Two Way (Compressor) Vs Three Way Fridges – What is the difference, what is the best, and why

Overall, in most situations, we recommend a good quality compressor fridge for most camping applications, but you will need a good 12v battery and solar system to keep it going.

The best type of fridge for your caravan and camping adventures will depend on the type of camping you plan to do the most, and your off grid power availability.

Compressor fridges (two-way) tend to perform the best, especially in really hot conditions, and they are really powered efficiently. But you must have a reliable source of 12v power to run a compressor camping fridge.

If you plan to be off the grid for a significant period of time, you would need to have significant solar panel catchment and battery capacity to ensure you could last through a few days of inclement weather to power a compressor fridge with peace of mind.

The key benefit of a three-way absorption fridge is that they run very efficiently on gas, so you can be off grid for weeks at a time with no concern for weather or battery power.

The main downside of a three way fridge. However, is that overall, they do not perform as well in the hot weather.

What is the difference between a Three Way (Absorption) camping fridge and a Two Way (Compressor) camping fridge?

The two main differences between a two way fridge and a three way fridge are the fuel source they can run on, and the refrigeration process they use to cool the fridge down. 

The two way fridge can run on either 12v or 240v electricity, whereas the three way fridge can run from 12v and 240v electricity but also has the ability to run on LPG gas.

In terms of refrigeration processes, the two way fridge uses a compressor motor to cool the fridge, which is the same process used in the kitchen from your kitchen. Whereas, the three way fridge uses an absorption process to cool the fridge.

These are explained in more detail in the following paragraphs.

Understanding Two Way Compressor Fridges

How do compressor camping fridges work?

Compressor fridges are able to do what they do base on the fact that heat is absorbed when a liquid evaporates, and heat is released when a liquid condenses.

Compressor fridges are designed to capture these natural processes in a mechanical, repeatable, and controllable way. 

There are five main components required to manage this process in a continual fashion:

  • Expansion Device
  • Evaporator Coils
  • Compressor
  • Condenser Coils
  • Refrigerant

I won’t go into the minute details of each step of the refrigeration process, as that is not my area of expertise.

But what is important to understand about compressor fridges is that the power is required to run the compressor pump, which contributes to the refrigeration process by altering the state of the refrigerant.

The reason gas cannot be used in a compressor fridge is that gas cannot run a pump, electricity is required. 

Compressor Fridge Performance

Compressor camping fridges are designed to run on 12v power, and because of this, their designs have evolved to be very efficient.

In addition to being efficient with power, they also tend to be very effective even in high heat. All fridges will start to experience a decrease in cooling ability as the temperatures rise, however, the compressor fridge mechanism will perform very well against extremely hot temperatures. 

Pros

  • Very efficient with electricity
  • Don’t need ventilation
  • More effective at higher temperatures 
  • Quite resilient to off-level setup

Cons 

  • Some compressors can be noisy when operating
  • Need significant power storage to get through inclement weather periods
  • Multiple ‘moving parts’ that can fail

Understanding Three Way Absorption Fridges

How do three way fridges work?

As opposed to compressor fridges where the electricity is used to run the compressor motor, a three way absorption fridge uses a heating element to convert the refrigerant into steam.

When powered by gas, it does this with a pilot light, and in the case of 12v or 240v electricity, it does it with an electrical heating element. This steam then flows through the various components of the fridge (condenser, evaporator, etc.) to pull heat out of the fridge before being converted back into liquid. 

Given absorption fridges use electricity to power a heating element (compared to running a compressor motor), they use a lot more power to achieve the same cooling effect that could be achieved with the same amount of energy running a compressor.

But on the flip side, the gas can do this very efficiently for a very long time.

Three Way Absorption Fridge Performance

Some tropical rated absorption fridges can perform exceptionally well in high heat, but on average three way fridges have a reputation for performing less well in hot climates than their compressor counterparts.

In terms of power consumption, they are extremely efficient when run on gas. A 9kg LPG gas bottle could last up to a month for many three way fridges.

However, on electricity, they are far from efficient. If you are plugged into 240v, then there is no downside except for the electricity bill and potent performance issues in hot weather.

However, if you are using 12v power then you are very limited. Though you could run them off your battery pack or battery box, they would drain that very quickly.

The intent behind the 12v functionality is that you could run them off of 12v power while you drive, but then once stopped, revert to either gas or 240v operation. 

There are a variety of techniques people have used to try and increase the performance of their three way fridges in hot weather. The thing these methods all have in common is increasing the amount of airflow behind the fridge.

Due to the components and the way the refrigerant works, airflow is essential to a good operation which is what can be lacking in the tropics. So if you can increase airflow behind the fridge you will often see performance improve.

Pros 

  • Very efficient on gas
  • No moving parts
  • Can run on electricity if you want

Cons

  • Not efficient with electricity
  • Need ventilation
  • More sensitive to being off level

Should I get a compressor camping fridge or a three way fridge? 

The best type of fridge for you really will depend on the type of camping you want to do, and the number of batteries and solar panels you have in your setup (or are willing to get for your setup…).

If you plan to be off the grid for long periods of time, and stationary in one place for long periods of time, then you won’t be exposing your batteries to as many charging opportunities.

This means you will be dependent on weather conditions and getting enough sun to keep your batteries charged, over and above the energy you are consuming on a daily basis.

For many battery systems, more than a day or two without good sunlight and you could find yourself with insufficient battery voltage to keep your fridge running.

In situations like this, three way fridges demonstrate their value, as you could use one gas bottle to run for up to a month.
But if you have plenty of battery storage or a way to keep your battery charged (regular driving, generator, reliable sun) then a compressor may be the best option for you.

Given their performance and energy efficiency it tends to be our default recommendation, but in no way does that mean it is the best thing for you.

For you to figure out the best type of camping fridge, spend some time to map out what type of camping you think you will do, how much battery storage you plan to have, and how long this battery storage would power a fridge and all your other 12v appliances assuming you have no sun for multiple days.

That will then help you come to terms with your potential power limitations and whether you can safely rely on a compressor fridge, or whether you may be better suited to a three way fridge.

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