When connecting modern electrical appliances to the power grid, most consumers use protection in the form of devices against overloads and leakage currents. This can be a residual current device (RCD) connected in series with the circuit breaker or a differential circuit breaker that combines the functions of an RCD and a simple circuit breaker. Depending on the type of heater (instantaneous or boiler), its power, and the number of electrical appliances, a general RCD is installed in the house on the electrical panel or a separate one (on the power cable of the water heater).
RCD and diffavtomat
Features of operation, selection and connection of RCDs
The residual current device is triggered due to problems in the network.
The protection device is necessary to de-energize the power line in the presence of short circuits and current leaks. The device operates on the principle of comparing the parameters of incoming and outgoing current. With a difference of 30 mA, the circuit is automatically opened. A person touching the equipment body cannot receive electrical injury.
Requirements for a protective device
The water heater safety device must meet the following criteria:
- Power. The indicator depends on the power rating of the home network and the number of phases.
- Voltage on the power line. Single-phase models are suitable for heaters connected to a 220 V network, three-phase - for a 380 V network.
- Degree of protection. The optimal models for an apartment are those with a shutdown for a leak of 30 mA.
- Installation location. For an apartment boiler or heater in a private house, modifications marked C16 and C25 are suitable
- Class. Class A RCDs are suitable for equipment with high energy consumption. AC class models often burn out.
The device is installed in a socket or switchboard. In the latter case, a three-core copper cable is used. Since the heater is a high-power device, you will need to ground the outlet.
What parameters should you pay attention to?
To choose the right automation that will ensure consumer safety, you should take into account the basic recommendations. The main ones are:
To summarize, as a recommendation, it should be noted that the best option is a protective device with a protection level of 30 mA. RCDs are single-phase, used for electrical networks with a voltage of 220 V. Three-phase devices are used in 380 V networks.
If an RCD is selected for a private home, then the best option is considered to be an automatic device marked C16 or C25.
Classification of residual current devices
A high-quality device ensures disconnection of energized consumers, controls the throughput of the rated current, and de-energizes the circuit when there is a difference between the input and output currents. Manufacturers produce a wide range of devices with various characteristics, based on which they are divided into several types.
Household and power traction voltage
Types of RCD
Depending on the conditions in which the RCD will operate, you can select the following types:
- AC - responds to sudden or slowly increasing changes in alternating differential sinusoidal current.
- A - triggered by a sudden increase or slow increase in the parameters of alternating sinusoidal and pulsating direct differential currents.
- B – turns off when alternating, rectified, or direct current changes.
- S and G are selective devices equipped with a switch-off time delay mode.
Models with electromechanical control are not tied to the supply voltage. The signal for them is differential current. Electronic options are powered from an electrical line or other source.
By number of poles
Depending on the characteristics of the electrical network, you can select an RCD:
- 2P, or two-pole. Suitable for single-phase lines. They are equipped with 4 pair terminals on each side for connecting to neutral and phase.
- 4P, or four-pole. Suitable for three-phase and single-phase networks. On each side of the device there are 3 terminals for phases and one for connecting the neutral.
The RCD compares currents, so the number of poles must match the number of conductors.
By rated current
The value must be equal to or greater than the total rating of the switches for the groups. For domestic use, modifications of 6000 A are suitable, but if there is a new house and a transformer station nearby, a 10 kA RCD is installed at the input.
By differential current
Optimal for the protection of humans and animals will be devices that operate at a differential current of 30 mA. Switches that operate at currents of 100 mA or more are used for fire protection purposes - they will completely de-energize the line.
The devices are mounted on the wall, on a DIN rail. There are devices that have the design of carriers, adapters, and sockets.
Typical malfunctions of the Thermex heater
The wide range of Thermex models allows you to choose a 100-liter boiler for a large family, a 10-15-liter boiler for use in a small kitchen, etc. The device is a metal heating tank, inside of which a heating element is located. The operation of the heater is controlled by a relay, as well as a thermostat. The magnesium anode helps to “soften” tap water.
It is worth noting that modern water heaters are equipped with a control unit that has a self-diagnosis function. The system detects the faulty unit and displays an error code. Having deciphered the meaning, you can understand where to look for a breakdown and how to fix it yourself.
Error table for Thermex water heaters
The video will help you deal with error E1:
Other problems with an electric water heater include:
- The appliance does not heat the water or takes too long to do so.
- Noise is heard during operation.
- Runs only for a short time.
- Doesn't work, won't turn on.
- The tank leaked.
- Unpleasant odor and color of water.
If you notice one of the signs, then proceed with inspection and repair.
Main and additional reasons for triggering
If bare wires come into contact with the body, the RCD will trip constantly.
If the boiler knocks out the machine, the reasons most often are as follows:
- Damage to the insulation of electrical models with heating elements-tubes. The protective layer is destroyed when water comes into contact with conductive components. To check the part, you will need to remove it from the tank and inspect it. Cracks indicate that the heater needs to be replaced.
