Ask what a refrigerated container does and most people say “keeps things cold”. Half true. The same machine that holds ice cream at -18 °C also heats, and that second half is barely advertised. Because the standard range runs up to +25 °C, a reefer holds a load above freezing and warms the interior whenever the outside air turns colder than your target. Through a British winter that makes it a frost-protection store — somewhere paints, resins, wine, chocolate, bottled water and other freeze-sensitive goods sit safely while an unheated warehouse or an open yard would ruin them. This guide explains how the heating works, what it protects, what it costs to run, and how to hire or buy the right unit. All UK figures below are ex VAT, with VAT charged at 20%.
A reefer heats as well as cools
A standard reefer operates anywhere from -25 °C to +25 °C, and heating is simply the warm end of that band. You set a target on the controller — say +5 °C — and the refrigeration plant works both ways: cooling when the interior is warmer than the target, heating when it is colder. In winter that means the unit sits idle in mild spells and warms the box through frosts and cold nights, holding your set point without you touching it. The refrigeration units that do this are the familiar names — Carrier, Thermo King, Daikin, Star Cool. There is no separate “heated container” to buy: any reefer in sound working order already does the job, which is worth knowing before anyone offers you a special model. How tightly a given machine holds the target depends on the unit and its condition, so match the set point to your goods rather than chasing a number on the display.
What frost protection saves
Freezing does different damage to different stock, and the value of a frost-free store is easiest to see product by product.
| Stored goods | What freezing does | Typical set point |
|---|---|---|
| Water-based paints, coatings, renders | Emulsion separates and will not re-mix | around +5 °C |
| Resins, adhesives, sealants | Crystallise or cure badly, batch lost | +5 to +15 °C |
| Wine | Expands, pushes the cork out, spoils | +10 to +14 °C |
| Chocolate and confectionery | Texture and colour go off | +12 to +18 °C |
| Bottled water and drinks | Containers split as the water expands | above 0 °C |
| Cosmetics, some medicines | Many are labelled “do not freeze” | above 0 °C |
Water freezes at 0 °C; most of the goods above want a margin over that, not a deep chill — exactly the gentle duty a reefer handles at the top of its range. Note that a container standing still is a storage question, not a transport one: ATP rules cover refrigerated transport, not a static store. And where food-safety rules such as HACCP apply they vary by country and premises, so confirm any obligation with the competent authority.
What it costs to run
Heating to hold goods just above freezing is one of the lightest jobs a reefer does. The heater only draws power when the outside air is below your set point, so through a mild winter it cycles on and off rather than running flat out. A UK reefer uses somewhere between 70 and 170 kWh a day across its full range of duties and sizes, and frost protection sits at the low end of that band — well below the 190 to 215 kWh a day a 40ft high cube burns on frozen duty. Treat any single figure as indicative: consumption moves with size, set point, insulation and how hard the winter bites. Electricity still belongs in the sums, because over a long hire it can rival the hire rate itself — our prices page sets the running cost beside the hire cost.
Who it is for
Frost protection suits anyone holding freeze-sensitive stock without a heated building to put it in: a decorator or builders’ merchant with pallets of emulsion and render over winter, a small vineyard or importer short of cellar space, a chocolatier or food producer needing a stable above-freezing hold, a cosmetics maker with “do not freeze” lines, or a site office keeping bottled water and kit from icing up. The appeal is a single machine that heats in January and chills in July — one unit, both jobs, moved on or returned when the season ends. For a fuller picture of temperatures and settings, our guides cover the range in detail.
Getting the right unit
Because any sound reefer heats, the choice is really about size, condition and how you get hold of one. A full-size unit needs a three-phase 380/400 V supply through a 32 A CEE plug and draws 5 to 12 kW while running; some small formats manage on 230 V single phase. Buying used, UK units are observed at £4,500 to £7,500 ex VAT against £18,995 to £22,500 ex VAT for a new one-trip container — see what is for sale. To hire, indicative long-term rates start around £12 a day ex VAT, though minimum terms of about 90 days are common and some suppliers offer shorter hire at a higher day rate. On a used purchase, ask for a PTI (Pre-Trip Inspection) test under three months old to confirm the unit both cools and heats. When you know the size, target temperature and how long you need it, describe your requirement once and we pass it to specialist suppliers, who contact you directly if they can meet your need.
Frequently asked questions
Can a refrigerated container heat as well as cool?
Yes. The standard range runs from -25 °C up to +25 °C, so a reefer holds a set point above freezing and switches to heating whenever the surrounding air drops below that target. The same machine that runs frozen duty in summer can hold +5 °C through a cold January, which turns it into a frost-protection store as well as a cold or frozen one.
What can you store frost-free in a heated container?
Anything spoiled by freezing: water-based paints and coatings, resins, adhesives and sealants, bottled water and drinks, wine, chocolate, and many cosmetics or medicines labelled "do not freeze". You set a target a few degrees above zero — often around +5 °C — and the unit holds it, protecting stock that an unheated warehouse or an open yard would ruin over winter.
How much electricity does frost protection use?
Less than frozen duty, as a rule. Holding a load just above freezing is a gentle, intermittent job — the heater only runs when the outside air is colder than the set point. UK reefers draw 70 to 170 kWh a day across their full range of duties, and a mild-winter frost-protection setting sits at the low end. Treat any single figure as indicative.
Do I need a special container for heated storage?
No. A standard refrigerated container already heats — there is no separate "heated" model to buy. Any reefer in sound working order does the job, so specify the size and a working refrigeration unit rather than a special feature. On a used purchase, ask for a recent PTI (Pre-Trip Inspection) test to confirm the machine both cools and heats correctly.