Chest Freezer To Fridge Conversion-The Most Energy Efficient Fridge Ever
Read this and weep all you eco enthusiasts. Want to really be “green” and cut your power consumption massively? Then you need to think a little outside of the box and do something about that power hungry tall white box in the kitchen. Let the self sufficiency website be your guide for the day.
This article will tell you how to drastically cut down on your daily electricity costs and how to convert a chest freezer in to a fridge. You won’t break the warranty, you don’t have to touch any of the inner workings of a freezer to turn it in to a fridge, and the surprising thing that we have found is that a top opening fridge is actually more convenient. First a little background:
Why Turn A Chest Freezer In To A Fridge?
We run off solar so we have always used a gas fridge. It has a small freezer compartment and a standard sized fridge compartment. It has been giving off black fumes now and then for a while and the thermocouple is also broken. It was very expensive to run but we thought there was no alternative as conventional fridges, even A plus rated ones still consume vast amounts of electricity, much more than our system will supply.
The answer is to have a fridge that uses nominal electricity and will not consume all our electric needing us to turn on a backup generator.
And we found the perfect solution. Converting a chest freezer in to a fridge.
I will get to the power consumption in a minute but first let’s see why using a chest freezer as a fridge is such a good idea.
Why Chest Freezers Are So Energy Efficient
The fact is that chest freezers are super insulated. Designed to keep items frozen for extended periods they are so much better insulated than a fridge it is not even funny.
But the real benefit is that the lid opens up rather than out as on conventional fridges and many freezers. Why is this so much of a benefit?
Cold air sinks.
So when you open your fridge or upright freezer all the cold air falls out and it then needs to consume lots of power to get the temperature back down.
With a chest freezer you open the lid up. No cold air falls out, rather it falls to the bottom. This means you lose less cold air and it will not need to consume much electric to get the temp back down.
How To Do A Chest Freezer To Fridge Conversion
Easier To Use Than A Conventional Fridge
Basically we need to override the settings on a chest freezer so that it never freezes. We need to control the temperature so that it cools only as much as a normal fridge does.
After some experimenting I have set our chest freezer to maintain a temperature between 3 and 6 degrees. This seems about right and it means that the compressor seems to hardly ever run if the fridge is not opened.
It can be hours between when it kicks in for a minute or two to maintain the temperature.
How to do it.
The Display On The Temperature controller
Well, we are in Spain which meant I finally sourced a simple temperature controller from the UK. The company were helpful with my questions and as a way of saying thank you you can buy the controller very cheaply from them (see the resources at the bottom of this article). What you then do is simple. Get an extension lead and cut the wire. You then simply wire in the little temperature controller to either side of the cut wire.
Plug the freezer in to the lead which runs to the controller and then this plugs in to the mains. No messing with the temperature sensor of the freezer itself, everything is external. No voided warranties or anything like that. There are loads of settings on this gadget and one important one is that you can set a delay ( I set it to 10 minutes) for how immediately the compressor kicks in when it reaches the higher temperature. This will prolong the life of the motor.
For those in the US you have got a real easy job. Amazon sells a simple plug in device (see resources below). You don’t need to do any wiring at all. You simply plug in your chest freezer to it and set the temperature range.
I wish I could have found one for ourselves but it was no biggie doing a little wiring anyway. Both devices have a temperature sensor that needs to be placed in the freezer. I could not get ours through the drainage hole as it has a solid end so it goes in over the top. It doesn’t seem to have affected the seal so it’s all good. I taped it to the side at about midpoint to get an average reading of the temperature in the fridge for the controller.
How Much Does My New Fridge Consume?
We bought a brand new A plus rated Zanussi chest freezer of 260 l capacity, which is the same as our old Gas fridge and more than adequate. It consumes daily between about 150 and 180 watts, give or take a few. If you want to get all fussy as I know some do and I am always getting told off here for mixing power, energy etc the new fridge consumes 0.15KWh to 0.18KWh in any given 24 hours. Did I write that correctly? There is obviously a range depending on how often the fridge is opened but that is a pretty amazing set of numbers as far as I am concerned and for average daily use it is closer to the lower figure. This is in April of 2010 in relatively warm Spain. I imagine it will increase a little as the external temperature increases.
The beauty of the external temperature controller is that you can set the desired range very easily and it displays a readout so you can see how cold or hot the fridge is.
I also used a plug in meter so that I could see how much the new chest fridge consumed and these are definitely a handy device to have anyway. You can then easily see just how much power any device consumes in any given period. And if you are on the meter you can program then with the price you pay for your power so that you can see how much it costs you. See the resources below to get this very handy gadget.