- Current leaks. They occur when connecting the water heater to old wiring, a cable with exposed wires, mechanical damage to the insulation and installation errors.
- Short circuit of the exposed cable to the housing. When a bare wire comes into contact with the body, the machine will turn off permanently. The phenomenon leads to electric shock.
- The RCD does not comply with the voltage and power parameters. The knockout is periodic - the device simply cannot cope with the load.
- Malfunction of the device itself. The main reasons are wear of the trigger mechanism or a stuck test key.
Often shutdown occurs after heating the water. The malfunction occurs in boilers with deformed bodies in contact with the phase.
Why does the RCD of Termex boilers trip?
A dirty heating element can also cause the RCD to turn off.
Termex instantaneous and storage type water heaters are popular due to their ease of connection, tank capacity, good power and low cost. When an RCD is triggered during operation, it is possible that the Termex water heater is damaged or the electrical network is faulty:
- Hull breakdown. If there is grounding, the device will work immediately.
- Broken wiring in the room. Most often the neutral is damaged.
- Mechanical damage to the heating element. The heater coil comes into contact with water in the presence of permanent scale.
- Contact between housing and phase. The shutdown occurs after heating the water.
- The riser ground line is connected to the network zero. If the boiler turns on, there is a risk of injury.
- Malfunction of the RCD itself. Chinese complete devices often fail. They need to be changed.
- Exceeding the load rating. When the boiler, stove and iron are turned on at the same time, protection against network overloads is activated.
Boilers are installed only with a grounding line.
Why does an RCD trip on a Termex water heater?
2017-02-13 Evgeniy Fomenko
Let's consider the possible reasons why the RCD on the Termex water heater is triggered:
- Breakdown on the boiler body. If you have a grounding connection, the RCD will work immediately, but if you don’t have it, the power will turn off when a person touches the surface of the device. In this case, the residual current device is knocked out, and it will perform its function - there will be no electric shock.
- Zero break in the electrical wiring of the room.
- The surface of the heating element is damaged and its spiral comes into contact with water. This can happen due to the accumulation of a large amount of scale. The heating element needs to be replaced.
Boiler with two heating elements
If there are two heating elements, it is difficult to simply examine which one has a crack. To do this, you can pull out both heating elements, lower each one in turn into water and touch one wire with a probe, lowering your other hand into the water. If there is a microcrack in the shell, the light bulb will light up.
- If the residual current device turns off after the water has heated up, then perhaps due to thermal deformation, the housing begins to come into contact with the phase somewhere. You need to remove the protective cover of the boiler and carefully examine all possible contacts with the wires. The easiest way to check for voltage is with a probe.
- The RCD is triggered because the ground on your riser is connected to zero. For safety reasons, this is prohibited, but some electricians still connect this way.
- Mismatch between the power of the water heater and the characteristics of the RCD, which is why it turns off. You can view the data in the passports of both devices.
- The protection device itself is faulty or connected incorrectly. Sometimes a Termex boiler comes with a Chinese RCD of poor quality. It is advisable to buy a reliable model before installation, since the safety and health of people using hot water depends on it.
Let's figure out how the RCD works with water heaters. It connects to a cable leading to an outlet. Inside, the current flowing through the phase wire and through the neutral wire is measured. If they are equal, then everything is fine. If the values are different, this means that there is a current leak somewhere and knocks out the RCD. This protects users from electric shock.
Features of repair and replacement of RCDs
If the machine knocks out when the boiler is turned on, there is a high probability of breakdown. You can repair a faulty RCD if you have experience, tools and parts. The optimal solution for owners is to replace the device. To determine its likelihood, a monthly check is necessary. To do this, use the button to create an artificial leak.
Nuances of repair work
Before repairing, it is necessary to de-energize the network.
The difficulty of repair lies in the lack of a circuit. Therefore, when troubleshooting problems yourself, you should be guided by the following algorithm:
- Removing sealant and screws on the body.
- Removing the fasteners with a slotted screwdriver and disassembling the device.
- Making a circuit by drawing from a printed circuit board.
- Device testing. The leakage current is simulated by applying voltage from the resistor to the amplifier. A leak is indicated by the activation of the triac and the closure of the circuit.
- Troubleshooting and assembling the device.
To protect against leaks, overloads, and short circuits, the water heater must be connected through an RCD or automatic circuit breaker.
Knocking out of the boiler safety shutdown device occurs for several reasons. You can detect the breakdown yourself. Since the RCD is not equipped with a circuit and is a complex device, it is easier to replace it than to repair it.
Nuances to consider
First of all, it must be said that the RCD is a rather complex electronic device. To repair it yourself you need to be a good electronics engineer. But the best thing is to replace the RCD with a new one. In water heaters it changes along with the supply wire.
