At what temperature does water turn into ice in the refrigerator: physics and practice

Have you ever wondered why in some refrigerators water in a bottle turns into ice overnight, while in others it remains liquid even after a day? The answer lies not only in the temperature settings, but also in physical processes, the design of equipment, and even the composition of the water itself. In this article we will understand at what temperature does water actually freeze in the refrigeratorwhy this indicator may differ from the classic 0°Cand how to check the operation of your freezer without special instruments.

The standard idea of water freezing as a process that occurs strictly at 0°C, only true under ideal conditions: clean water, atmospheric pressure and absence of impurities. In reality, in a refrigerator, the crystallization temperature is affected by the salinity of the water, the pressure in the chamber, the cooling rate, and even the material of the container. For example, water freezes more slowly in plastic bottles than in metal forms due to different thermal conductivities of the materials.

In addition, refrigerator manufacturers often indicate in the instructions temperature range for the freezer compartment (usually from −18°C to −24°C), but do not explain how this relates to the actual freezing of liquids. We analyzed the data for popular models (Samsung RB37J5000, LG GA-B489YEDL, ATLANT MHM 2835-100) and identified patterns that will help you more accurately control the process.

Physics of freezing: why not always 0°C?

In the school physics course we were taught that water freezes at 0°C. However, this statement is true only for distilled water in an open container at normal atmospheric pressure. In the refrigerator, the conditions are different:

• 🧊 Hypothermia: Pure water in small volumes (for example, in ice trays) can be cooled to −5°C and below, remaining liquid until a crystallization center appears (a speck of dust, an air bubble).
• 🧂 Impurities: Salts and minerals in tap water reduce the freezing point. For example, water with a high calcium content will begin to crystallize at −1...−2°C.
• 🌡️ Pressure: In hermetically sealed bottles, the pressure is higher than atmospheric, which shifts the freezing point down by 0.5–1°C.
• ❄️ Cooling speed: In freezers with a system No Frost the temperature is distributed unevenly - the walls are colder than in the center of the chamber.

Interesting fact: in industrial freezing units, temperatures of −30...−40°C are used to quickly freeze products. Under such conditions, water in the tissues of vegetables and meat crystallizes almost instantly, forming small pieces of ice that do not destroy the cellular structure. In household refrigerators, this effect is unattainable, but even the difference between −18°C and −24°C affects the texture of the ice.

Temperature in the freezer: what do the standards say?

Refrigerator manufacturers adhere to general recommendations on temperatures for freezers, but specific values depend on the class equipment:

It is important to understand that the indicated temperatures are average values in the center of the chamber. At the rear wall (where the evaporator is located) the temperature can be 2-4°C lower, and at the door shelves it can be 1-2°C higher. For example, in a refrigerator Samsung RB37J5000 with a system Twin Cooling Plus the difference between the upper and lower zones of the freezer reaches 3°C.

⚠️ Attention: If your refrigerator is equipped with a function Fast Freeze (fast freezing), the temperature temporarily drops to −28...−32°C. In this mode, the water in the ice trays freezes in 1–1.5 hours, but energy consumption increases by 20–30%.

How to check the real freezing temperature in your refrigerator?

To accurately determine at what temperature water turns into ice in yours freezer, conduct a simple experiment:

1. Pour 200 ml into 3 identical containers (plastic, glass, metal) single water (not boiled!).
2. Place them in different zones of the freezer: on the top shelf, in the middle and on the bottom.
3. Track the time and check the condition of the water every 30 minutes.
4. When the water in one of the containers begins to crystallize, measure the temperature in this zone using an infrared thermometer, a special refrigeration thermometer, a special refrigeration thermometer the results of this test: infrared thermometer or special refrigeration thermometer (price from 300 ₽).

Typical results of such a test:

• 🥤 In plastic bottles (0.5 l) water begins to freeze at −3...−4°C (due to the low thermal conductivity of plastic).
• 🍶 In glass jars crystallization starts at −2...−2.5°C.
• 🧊 In metal forms for ice ice appears already at −1.5°C.

Identical containers (3 pcs.)|Water from the same source|Thermometer for the refrigerator|Timer|Notepad for notes-->

If you do not have a thermometer, use control freezing method:

1. Pour water into the ice tray and put it in the freezer.
2. When the cubes are 50% ready (liquid + ice), note the time and compare with the passport data of your model.

⚠️ Attention: In refrigerators with a system No Frost the temperature may fluctuate by ±2°C due to auto defrost cycles. If water freezes for more than 12 hours at −18°C, this is a reason to check the door seal or temperature sensor.

The influence of the type of water on the freezing rate

The composition of water directly affects its crystallization temperature. Laboratory tests conducted in 2022 Roskachestvo showed the following patterns:

Especially influences the process water hardness. In regions with high calcium and magnesium content (for example, in Rostov-on-Don or Yekaterinburg), tap water may begin to freeze at −2...−3°C. If you use reverse osmosis filters, the crystallization temperature approaches distilled water (−0.3...−0.7°C).

Why does boiled water freeze faster?

When boiling, dissolved oxygen and some salts are removed from water, which reduces the number of centers crystallization. As a result, hypothermia occurs less intensely, and ice is formed at a higher temperature (close to 0°C).

For those who often prepare ice for cocktails or cooling drinks, the best option is to use filtered water with hardness up to 3 mEq/l. In this case, the cubes turn out transparent and freeze in 3–4 hours at −18°C.

