05 July 2010

Freezer as Fridge, Revision 2.0

This post is a belated response to a question from Chile, over at Chile Chews, about our freezer to fridge conversion.

Many folks trying to reduce energy usage (for running on solar power, or just to be more responsible) have used a chest freezer converted to a fridge via external thermostat.

We used ours for four years, and it did work well - however, getting food out of the bottom was always a challenge, and the moisture that gathered in the bottom was a hassle to deal with as well (a centimeter or so would collect every few weeks, and it had to be sopped up with a towel ... after gucking up a bunch of stuff that was in there). Plus, it was a bit small for our family (which grew by one adult and 2 kids when the Reluctant Farmer and I got married).

What we ended up with is a bit of a compromise: we have an upright freezer, the kind that looks like a fridge, and are using the same thermostat widget on it. The ice forms on the top shelf, and moisture that drips down is easily wiped out by just pulling out the bottom drawer and swiping a towel along the base. Everything is easy to reach, and we even have door shelves for the mustard and pickles, yay! I missed those.

Power consumption according to the Kill-a-watt meter is 6.12 kWH over 351 hours ... which is, 6120 watt-hours/351 hours = 17.4 watts, or 418 watt-hours per day. If you work it out for the year its (0.418 KWH/day)(365 days) = 153 kWH per year. An energy star fridge (no freezer) of about the same size is listed at around 315 kWH/yr.

Half the power consumption is good. :)

Now, for a comparison from the old chest freezer/fridge to the new one:

The old freezer was a Kenmore 7.2 cu ft plain jane chest freezer, rated at 279 kWh/yr used as a freezer.
Used as a fridge, it needed 1 kW over 79 hours, which would be 1000 watt-hours/79 hours = 12.65 watts, or 303 watt-hours per day.

The new one is also a Kenmore, but bigger: it's 13.7 cubic feet, so almost double the size, and rated at 442 kwh/year used as a freezer.
Used as a fridge, at 6.12 kWH over 351 hours, we got 17.4 watts/hour, or 418 watt-hours per day.

So yes, overall usage went up … but on a per cubic foot basis:
Old freezer: 12.7/7.2 = 1.8 watts/hr/cubic foot
New freezer: 17.4/13.7 = 1.3 watts/hr/cubic foot

1 comment:

  1. flannelberry3:49 pm

    That is such a great idea. We used to have an icebox when we lived on our boat -things were very simple then! I think we'll replace the fridge with an upright freezer when it dies...


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