Friday, December 23, 2016

refrigerator 4

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I have been keeping a spreadsheet on my old refrigerator, charting the percent of time it operates against the temperature of the air in the kitchen.

I am glad now that I got this data during the summer since the furnace now obscures the signature of the refrigerator and freezer. I wrote about the fridge here, here and then here.

The slope of the line shows that as the temperature around the fridge rises, more electricity is used to keep the inside of the fridge at the set point. I have not varied the settings of the fridge since the second article where I noted that I had switched on the door strip heater by mistake.

For every data point I made a measurement over several hours using my smart meter data. Usually the measurements were in the early morning after the appliance had been undisturbed for at least eight hours. This is the measurement for the Oct 11 data. A screen capture of the Blueline Energy Cloud software in my browser taken into a drawing program (CorelDraw) to add the measurements.

And finally a bit of calculation to turn the centimeter distances into time and to calculate the average time of a number of cycles and the percentage of total time the fridge is running at that temperature.

Since the fridge always uses the same amount of power when it runs, 150 watts, I decided to track the Duty Cycle, or the % of the time the fridge operates. That way I can predict, at a given temperature, how much the fridge will use as a minimum. It may use more than this if I open the door often or fill it with warm food.

I have been turning the fridge off during my peak period and coasting through as much as six hours with no bad effects (spoiled food). I did add a bit more insulation to the outside of the freezer compartment but otherwise the fridge is an old 1994 model.

Thanks for your interest,

George Plhak
Lion's Head, Ontario, Canada

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