The main plus of instantaneous water heaters is compactness. But at the same time, these household appliances consume a large amount of electricity. This is due to such a high power consumption, sometimes reaching 15 kW. Instantaneous water heaters belong to the class of reliable and durable devices, breakdowns rarely occur (sometimes due to a defect in production). You should know that repairing a flow-through water heater can be done by hand, it is enough to know the algorithm for finding them and purchase the necessary tools.
DIY water heater repair
Basic control systems for instantaneous water heaters
Before proceeding with the repair of an instantaneous water heater with your own hands, you should understand its structure and principle of operation. The main elements of an instantaneous water heater:
- Heating element - heating element.
- Pressure switch.
- Temperature sensor.
In addition, the circuit must have wires with different markings, as well as a button to turn on the device and adjust the water temperature (in more expensive models). Manufacturers of water heaters very often use a standard control scheme, including new elements in it.
2 water heater control schemes
Above are the diagrams of devices of different models of instantaneous water heaters. As you can see, in these water heaters, heating elements are provided, to which the electric current passes through a temperature control relay, a pressure switch and a switch. Both relays in the circuit have a protective function, and trip the network if any of the parameters are not correct. The switch is used to adjust the working power of the device.
The lower circuit is additionally equipped with an electronic board that controls the device. In both schemes, a residual current device is provided
In addition to the phase and neutral conductors, a ground connection is also provided here. The circuit is simple, you can connect it yourself using an indicator screwdriver to determine the incoming phase and zero.
Thermex water heater control circuit
The above scheme is practically no different from the previous one. A slightly different arrangement of the element, but the functionality remains the same. 2 heating elements allow you to heat the liquid more or less. The relay is responsible for their operation, the signal to which is sent by the previously installed thermostat.
An additional element in this circuit is the readout sensor, which is connected to the relay. The heating elements can be turned on in automatic mode.
How to disassemble a water heater?
To start carrying out technical work, you need to understand how to disassemble the boiler. The boiler should be serviced in several stages:
- The first thing to do is to disconnect the device from the mains. Then you can drain the water from it. If the boiler was running at full speed, it is worth letting the water cool slightly to avoid accidental burns.
- Next, remove the check valve. It can interfere with the disassembly of the water heater.
- Unscrew the screws securing the cover. We remove it.
- It is better to photograph the electrical circuit under the cover. This will help to avoid difficulties during further assembly of the device.
- Further, the payment for the operation of the water heater and thermal protection is removed. The nuts of the bracket responsible for grounding are unscrewed. They should be carefully protected from moisture. After removing the elements, a hole is formed. It should be shut up.
- The last step is to remove the thermostat from the flange sleeve.To do this, you must sharply pull it down. If the power wires interfere with this work, unscrew them in advance. Dismantle the thermostat with extreme caution, as it may be covered with limescale. Rough handling can damage the element.
In some cases, it is necessary to dismantle both the internal and external boiler control board.
Parsing the boiler
Troubleshooting Algorithm
Before you fix a malfunction, you first need to find it. Troubleshooting involves the supply of electricity to some parts of the circuit, so all work must be carried out carefully, wearing appropriate protective equipment (gloves, goggles).
Troubleshooting algorithm and elimination of the cause:
- Ensure that internal damage is not mechanical. For example, low outlet pressure is a common problem. This can happen due to a simple clogging of the watering can, which is installed on the water tap. Also, the fluid inlet and outlet pipes may become clogged. They must be cleaned with a special solution at least once every six months.
- If the mechanical part is working properly, then you should start with the input voltage. To do this, you need to purchase a multimeter - a device that allows you to make electrical measurements. Having set the appropriate value on the device (alternating voltage), one probe must be put on a phase in the terminal box, the other - to zero. A value of 220 V should appear on the screen of the multimeter. The tolerance is a value greater or less than 10 V.
Inexpensive multimeter for home appliance repair
In this way, you can check the incoming voltage on any component of the device.
- To check the temperature sensor, it is necessary to measure the voltage at the output of the device and in parallel control the temperature of the liquid. If the temperature rises above the set value, and the sensor does not break the circuit, then the element is faulty. If the voltage comes to the sensor input, but does not leave it (even when the water has not yet heated up), this also means a malfunction of the element.
- The next element in the circuit is a relay that switches the power supply from one heating element to another. It is enough to force the operating voltage to its input, and the relay will let it pass through itself. If there is no voltage at the output of the element, then this means a relay malfunction.