Try one on your fridge that you currently run and you will be rushing out to buy a chest freezer and external temperature controller pretty soon. But is it all roses?
It’s pros and cons time.
Pros To A Freezer To Fridge Conversion
- It easily allows those with minimal solar systems to run an electric fridge rather than expensive to buy and gas guzzling gas fridges. Our new chest freezer was actually half the cost of our Gas fridge. And that is for an A plus rated Zanussi!
- Surprisingly it is actually more convenient to use. The lift out trays and the depth for storing bottles upright (it’s vino o’clock) make it easier than trying to find things at the back of a conventional fridge shelf
- Super energy efficient, it uses what a normal 100 watt bulb would use in less than 2 hours
- Lowers the carbon footprint, especially if you run a solar system
- Very easy to do the conversion
- If you desire it is simply a matter of unplugging the chest fridge from the extension that is wired in to the temp controller and you then return it to a conventional chest freezer if you plug it directly in to the mains
What is Bad About This System
- It means there is no freezer box
- You need space to lift the lid up
- The chest freezer needs more width than an upright for the same internal space
- You have to do some wiring if you are outside of the US, but honestly it is a matter of a few wires
- It makes you totally paranoid about how much power your appliances consume (not actually a con if you ask me)
Final Thoughts And Resources
What I do find rather amazing is that there are no commercial fridges available that have a similar level of insulation. Chest freezers by design are super insulated so why not use more insulation in conventional fridges to lower their consumption. It may bulk them out a little but worldwide it would save humungous amounts of energy.
And for that matter why is there not a plethora of funky designs for fridges with doors that open up rather than out. So much power is consumed each time we open a conventional fridge as the cold air floods out. I mean, we can design all manner of funky gadgets to close kitchen cupboards slowly, automatically lower loo seats etc etc. You can’t tell me someone could not design some cool gizmo for a fridge that had a door on the top that would then also raise up the trays . But really it is not that inconvenient anyway.
If You Want To Be A Copycat
Below I will list the items you will need if you want to do something similar and get the most energy efficient fridge it is possible to have. I will put UK and US resources below so it is an easy way to allow people from those countries to see what they need. I would seriously recommend that you buy a meter that allows you to read how much energy your current appliances consume. It will probably be a real eye opener for a lot of people.
US Resources
Energy Meters to measure power consumption
Johnson Controls Manual Thermostat Control Unit
Energy Star Chest Freezers
UK Resources
The digital thermostat package I bought. If you have any questions you can email them and they are very helpful. 32 UK pounds gets you the abilty to change any freezer in to a fridge. Magic.
Efergy Esocket Plug-In Power and Energy Monitor Smart Meter
8 pounds allows you to monitor your appliances power consumption and see how great your new chest freezer is. Well worth having.
Discount Chest Freezers
Get a high rated one to start on the right path but if you already have an old chest freezer then give it a go with that.
I hope you have found this interesting. I must say I am VERY pleased with the results. It works like a charm. Runs on minimal power and means we don’t have to buy as much gas. And it really is actually easier to use a fridge with a lift up lid and lift out trays than a normal fridge, which is not what I was expecting at all.
It’s like living in the modern age but cheaper. I still find it odd hearing the hum of an electric fridge after five years with a gas one. But I am not missing lugging big red bottles in to the house every 3 or 4 weeks. And we have an extra cupboard now as well.
Related posts:
Ooh yes! I want to be a copycat! I will be passing this on to my technical department (aka long suffering partner!) Thanks for great info and a literally very cool post.
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Mr.Dirty Boots Reply:
April 10th, 2010 at 8:39 am
Hey Goo
It is definitely worth doing. I have even heard of people having good results using second hand chest freezers rather than new A rated ones. Not as efficient but still much cheaper than using a conventional fridge. Get the tech department on to it, it was a very quick job to do.
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Mr.Dirty Boots Reply:
April 10th, 2010 at 8:41 am
Thanks for that Jeff. Nice to have some more technical info, it is never my strong point. The energy meters really are well worth the price. I wish I had bought one years ago rather than to just confirm the new chest fridge really was using minimal power. I think if everyone plugged a fridge in to one they would be considering doing a conversion.
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Another thing to put on my to-do list.
As you mentioned chest freezers are certainly better insulated, but more important is the fact that they also have the condenser tube wrapped all around the outside of the cabinet to dissipate heat more efficiently. This also helps eliminate the problem of condensation around the lid seal gasket. In a conventional refrigerator/freezer an energy wasting heater strip is used around the lid or door seal to keep condensation from forming and freezing the door shut.
