How Refrigerated (Reefer) Containers Work

A refrigerated container, known in the industry as a reefer, is a shipping container with a built in refrigeration unit that keeps its contents at a set temperature. Where a standard container simply protects goods from the weather, a reefer actively controls the climate inside, which is what makes it suitable for perishable and temperature sensitive cargo.

This guide explains how reefer containers work, the difference between operational and non operational units, and the situations where each one earns its place.

What Is a Reefer Container?

A reefer is a steel shipping container fitted with an integrated refrigeration system and insulated walls, floor and doors. The refrigeration machinery sits at one end of the unit, and the opposite end has the usual set of double doors for loading. Reefers are built to the same ISO dimensions as standard containers, so a 20ft or 40ft reefer occupies the same footprint as its dry equivalent and can be handled, stacked and transported in exactly the same way.

The key difference is the lining. The interior is finished with insulated panels and a distinctive T bar floor. Those raised channels let chilled air circulate underneath and around the cargo, keeping the temperature even from end to end rather than only near the machinery.

How the Refrigeration System Works

A reefer does not make cold so much as remove heat. The unit draws in air from inside the container, passes it across an evaporator to take out heat and moisture, and then pushes the chilled air back in through the T bar floor. The air rises up through and around the cargo, absorbs heat, and returns to the unit to be cooled again. A thermostat holds the whole space at the temperature you set.

Most reefers can hold anything from deep frozen conditions of around minus 30 degrees Celsius up to a warm plus 30 degrees Celsius, so the same unit can run as a freezer or a chiller depending on how it is set. The units we supply require a three phase electrical supply to run, which is worth confirming you can provide before you buy.

Operational and Non Operational Reefers

Not every reefer is bought for its refrigeration. There are two distinct options:

• Operational reefers: the refrigeration unit is fully working, so these are the right choice when you genuinely need temperature control, whether that is frozen, chilled or a specific holding temperature.
• Non operational reefers: the machinery has been removed, leaving a heavily insulated, sealed steel box. These make excellent insulated dry storage and are popular where a stable internal environment matters but active cooling does not.

Both share the same rugged, insulated construction, which is why a non operational unit is a straightforward way to get an insulated container without refrigeration.

Common Uses for Reefer Containers

Refrigerated containers are used wherever goods need to be kept within a controlled temperature range, including:

• Food producers and wholesalers storing chilled or frozen stock
• Breweries, distilleries and drinks producers holding product at a steady temperature
• Pharmaceutical and healthcare storage with strict temperature requirements
• Caterers and event organisers needing extra cold storage at short notice
• Farms and growers keeping produce fresh before it goes to market

Non operational units, meanwhile, suit anyone who wants a well insulated store for goods that are sensitive to temperature swings and condensation.

Buying a Reefer from Container Sales (UK) Ltd

We supply both operational and non operational refrigerated containers in 20ft and 40ft sizes across Sunderland, the North East, Teesside, Scotland and the Borders. Because we hold our own stock, we can send you photographs of the actual unit before you buy, so you can see its real condition rather than a stock image. 

If you are unsure whether an operational or non operational reefer suits your needs, get in touch and our team will talk it through with you.

Frequently Asked Questions

What is a reefer container?

A reefer is a refrigerated shipping container with a built in refrigeration unit and insulated walls, floor and doors. It keeps its contents at a set temperature, anywhere from deep frozen to chilled, which makes it suitable for perishable and temperature sensitive goods.

How do refrigerated containers work?

A reefer removes heat rather than creating cold. It draws air from inside, passes it over an evaporator to strip out heat and moisture, then circulates the chilled air up through a T bar floor and around the cargo. A thermostat holds the space at the chosen temperature.

What is the difference between an operational and non operational reefer?

An operational reefer has a working refrigeration unit for active temperature control. A non operational reefer has had the machinery removed, leaving an insulated, sealed steel container that works well as insulated dry storage but does not cool.

What power supply does a reefer container need?

The refrigerated containers we supply require a three phase electrical supply to run the refrigeration unit, so it is worth confirming you can provide this before purchase. Non operational units need no power, as they have no working machinery.

What size reefer containers are available?

Refrigerated containers are commonly available in 20ft and 40ft lengths, built to the same ISO dimensions as standard containers, so they take up the same footprint and can be handled and transported in the same way.