Why does the kettle turn off to boil water

Today, on the shelves of specialized stores for the sale of household appliances for the home you can find a variety of the latest models of electric kettles from different manufacturers. These devices are quite reliable and unpretentious in everyday life, but sometimes there can be a situation when an electric kettle, before working properly, suddenly turns off, although the water is not heated to boil. No need to panic, call the master or throw the device into a landfill, let's see and find out all the causes of product failure.

Scheme and principle of operation

To understand why this happens, you need to know the principle of operation of the kettle and its electrical circuit. The model range of these household appliances is very diverse, but the principle of operation and the assembly scheme are almost identical for everyone, with rare exceptions: for example, the built-in timer.

The electric kettle works quite simply: through a strong cord with a plug at the end, the voltage from the outlet is transmitted to the XP1 contacts located in massive stand - it is the device that is installed during boiling water. In the lower part of its body there is a special connector that interacts with the contacts of the stand.

Thermal switch SA1 provides manual on and automatic shutdown of the appliance after water begins to boil. The thermal protection switch is always active and does not take part in the daily work of the product - it only works when the kettle turns on without water. Then the current goes to tubular heating element (TEN), and the illuminated light on the indicator indicates that the product is in operation.

When water boils, steam is collected in the free space between the water level and the lid of the product, then water vapor through a special channel comes to bimetallic platemade of two different metals, which bends from the heating and opens the contacts - the thermal switch is turned off.

Protection system

The heating elements on the electric kettle are installed during assembly at the factory and depend on its volume: the power of the heating element varies between 0.5-2.5 kW. When heated, they emit a large amount of heat, so in order to avoid a fire, the designers have provided effective protection against overheating.

Round bimetallic plates are used as temperature sensorsIn the center a special selection is made. They should fit snugly to the bottom of the kettle, for better heat transfer, their surface is smeared with a paste with excellent heat-conducting properties.

It is not recommended to remove this grease during any repair.

Temperature sensor

The plate is assembled from two metals with different thermal expansion coefficients, firmly glued together. With strong heating, it bends due to the different expansion of metals.

To turn off the device, the bimetallic plate is connected to the contacts by ceramic stock as follows: one end of it rests on the disk, and the second - props the plate of the contact group.The mechanism of action is very simple: the plate is bent, the rod starts to move and the contacts are turned off.

Ceramic rod and bimetallic plate

This type of protection has only one negative nuance - after cooling, the membrane returns to its original state, and the contacts can close - the heating element will start heating. To prevent the electric kettle from switching on independently, two such disks are installed: one works in the overheat protection system, the second is connected directly to the switch and completely disconnects the device from the mains voltage.

Causes of failure

So, why does the kettle turn off without boiling water?

1. The most common cause of such a malfunction is bimetallic plate defect. The metal from which it is made undergoes multiple expansion-contraction during the operation of the device. It is not surprising that over time the plate is deformed and loses its properties, therefore it turns off the electric kettle at the wrong moment. Of course, this applies only to those devices that have worked for more than one year. Although low-quality Chinese products can “please” the owner with such a defect in just a few months after purchase.You can fix the plate: bend it to the correct position. However, this is a temporary measure, and soon the kettle will have to be changed, because repair (replacement of the plate) in this case is unprofitable.
2. Another common reason why an electric kettle can turn off before boiling water is scum on the bottom and walls of the product. Especially this often happens with models with open heating elements - it overheats, and the device is protected from overheating. To remove the formations, it is enough to boil the minimum amount of water with the addition of one packet of citric acid - this procedure can be repeated several times. To speed up the process of getting rid of plaque, you can add a couple of tablespoons of vinegar - this will speed up the cleaning.
   
3. If it's not a scum, then maybe thermostat broken. You can contact a specialist to replace it, but it is easier to buy a new product - the price of repair is approximately equal to the cost of a new kettle.
4. The reason for the shutdown before boiling water can be broken or poorly manufactured switch - if the device turned off before the time, and after 15 minutes (during this time the bimetallic platinum cools and returns to its original position)switched on independently, this is a signal to the user that the switch does not work correctly.
5. Frequent product leaks, even in the form of a few drops, lead to the fact that the kettle turned off before the water boiled. It is necessary to check the device case - according to statistics, most often microcracks due to temperature differences occur with devices whose case is made of glass or plastic.
6. Loose mounting TEN to the body of the product is often the reason for premature shutdown of the device. If you use the product with an open type heating element, then it will be easy to check it, even without disassembling the kettle. If the TEN is of a closed type, then you should contact the service center for the help of a specialist - it is better not to go inside the product yourself.
7. With prolonged use rubber gasketwhich serves as an insulator between the case and the compartment on the bottom, where the heating element is located, may wear out, but this fact cannot be verified without complete dismantling of the device. This information is useful to home craftsmen, who independently decided to find the reasons for the failure of the device.

In order for the kettle not to turn off until the water boils, you must carefully select the device at the time of purchase, preferring proven manufacturers.