I’ve been using one of those Energy Watt Meters for a few months to educate some close friends about how much power they are using on common household appliances. You can verbally tell people of all the facts and numbers for the amount of energy they are using or could save, but until they see an actual number on a display does it really make them think about other options available and maybe making a few changes. It’s a great inexpensive “teaching” tool.
Thanks for another great post!
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Ostm Reply:
January 9th, 2012 at 6:15 pm
The down side to the condenser tube wrapped around the whole freezer is you can’t simply add more insulation. I’ve often wondered if one could get a cheap! chest freezer with a heat dissipation plate, so one could add 6-12″ of insulation all around and REALLY have it save energy.
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Very cool! (get it?) Only I need more FREEZER space, so how do you convert um a broken computer into a freezer?
You are very clever, and of COURSE fridges should be made this way.
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Mr.Dirty Boots Reply:
May 14th, 2010 at 7:33 am
It is working really well still. I am afraid my technical prowess is not quite up to your request though. Sorry
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Here’s an idea for a cool gizmo for a fridge that had a door on the top that would then also raise up the trays . A hinged sytem like a fishing tackle box
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Bump!
Checking to see if y’all fell off the cliff… no updates for a while.
Regarding the freezer/fridge conversion:
I first ran into a mention of it on an Australian site about a year ago, but your mention of using a beer fridge controller is perfect (he wanted to sell homemade units for $100 AU). His selling point was that his controller ran on DC power, but I believe that the first year’s energy savings would buy a big enough solar panel and inverter to run both the controller and f/f on AC.
I like Michelle’s idea for a hinged tray lifter; there would have to be a counterweight setup and gas shocks to keep the hinges from dying and the door from slamming. I think that maybe she intended to leave a link but I’m not seeing it.
My daughter uses a chest freezer for freezer-type things; she hangs her pots and pans on the wall above it.
I’m close to San Antonio, TX, trying to do something similar to your self-sufficient life but I haven’t gotten the moneymaking thing worked out yet…
Adios for now.
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Mr.Dirty Boots Reply:
June 18th, 2010 at 8:24 am
Johanna, the conversion is still working great and we are loving not needing to use the gas fridge any more. The AC use for the controller is so minimal that the savings are still absolutely enormous.
I hope you continue to be more self sufficient, but yes, finding a way to support yourself is not always easy.
Thanks for the comment. Will be back soon with new articles.
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this sounds like a neat idea….when I have a place of my own I may try to implement it….though if this place in question is an apartment I may need permission to do so from the complex managers
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I was wondering about the electricity usage of the digital thermistor when the chest freezer/fridge is not being powered. How much does the meter itself consume. I was thinking about doing this conversion myself. I just used a kill-a-watt device on my old fridge, used 4.4KwH in a 24hr period.
I was thinking of getting this pre-wired device from amazon.
http://www.amazon.com/Johnson-Controls-Digital-Thermostat-Control/dp/B00368D6JA/
Anyone experience problems with temperature variation between top and bottom being too great or having a moisture problem?
tia
Laura
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Mr.Dirty Boots Reply:
July 29th, 2010 at 10:41 am
Laura I had to use something different to that as it is for US systems but I think the usage is very minimal, my temp controller is less than half a watt so that is pretty good. Wow, the fridge you have uses a lot, you can easily get down to less than 10% of that. This unit is a little cheaper than the one you linked to but I think they do the same thing, maybe one is a newer model.
The temp difference has not been noticed by me but there is moisture in the bottom quite often. We just open the drain hole or clean it out before we put a big shop in the chest. But the main thing is it uses such little power and I actually now prefer the lift up lid design to normal fridges. Hope this helps.
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Thanks, yeah that was very helpful. I just ordered the chest freezers and will be converting 1 to a fridge. Thanks for the link. I will check out that unit as well.
Laura
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love this site! wish you had lots of pictures!!! dr. b
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Got the freezers working like a charm. I am going to borrow the power meter from the library and get some reading. As of now the freezer/fridge is on maybe fore 10 minutes every 2 hours.
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Mrs.Dirty Boots Reply:
August 22nd, 2010 at 2:52 pm
Laura,
Nice one – we are sooo happy with ours, its just so efficient.
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We are also in Southern Spain and run on solar power and have a gas fridge/freezer. We need more freezer capacity for freezing surplus vegetables. I’m finding it difficult to obtain a gas freezer here. Have you any ideas?
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Mrs.Dirty Boots Reply:
August 22nd, 2010 at 2:51 pm
Hola Alex,
Sorry we have no experience of gas freezer’s but check out you might find you can run a chest freezer on your electric set up anyway. We have various friends that do, and we have just about managed to run a borrowed one (but only in the summer as our solar set up is smaller). Just check out confort for cheap A rated small chest freezers.
