Among the many household lifehacks passed on from mouth to mouth, there is one particularly strange one: the advice of putting a coin in the freezer compartment of the refrigerator. Housewives there is often debate about whether this really helps preserve food during a sudden power outage. At first glance, the idea seems absurd: what can a piece of metal do in a deep freeze? However, behind this strange ritual lies a completely logical, although not always effective, attempt to create a simple defrosting indicator.
The essence of the method is to visually determine whether it was defrosted in your absence. If you're going on vacation or are simply afraid of an unstable power supply, this test may seem like a lifesaver. But is it worth relying on a copper or nickel coin, or are there more reliable ways to control your condition freezer in your absence. If you're going on vacation or are simply afraid of an unstable power supply, this test may seem like a lifesaver. But should you rely on a copper or nickel coin, or are there more reliable ways to monitor your condition? refrigerator compartment? Let's look at the physics of the process and the real reasons why people use this method.
It is important to understand that the coin itself does not cool the food and does not prolong the operation of the compressor. Its function is exclusively signaling. In conditions where temperature conditions is violated, metal can serve as a guide, but only in combination with water. Without a liquid medium, a coin in the freezer is just a foreign object, which theoretically can even cause harm if it gets into moving parts or damages the seal.
Physics of the process: how the test with a coin and water works
For the method to work, one coin is not enough. The meaning lies in the combination of a metal part and frozen water. You place a coin at the bottom of the glass, fill it with water and put it in freezer compartment til it freezes completely. After this, the glass is turned over. If the coin remains at the bottom (now the top), then the ice did not melt. If the coin slipped onto the lid, a cycle of defrosting and re-freezing occurred.
Why water and metal? When water freezes, it expands and holds the coin tightly. When thawed, the bond weakens and gravity causes the coin to fall. This is the simplest mechanical indicatorthat does not require batteries or electronics. However, it is worth considering that if the defrosting was short-lived and the ice only slightly melted at the edges, the coin may not move, creating a false sense of security.
⚠️ Attention: Do not just put the coin on a shelf or food. At best, it will get lost among the vegetables, at worst, it will fall into the drainage hole or damage the plastic tray if handled carelessly.
The effectiveness of this test depends on the temperature in the room and the duration of the light outage. If the apartment is hot, the ice in the glass will melt quickly and you will receive a signal. But if the freezer is full and the door has not been opened, the food may last longer than the ice in the small glass will melt. Therefore, you should not rely solely on this method in case of long-term absence.
Coin as protection against power surges: myth or reality
There is another common misconception that a coin in the refrigerator can somehow protect equipment from power surges. People believe that the metal “takes the blow” or stabilizes electric field inside the chamber. From the point of view of physics and electrical engineering, this is absolutely false. A coin lying on a shelf or in the freezer does not in any way affect the operation of of the compressor or the electronic control board.
To protect the refrigerator from voltage surges, there are special devices: stabilizers, voltage monitoring relays or surge protectors. They are the ones who should stand between the outlet and the appliance. The coin is a conductor, and if it accidentally comes into contact with bare wires (for example, if the insulation of a defrost heating element is damaged), it can cause a short circuit rather than prevent it.
Some users confuse this myth with real grounding recommendations. Proper grounding of the refrigerator body is indeed important for safety, but it is implemented through electrical wiring apartments, and not through objects inside the chambers. The attempt to use a coin as a “lightning rod” inside a plastic container has no technical basis.
Where did the myth about protection with a coin come from?
Most likely, this is distorted information that in old Soviet refrigerators they sometimes used metal objects to improve heat dissipation or fixation, but this had nothing to do with electrical protection.
Thus, if your goal is to protect expensive equipment from burning out during network surges, the coin is useless. Moreover, storing metal objects in the evaporator area or near heating elements can be dangerous. It’s better to invest in a high-quality one surge filter with an overload protection function.
How to properly conduct a defrosting test
If you still decide to use the coin method to monitor the condition of food during the holidays, it is important to perform the procedure correctly. Mistakes in preparation can lead to false results, causing you to believe that food is frozen when it has already started to spoil. First, prepare a clean container and water.
Here are step-by-step instructions on how to make defrost indicator with your own hands:
- 💧 Take a transparent plastic glass or a small container that you don’t mind leaving in freezer.
- 🪙 Place any coin on the bottom (preferably a large one so that it is clearly visible).
- 🚰 Pour water so that it completely covers the coin and place it in the freezer until completely frozen.
- ❄️ After freezing, turn the glass upside down bottom The coin should remain at the “bottom” (which is now on top).
Now this glass can be left in freezer compartment. When you return, just look at the position of the coin. If it slides down (toward the lid), then the ice has melted. However, remember: if the layer of ice was thick, the coin could only move from the surface while the food inside was still cold. Therefore, this method is good for recording the fact of defrosting, but bad for assessing the depth of the problem.
