# Low power usage freezer->fridge conversion



## frazzlehead (Aug 23, 2005)

We have had conversations previously about using 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 I got married, yippee!).

Anyway ... we do now have grid backup power (we used to be just solar, with gas generator backup - we built an addition to house the additional family members and got grid power at the same time, for much much less than we had expected). So, we have a bit of extra juice if we need it - we're not constrained by being fully off the grid, but still, we didn't want a big energy hog of a fridge.

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 meteris 6.12 kWH over 351 hours ... which is, if my math is right (which it may not be!), means 1.74 watts per hour. (Please tell me if I'm figuring this all out wrong - I *think* I've got my variables in the right places, but math is my weak point so I'll be grateful for help!)

For comparison:

The old freezer was a Kenmore 7.2 cu ft plain jane freezer, rated at 279 kWh/yr.
Measurements read 1 kW over 79 hours, which would be 1.27 watts/hour.

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.
At 6.12 kWH over 351 hours, we got 1.74 watts/hour.

On a per cubic foot basis:
Old freezer: 1.27/7.2 = 0.18 watts/hr/cubic foot
New freezer: 1.74/13.7 = 0.13 watts/hr/cubic foot

Which would suggest, again IF my math is right, that the new arrangement is more efficient than the old one, by about 15%.

Just tossing it out there in case the idea is of use to anyone!


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## speedfunk (Dec 7, 2005)

I read about a freezer into a a fridge conversion a while ago on the internet. Could never talk my Wife into one :lookout::lookout:

thanks for sharing your experience


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## SolarGary (Sep 8, 2005)

Hi,
I think you slipped a digit there.

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.

That seems quite good to me. Our fridge is just a bit bigger, is energy star, and its 410 KWH per year.

Gary


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## SolarGary (Sep 8, 2005)

Hi again,
Here is a nice one:
http://www.raycotechnologies.org/build_your_own_battery_powered_r.htm

Looks like it has about the same power consumption as yours.

Gary


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## frazzlehead (Aug 23, 2005)

Thanks for the math help, SolarGary! I was pretty sure I was off somewhere.  BTW I love your website, my son used some of the info in his science class last year, and we've gotten lots of ideas there too! Your climate is not much different than ours, so it's super encouraging to see what you can do.

That custom built fridge you linked to is really neat - love the wood exterior! 

One great thing about our setup - besides the low power usage - is the price tag: the freezer was about $250-300 on sale, IIRC, and the thermostat we got several years ago for under $100 (Canadian funds). I was so glad that it was a separate 'widget' - that meant that getting a totally different 'fridge' was as easy as going to Sears to see what was on sale - no need to redo any customization work. 

And, the old one is now serving as a freezer (which we needed anyway) ... it was a good deal for us! That's one thing I've mentioned to people considering this strategy: you can try it out, and if it doesn't work, you're out the hundred bucks or so for the thermostat widget - you can still use the freezer as a freezer, it's not damaged in any way.


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## byexample (Aug 28, 2009)

Wow, that's a really interesting approach to things. I've seen chest freezers converted to refrigerators via a couple different approaches. But I've never liked the idea of having to deal with the sort of problems/inconveniences described in the OP.

I had never considered the idea of using an upright freezer via after-market thermostat as a refrigerator. And I wouldn't have expected it to be that efficient.

Great post, thanks!! And thanks for providing actual measurements with your experiences. That's just great.


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## longshadowfarms (Nov 27, 2002)

Can you please explain how the external thermostat works, where you would get it, etc? We have a brand new freezer that is an absolute gem! I would LOVE to buy another like it to use as a fridge if we could get something like that. It is a chest freezer but with all the dividers in it and baskets on top, I'm pretty sure it would be easy to live with. I'll see what I can find in uprights up here too, but ANYTHING would be a huge improvement over what we now have - which is an energy hog that is bogging down our power system.

Forget it! Found one!!!!! WAHOOOOOOOOOOO!!! http://www.homebrewers.com/product/BE875/Refrigerator_Thermostat_by_Johnson_Controls.html


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## ibcnya (Feb 16, 2004)

another good article I kept. 

www.builditsolar.com/Projects/Conservation/chest_fridge.pdf


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