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Our very old standard style refrigerator used 1600 Kw of electricity in a year (about 4.4 Kw/day), which was a total of 17.5% of our yearly household electricity consumption costing us around $260 / year.
I have run some tests on our new setup. We bought 2 chest freezers, one to act as a freezer and one which we converted.
The standard chest freezer uses on average (over a 3 day period) 0.0509192 KwH, which would be 446 Kw/Year and cost $71.37 at current rates of $0.16 / KwH.
The converted fridge is using 0.0209302 – 0.0220 KwH on average (so far only 36 hours), at it’s high end would be 193.08 Kw/Year and cost $30.89 year to run. I think I can shave this down a dollar or two as we have the temperature probe on the roof of the lid, so when the lid is open, it triggers another cooling cycle. This is partly by design to make sure everything keeps cool inside, but it most likely runs sooner than it normally would due to loss of cooling. We have a thermometer inside the fridge that almost always reads 39F. We set the temperature control device to trigger on at 40F and off at 38F. It is a very tight range that could probably be expanded a bit to allow more fluctuation. Also we might try a week of mounting the probe in the middle of the freezer to see if the temperature fluctuates much and what the energy savings might be.
So I am expecting to save 961 Kw ($153.76) a year with this new setup. We will use only 639 Kw/Year for the freezer/fridge instead of 1600 Kw with the old fridge. We spent $720 for both freezers and less than $80 for the cord + temperature controller. In energy savings alone, we will see our return on investment ($800) in 5.2 years should electricity prices remain constant, sooner if the cost increases. This doesn’t take into account the spoilage from our old fridge. With the constant temperature and minimized fluctuations, our food is keeping fresher longer, much, much longer than previously.
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Mr.Dirty Boots Reply:
September 13th, 2010 at 4:01 pm
Laura,
Thanks for such a comprehensive comment. Much better with the stats than I am ever am and it is appreciated
We just have our sensor taped to the side of the freezer and I am sure that will save you a little more.
Glad to hear from someone else that has a system like ours, I am so pleased with it, especially as we no longer have to lug heavy gas bottles about the place like we did with our old gas fridge.
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Homebrewers use freezers with controllers all the time. I do. One problem is since there is no frozen section there is nothing to remove moisture from the fridge freezer. This can lead to moisture problems. Normally in a freezer moisture is frozen out of the air or removed by a fan system but a freezer being used as a fridge doesn’t have that.
See thread http://www.tastybrew.com/forum/thread/138252. I and others use a open bucket of desiccant like “Damp-rid”.
Just food for thought.
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Allan,
Good idea, that is the one thing with fridge-freezer to fridge conversions, they do need a regular wipe-down as there is condensation. And, funnily enough after a split bag of squid incident I was starting to think a desiccant would be a good idea, and would help with smells too.
I have just popped a bowl of baking soda in there for now, but think something more powerful might be better.
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I have been doing this for 3 years. I actually replace the original thermostats with a universal thermostat for a refrigerator or chiller.
After 2.5 years my first unit failed. A hole in the aluminum evaporator coil developed. I think this was a result of too much moisture prematurely corroding the coil.
As mentioned in a few previous posts, when a freezer freezes, it removes moisture. Since the converted units don’t freeze the moisture is always there.
I waiting to see if the other units fail at 2.5 years plus.
Vance
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Recently purchased a new 150L chinese brand freezer for $185 US and then the freezer to fridge conversion termostat home brew for approx $60 US.
Conversion was pretty easy.
Power usage over the last 5 days averaged 98 Watts per day, yes you read that correct 98 Watts per DAY.
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I made incubator using digital temperature controller. I’ll try to convert chest freezer to fridge using this concept. Thank you very much. This article is very helpful.
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Hey guys I have a question, I’m thinking of doing this same thing with a remote cabin without electricity, I’m wondering what size solar panel would I need to power just the fridge freezer if I went with a small freezer (5.1 Cu. Ft.) similar to http://www.sears.com/shc/s/p_10153_12605_04619502000P?sid=IDx20070921x00003a&ci_src=14110944&ci_sku=04619502000P
I have a 90 watt panel on a 10 amp charge controller that I use on a camp trailer, would a setup similar to that be enough to power a chest fridge?
Thanks!
–Jason
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Mr.Dirty Boots Reply:
June 10th, 2011 at 7:29 am
Jason,
That sounds fine as long as you have good battery storage and that the sun actually shines for a decent amount of time
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Jason Reply:
June 10th, 2011 at 3:42 pm
okay, good deal, on my camper I use 2 120ah batteries, and I’m in Idaho, and would be using it mainly in the summer, where we get a good amount of sunlight (with sunrise at 6am and sun set at 10pm)
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