Off Grid Refrigerator

Off Grid Refrigerator

Postby montanamac » Sat Oct 08, 2011 2:22 pm

This is not an original idea but one that I read about some time ago. How would you like to have a method of keeping your food cold at a fraction of the electricity required for a "standard" electric refrigerator? Well ... here is method I have tried it and am very well pleased with the results. Before we get into the "how to" part we need to understand some basics.

1. heat goes up and cold goes down
2. every time you open the refrigerator door all the cold inside falls down and out!

Ever wonder how the grocery store can afford to keep all that stuff cold with no top on the cooler containing the stuff you buy? Cold goes down!

Chest type freezers keep the cold in when you open the top and I suspect they have better insulation than refrigerators. The thermostat that turns the compressor on and off in a chest freezer has settings that keep the inside temp a little above and a little below freezing.

Lets say you want to convert your chest freezer to a refrigerator to keep your stuff cold but not freezing. You could plug it in to the power outlet until the temp got down to 35 or 40 degrees and then unplug it. Then when the temp inside started to climb above 40 degrees you could plug it in again. This would work but might not be the best use of your time.

What if you had an external thermostat with a temperature probe inside the freezer / frig (FF) that will sense the inside temperature and could be set to the 35 to 40 degree range and this thermostat could turn the compressor on and off the same as you plugging and un-plugging the FF cord?

Well .... this can and does work! I have a small freezer (about 3 cubic feet) that I have been testing this theory on for a couple of weeks and it works GREAT! I have the thermostat set so the inside temp stays between 35 and 40 degrees. That's the good news. The really good news is that it works using only slightly more that one tenth the power required for my "energy star" refrigerator. In fact the actual numbers are 10.5% to 11.3% in actual measured tests using a Kill-A-Watt meter to record time and Kwh of power used.

My wife points out that the test FF is much smaller than our regular refrigerator. True, it is smaller but the principle is proven. If the FF were twice as big I doubt the power usage would double. My guess is it might increase to the 15% range if any.

There are some obstacles to overcome when switching from a "standard" upright frig to the FF. The biggest one I can think of is mentally making the change from "the way we have always done it" to something different. Once you overcome this challenge I find using the FF convenient and easy.

What about cost? A couple of days ago we made the trip to the Missoula Costco. They had a new 7 cubic foot chest freezer for sale at $175. I could envision this unit easily meeting our space needs. For the DIY person the external thermostat is available in kit form for $9 plus shipping. Other parts needed for those living "on the grid" should run around $10.

For the "off grid" bunch you will need a few more electrical parts in the range of $25 plus an inverter, battery and a way to keep the battery charged. I will be happy to provide a simple wiring diagram showing how it works.

If you are not a DIY person and would like a "plug and play" unit to convert your chest freezer to a horizontal frig ... contact Mac at 406-360-3254 and we can discuss what is needed and the cost for a "ready to go" control unit.
montanamac
 
Posts: 46
Joined: Thu Feb 04, 2010 4:47 am

Re: Off Grid Refrigerator

Postby ponun » Sat Oct 08, 2011 5:16 pm

That is the best thing since 7-up. I want one. I will be in touch. I am seriously interested.
ponun
 
Posts: 62
Joined: Sun Nov 21, 2010 2:49 am

Re: Off Grid Refrigerator

Postby jpf1030 » Sun Oct 09, 2011 5:48 am

Howdy Mac,
Great post, thanks!!! If you can post the part number and a DIY "How To" posting that may enable a lot of people to keep refrigeration going when their grid power goes down. The next time you are over, lets talk about doing some of these units, keeping an eye out for good deals on used chest freezers...jpf
jpf1030
 
Posts: 1487
Joined: Wed Feb 03, 2010 4:49 pm

Re: Off Grid Refrigerator

Postby montanamac » Wed Jul 25, 2012 1:22 pm

Just thought I would give a follow up report on our chest freezer converted to a refrigerator (FF). We have been using this converted freezer as a refrigerator for several months now. The report is 95% positive!

Here is the down side ...

Over time there will be a small amount of moisture accumulate on the sides and on the bottom of the FF. My wife simply puts a few layers of newspaper in the bottom to absorb any moisture and just replaces it now and then.

We have noticed that when placing canning jars in the FF the lids will rust over time. This could be easily overcome by using some of those plastic canning jar lids on items to be left for an extended time.

That's it!

This converted freezer keeps everything at just the right temperature. It never varies ... it is rock solid. We have one of those refrigerator thermometers that you put in the frig or freezer to check on the inside temp. The needle simply does not move ... !

If you are concerned about your power usage now or in the future or if you have given thought how you will keep your food cold when and if the grid goes down ... you might want to consider this idea that really works and works well.

I have attached a short Power Point presentation if you need more info
Attachments
Freezer to Frig.ppt
Freezer to Frig
(66 KiB) Downloaded 219 times
montanamac
 
Posts: 46
Joined: Thu Feb 04, 2010 4:47 am

Re: Off Grid Refrigerator

Postby jpf1030 » Mon Jul 30, 2012 1:57 am

Howdy Mac,
Thanks for the update. Your effort has motivated me to find a used chest freezer and get one of these "off-grid friendly" refrigerators built from one. I hope many readers will realize how valuable this info is that you have so freely given to help folks have a viable alternative energy fridge. It is fairly easy to find a cheap used chest freezer if people look around. Now is the time to do it. Get Prepared!!!...jpf
jpf1030
 
Posts: 1487
Joined: Wed Feb 03, 2010 4:49 pm


Return to Task Force #6: Alternative Energy & Transportation

Who is online

Users browsing this forum: No registered users and 1 guest

cron