It is recommended to check the performance of the RCD monthly. The test can be performed using a special button, which is located directly on the boiler body itself. By clicking on it, the process of creating an artificial electric current leak occurs.
If the automation works, it means it is functioning normally, but if not, then you should replace the device, but before that, check if there are any problems with the water heating equipment. Based on the results, it will be possible to understand why the RCD on the water heater turns off.
How to repair Thermex yourself
Let's look at how to deal with problems on your own.
Replacing the heating element
If the body is vertical, then the heating element is located at the bottom and you don’t have to think about how to remove the cover. If there is a malfunction, the machine on the dashboard can knock out, and the body can give an electric shock. If you notice heating for too long, the element is overgrown with scale - as a result, heat transfer decreases.
Perhaps the part has worn out due to constant use or burned out due to a power surge. Read about replacing the heating element in a water heater in a separate article. In it you will find general ways to diagnose and test for functionality. We will describe the sequence of actions specifically for the Termex brand:
- Turn off the water supply and drain the liquid from the tank. To do this, loosen the nut on the hot water pipe.
- Disconnect all hoses and remove the device from the wall.
- To access the bottom, turn the body over.
- Many models are equipped with two heating devices. To avoid confusion when connecting, take a photo of the wiring.
- To gain access to the heating element, you need to disassemble the fasteners.
- Remove the screws and nuts that hold the flange of the part.
- Take it out of the tank.
If scale formation is severe, the heating element may not come out of the socket. Then carefully clean it with a thin screwdriver.
Before changing the heating element, select a replacement in accordance with the model serial number. If your appliance has two heaters, try to distribute the work evenly so that the appliance lasts longer.
Eliminating noise during operation
Magnesium and calcium salts create deposits not only on parts, but also settle at the bottom of the tank. Therefore, when switched on, noise may be heard and the circuit breaker may trip. To avoid serious problems, you need to clean the Thermex boiler at least once a year.
- Prepare the equipment: unplug it, drain the water.
- Unscrew the bolts from below and pull out the heating element.
- Clean the tank of scale deposits. If it has not dried out, it will be easier to remove it with a wooden spatula.
- For cleaning, you can use chemicals such as “Antinscale”. Or dissolve 25 ml of vinegar in 10 liters of water.
- You can clean the heater in the same solution.
- If the magnesium anode has become unusable, replace it.
Due to impurities in the water and scale, the water from the boiler could become cloudy and acquire an unpleasant odor.
Rinse the inner walls with warm water, wipe and connect the equipment.
The boiler turns off quickly or does not work at all
The main reason is the tripping of the RCD. This is possible due to a short circuit or current leakage to the housing. Besides:
- No electricity supply. Check the integrity of the power cord, plug, and the serviceability of the socket.
- Water pressure sensor malfunction. Thermex supplies water when pressure builds up in the tank. Therefore, in the event of a malfunction, the part must be replaced.
- Low pressure in the water supply. We just have to wait for its restoration.
- Electrical contacts have become loose or oxidized. Check and tighten contacts.
- Thermal sensor is faulty. Needs replacement.
Repairing housing leaks
If the housing is leaking, immediate action must be taken. Causes:
- After purchasing the equipment, no preventive inspection was carried out.
- The magnesium anode has not been changed for a long time.
- A large number of impurities in the water.
- Current leakage to the housing.
- High pressure in the pipeline (more than 2 atm), which leads to deformation of the housing. It is recommended to install a reduction gearbox.
- The sealing gasket is deformed.
To determine the location of the leak, unplug the device and use a flashlight. Carefully inspect the body. If a leak is found in the pipe connections, drain the water and reconnect the elements.
The gasket may leak. First tighten the boiler cover screws. If this does not help, install a new gasket.
Is there a leak where the heater is attached to the body?
It is necessary to completely replace it and the flange that holds the heating element. In case of depressurization of the tank itself, only a complete replacement will help, or better yet, buying new equipment.
Noticed problems at work? Take note of our publication and examine the device. If you doubt your skills, it is better to contact a specialist for repairs.
Breakdown of the EV itself (electric switch)
It is very rare, but it happens that the cause of failure of an electrical switch is a breakdown of the electrical switch itself. This idea can be suggested by checking all the reasons described above, which gave a positive result, but the machine still knocks out. Replacing the electrical switch with another new or working one will help you figure this out.
When replacing a machine, you need to pay attention to the brand of the product and the country of manufacture.
Contacts must be securely fastened
Devices from Sweden have proven themselves well, where they produce ABB brand machines together with manufacturers from Austria. French electrical switches LEGRAND and SCHNEIDER ELECTRIC are high-quality and reliable products. This also includes German electrical switches MOELLER. Although for all these products of European quality you will have to pay more than for analogues from China, you must remember that an electrical switch is a very important device, on which the condition of your property, and sometimes even your life, depends.
