ThermoWorks or directly from Lascar. These will only monitor air temperature in you freezer/fridge, so likely even with the controller probe attached to thermal mass, the spikes on your logger graph will be just as sharp unless you have some airflow.

Using a programmable controller will get you narrower swings, i.e. lower highs, and higher lows, but you have to compromise that with shorter and more frequent cooling cycles which may shorten the life of the compressor.

Placing the probe in a bottle of water, or attaching it to something with more thermal mass will cause less frequent and longer cooling cycles, but it may
show up on your graph as wider swings since your logger is monitoring air temperature.

In my opinion, if you're really pinching pennies, why are you worried about temperature swings rather than efficiency? I estimated that I saved money by installing a controller on my mini fridge, because it actually runs less than stated on the tag on the back. I think the tag said average run time was 25% at a certain ambient temp, and with the controller I was getting something like 16% run time. I can read the temperature digitally on the controller, so I don't mind what the temperature swings are.
 
That's right EasyloggerUSB.
I ordered a controller:
Docooler 10A 110V Digital Temperature Controller
I will post another graph when I get it set up and full of kegs.
 
I think you'll be happy with what you can get out of it.
Here is my GE 3.1CF Minifridge with I think 1 full keg. I replaced the thermostat with the STC-1000 (I was checking accuracy, so that's why it's in °C). I believe I had it set at 3°C with a 3° swing and a 10 min delay. low of 3°C (37°F) high of 7°C (44°F).
Capture_zps249ef161.jpg
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Here is my 1949 GE 10cf fridge without a controller set at the "Normal" setting with two full kegs (which were freezing, by the way), steadier temp, but more frequent compressor cycles. One of these days I'll put a controller on that one, too.



I also have somewhere the profiles of our two stand up freezers here at work, and I was amazed at how different they were, even though they're both the same size and both have about the same amount of stuff in them, one is pretty efficient and the other is not.
 
First thing I did when I got my chest freezer was turn it on at it's warmest setting. It maintained about 20F.
 
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