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

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.

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.