Frequent problems: why does the water not freeze or turns into “porridge”?

If the water in your freezer behaves “wrongly” - it either remains liquid for too long or forms a loose ice mass instead of dense cubes, the reasons may be the following:

• ❄️ Thermostat malfunction: The temperature in the chamber is higher than stated. You can check by putting an outdoor thermometer in the freezer for 12 hours.
• 🚪 Worn door seal: Warm air penetrates inside, creating zones with temperatures above 0°C. Check the integrity of the rubber gasket.
• ⚡ Camera overload: If the freezer is full of food, the circulation of cold air is disrupted. Leave gaps between the bags.
• 🔄 Frequent opening of the door: Each time you open the temperature rises by 3-5°C, and recovery takes 10-15 minutes.
• ⚙️ Wrong mode: In some models (Indesit BIAA 13, Beko GNE114620X) there is an eco mode that maintains −15°C instead of −18°C.

A separate problem is the formation "snow porridge" instead of transparent ice. This occurs due to:

• 💧 High air content in the water (for example, after intensive mixing).
• 🧊 Slow freezing (temperature in the chamber is above −20°C).
• 🧂 Impurities (chlorine, iron, hydrogen sulfide), which disrupt the structure of the ice.

⚠️ Attention: If ice forms on the walls in the freezer, but the water in the containers does not freeze, this is a sign of a malfunction of the defrosting system. In this case, diagnostics of the evaporator heating element or defrost sensor is required. No Frost ice forms on the walls, but the water in the containers does not freeze, this is a sign of a malfunction of the defrosting system. In this case, diagnostics of the evaporator heating element or defrost sensor is required.

How to speed up the freezing of water: practical tips

If you need to quickly get ice, use these methods:

1. Use metal forms: Aluminum or steel trays give off heat 5–7 times faster than plastic ones.
2. Reduce the volume: Water in small containers (50–100 ml each) freezes 30–40% faster.
3. Add salt (for technical purposes): Salt solution (1 tbsp per 200 ml) begins to freeze at −5°C, but the ice turns out soft.
4. Pre-cooling: Place the water in the refrigerator (+4°C) for 1-2 hours before freezing.
5. Turn on the mode Super Freeze: In models Liebherr or Miele this will speed up the process by 2 times.

For those who like to experiment: if you need to get ice in 30–40 minutes, use dry ice (CO₂) or liquid nitrogen (available in some laboratories). In domestic conditions, it will help to speed up the process cold accumulator (place it next to the ice tray).

Myths and misconceptions about freezing water in the refrigerator

There are many myths surrounding the process of freezing water. Let's look at the most common ones:

• ❄️ "Hot water freezes faster than cold water" (Mpemba effect). This does not work in household refrigerators: hot water first cools to room temperature, and only then begins to freeze. The effect manifests itself only under specific conditions (for example, when 80% of the volume evaporates).
• 🧊 "Boiled water does not form ice". In fact, it freezes even faster than raw water due to the smaller amount of dissolved gases.
• 🌡️ "Temperature −18°C guarantees the freezing of any water". As we found out earlier, mineral or salt water can remain liquid even at −3°C.
• ⚡ "The more powerful the refrigerator, the faster the water will freeze.". The speed does not depend on the power, but on thermal conductivity of materials and the uniformity of cold distribution.

Another misconception - "ice in the freezer lasts forever". In fact, even at −18°C, ice gradually sublimates (evaporates), losing up to 5–10% of its mass per month. Therefore, if you rarely use ice, store it in airtight containers.

FAQ: Answers to frequently asked questions

Why in my refrigerator ATLANT water freezes only after day, although the temperature is −18°C?

Most likely, the problem is uneven distribution of cold. In models ATLANT with a drip defrosting system, the temperature at the door can be −12...−14°C, and at the back wall −20°C. Move the container closer to the evaporator or check if the chamber is overloaded. It is also worth checking the door seal - if it is worn out, warm air gets inside.

Is it possible to drink ice from the refrigerator if the water freezes at -3°C?

Yes, such ice is safe if the water was clean initially. A freezing point of −3°C only indicates a high mineral content, not contamination. However, if the ice is cloudy or has an unpleasant odor, this may indicate mold in the drainage system or absorption of foreign odors from the freezer. In this case, it is recommended to rinse the chamber with a soda solution (1 tablespoon per 1 liter of water).

How does the function affect water freezing No Frost?

In refrigerators with No Frost water freezes more slowly because automatic defrosting cycles. Every 6–8 hours the fan stops and the temperature briefly rises by 1–2°C. This increases the freezing time by 20–30%. To compensate for the effect, use the Fast Freeze or Super Coolmodes, if your model has them.

Why does water take longer to freeze in plastic bottles than in glass bottles?

Plastic has 20 times lower thermal conductivitythan glass (0.2 W/mK versus 1–1.15 W/mK). This means that heat from the water is transferred to the surrounding air much more slowly. In addition, plastic containers often have thicker walls, which further slows down the process. To speed up, you can use thin-walled bottles or pre-cool the water in the refrigerator.

What temperature should be in the freezer for ideal ice?

To obtain transparent and dense ice cubes optimal temperature — −20...−22°C. At −18°C, ice forms more slowly and may contain air bubbles, while at −24°C and below, the cubes are too hard and brittle. If your refrigerator does not support precise settings, use cold accumulators to locally lower the temperature in the freezing zone.