☑️ Check before leaving
It is also worth considering the material of the container. Glass can burst if there is a sudden change in temperature, so it is better to use plastic. Make sure the glass is stable and will not fall when you open refrigerator door on your return.
Comparison of methods: coin vs. smart technology
In the age of the Internet of Things, relying on a glass of water seems archaic. Modern refrigerators offer much more advanced solutions. Let's compare the effectiveness of the "old-fashioned" method with modern control technologies.
| Parameter | Coin in a glass | Smart refrigerator (Wi-Fi) | Separate thermometer-logger |
|---|---|---|---|
| Accuracy | Low (fact of melting) | High (degree by degree) | Very high |
| Notification speed | Only when return | Instantly to the phone | When reading data |
| Cost | 0 rubles | High (price of equipment) | Low (500-1000 rubles) |
| Reliability | Depends on the volume of ice | Depends on electricity and network | High (autonomous) |
As can be seen from the table, smart technologies they win in all respects except cost. A notification will be sent to your smartphone the moment the lights just go out or the temperature starts to rise. This will allow you to react even if you are far away. The coin will tell you about the problem after the fact.
However, if you have a regular model without Smart functions, simple mechanical or electronic thermometers for refrigerators can be an alternative. They are inexpensive and show the current temperature. But they do not record history: if the light is distant and the temperature drops again, the thermometer will show normal, and you will not know about the jump.
The real risks of storing coins in the refrigerator
Although the idea of a defrost test seems harmless, storing metal objects in the refrigerator carries certain risks. First of all, it's hygiene. Coins are one of the dirtiest items in everyday life. A huge number of bacteria accumulate on their surface, which, when defrosted, can get on food or inside air circulation systems.
Secondly, there is a risk of mechanical damage. If a coin falls out of the glass and rolls behind the drawer, it may fall into the operating area of the fan No Frost or defrost heater. The rotating blades can crumble the metal and scatter pieces throughout the chamber, requiring extensive cleaning and potentially repair.
⚠️ Attention: Metal objects should not be placed directly on glass shelves or near heating elements. With thermal expansion, metal can crack glass or damage plastic.
It is also worth remembering about oxidation. In high humidity conditions, some alloys may oxidize, leaving a residue on the walls of the chamber or cookware. Although modern coins are made from stable alloys, the risk of a chemical reaction with product vapors or detergents cannot be completely excluded.
Alternative methods of temperature control
If you want to be sure of the safety of products, it is better to use specialized means. The market offers many solutions that are more reliable than coins. For example, there are stickers or devices that change color irreversibly if the temperature rises above a certain threshold. Thermal indicators Another option is the use of temperature. These are small devices that record a graph of temperature changes over a certain period. You can leave such a gadget in the refrigerator while on vacation, and read the data via USB or Bluetooth when you return. This will give an accurate picture of what happened with temperature indicators - stickers or devices that change color irreversibly if the temperature rises above a certain threshold.
Another option is to use digital loggers temperature. These are small devices that record a graph of temperature changes over a certain period. You can leave such a gadget in the refrigerator while on vacation, and read the data via USB or Bluetooth when you return. This will give an accurate picture of what happened to microclimate cameras.
Don't forget about the basic rules: before leaving, load the freezer as much as possible. Products that are already frozen act as cold accumulators. An empty refrigerator defrosts faster than a full one. If there is little food, fill the free space with bottles of water - this will prolong the cold much more effectively than one coin.
Frequently asked questions (FAQ)
Is it true that a coin helps the refrigerator work more economically?
No, it's a myth. The coin does not affect compressor operation, heat transfer or electricity consumption. Savings can only be achieved by correctly loading the chambers and the serviceability of the seals.
Which coin is best to use for the test?
Coins of large diameter (for example, 5 or 10 rubles) are best suited, as they are easier to notice. The material is not important, the main thing is that the coin does not rust instantly, although in a frozen state this is not critical.
What to do if the coin has moved, but there is still ice?
This means that the top layer of ice has melted. The food in the depths may still be frozen, but the risk of bacterial growth already exists. It is recommended to check the condition of perishable foods (meat, fish) by smell and appearance before consumption.
Can this method be used in a No Frost freezer?
Yes, you can. In No Frost systems, cyclic defrosting also occurs, but it is short-term. A glass of water will freeze, but if the power goes out for a long time, the method will work. The main thing is to securely fasten the glass so that it is not blown away by the fan.
Is there a more reliable way than a coin?
Yes, the most reliable way is to install a temperature alarm with a GSM module or connect the refrigerator to the Smart Home system. They will send an SMS or push notification immediately when the temperature rises.