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AC_Hacker · 05-15-13, 01:38 AM

I switched over from my Teensy thermostat to the Chinese model I bought on ebay, and the inscrutable thermostat works just great!

Here is a log of operation:

The new thermostat works just fine. I have the hysteresis set to minimum (1) and the temp swings are as you see above.

I did a previous run, then adjusted the temperature set point up one degree, to 3 degrees C which would be 37.4 degrees F.

Previously, the lower swing got too close to freezing, which can be rough on produce, so now the adjustment is about right.

The temperature swings with the Teensy thermostat were smaller, and the compressor kicked on more frequently. I'll do a power calculation after a couple of days of running to see if there is any change in power use.

* * *

My goal was to see if an upright freezer, when converted to refrigerator duty, had any appreciable power savings over a comparable refrigerator. My tests indicate that the converted freezer will use roughly half the power of a comparably sized refrigerator. In this case, I used a rather unspectacular freezer candidate (NOT Energy Star), and it is performing much better than the same-sized Energy Star refrigerators. I would expect that if I had started with an Energy Star Freezer, the resulting Freezerator would have performed even better.

Doing this conversion with a cheap Chinese thermostat is really easy.

Now that I have some modest experience with Teensy/Arduino, making my own thermostat was really easy, too.

So, all in all, this has been a very successful project.

Best,

-AC_Hacker

05-15-13, 01:38 AM	#11
AC_Hacker Supreme EcoRenovator Join Date: Mar 2009 Location: Portland, OR Posts: 4,004 Thanks: 303 Thanked 723 Times in 534 Posts	The Inscrutable Thermostat works just great! I switched over from my Teensy thermostat to the Chinese model I bought on ebay, and the inscrutable thermostat works just great! Here is a log of operation: The new thermostat works just fine. I have the hysteresis set to minimum (1) and the temp swings are as you see above. I did a previous run, then adjusted the temperature set point up one degree, to 3 degrees C which would be 37.4 degrees F. Previously, the lower swing got too close to freezing, which can be rough on produce, so now the adjustment is about right. The temperature swings with the Teensy thermostat were smaller, and the compressor kicked on more frequently. I'll do a power calculation after a couple of days of running to see if there is any change in power use. * * * My goal was to see if an upright freezer, when converted to refrigerator duty, had any appreciable power savings over a comparable refrigerator. My tests indicate that the converted freezer will use roughly half the power of a comparably sized refrigerator. In this case, I used a rather unspectacular freezer candidate (NOT Energy Star), and it is performing much better than the same-sized Energy Star refrigerators. I would expect that if I had started with an Energy Star Freezer, the resulting Freezerator would have performed even better. Doing this conversion with a cheap Chinese thermostat is really easy. Now that I have some modest experience with Teensy/Arduino, making my own thermostat was really easy, too. So, all in all, this has been a very successful project. Best, -AC_Hacker Attached Images __________________ I'm not an HVAC technician. In fact, I'm barely even a hacker...