- The last and most important element of the electric circuit of the water heater is the heating element. The heating element is a curved tube with a metal spiral inside, on top of a ceramic body. An electric current flows in a spiral, it heats up and transfers some of the heat to the liquid. To check the heating element, it must be removed and checked for resistance. Too much resistance means a breakdown of the element, respectively - its replacement.
Heating element with a power of 1500 W
Sometimes the highest quality and most reliable way to determine a malfunction is a visual inspection of a household appliance. For example, the reason for the pressure drop may be a simple tank leak caused by a long service life and poor quality water.
What is thermal protection in an instantaneous water heater
Instantaneous water heaters are equipped with thermal protection elements - temperature control sensors. If the sensor malfunctions, the water in the device quickly reaches a high temperature, and the pressure increases accordingly. Both the water heater itself and the heating elements - heating elements - can be damaged.
Example of a temperature sensor for a boiler
The temperature control sensor works by interrupting the electrical circuit when a certain water temperature is reached. The most common overheating sensor (both electric and gas) is triggered at 60 ° C.After which the water cools down, the sensor turns on the electrical circuit, and the heating of the liquid begins anew.
In addition to the main sensor that monitors the temperature, an additional one is also installed. It carries the function of back-up shutdown of the circuit if the main sensor does not work. The reserve element will open the circuit at 90 ° C. It should be remembered that the backup sensor must be switched on manually, as it does not work in automatic mode. Usually it is turned on by replacing the main one.
How to replace a temperature sensor
The temperature sensor is usually installed as close as possible to the water outlet. Attaches to body with four bolts or Allen screws. Some models of thermal sensors have a collapsible housing, which allows you not to buy a new sensor, but to restore the old one yourself.
Temperature sensor replacement procedure:
- Drain the water.
- Remove four bolts or screws. For screws, you need to use a hexagon or a shaped screwdriver, for bolts, a suitable wrench.
- Remove the wires, having previously marked them with a marker. The wire is attached to the sensor terminals with screws. It should be remembered that before starting work, the water heater must be disconnected from the network.
- Remove the old sensor and install a new one in its place, fasten with bolts or screws. It is necessary to purchase exactly the same item, otherwise the attachment points may not match.
- Connect the wires and tighten the contact points properly.
- Fill in water and turn on the water heater. Check its functioning.
How to properly drain the water heater?
Correctly draining the water from the boiler is one of the important stages of preventive work. There are three ways to do this, the choice depends on the type of water heater:
- The device has a tee with a tap, which is located between the branch pipe and the safety valve. In this case, the flow of water is shut off, the tap opens, and excess water is removed.
- A lever can be installed on the safety valve, which regulates the access of running water. For more convenient drainage of water, a hose is connected to the lever. Water will flow through it into a container prepared in advance. The process takes a lot of time, since the water pressure is small.
- A faster way is to unscrew the safety valve. This is done counterclockwise. The pressure in this case will be strong, therefore it is recommended to connect a hose through which the water will flow into the container.
If the valve is unscrewed and water does not flow, the hot water supply system should be disconnected.
Relief valve location
The most frequent breakdowns and how to fix them
Instantaneous water heaters are simple enough if they do not have additional electronic control units. If any malfunction occurs, you can simply turn to the list for help, in which they are all indicated. The troubleshooting list also includes remedies.
Breakdown number 1: burned out heating element
The most common breakdown in which a household appliance continues to function even when the warning lamp is on, since the electric current reaches the heating element, but does not pass through it.
Burnt out heating element of the water heater
We repair the heating element in the following order:
1. Disconnect the water heater from the power supply and drain the water from it.
2. Remove the heating element. To do this, it is necessary to unscrew several bolts securing it to the body of the water heater.
3. Attach the working probes of the multimeter to the two main terminals of the heating element, having previously established the resistance measurement. The working resistance of the heating element is 32-35 Ohm. If the multimeter shows one, it means that the heating element is damaged.
The element is installed in the reverse order.Also, do not forget about the rubber gasket under the heating element. If the gasket has become unusable, then it should be replaced.
Breakdown number 2: clogging of the household appliance
A clogged water heater can result in too low outlet water pressure. An incomprehensible noise is also heard, similar to the passage of large debris through the pipes of the system.
With such a breakdown, all the working elements of the electrical circuit remain in good order, therefore, it can take a lot of time to find the malfunction. A clogged water heater does not require repair, it should only be cleaned with high quality.
Clogged water heater
The procedure for cleaning the instantaneous water heater:
1. De-energize the device and drain all water from the system.
2. It is necessary to remove 2 wires from the heating element: phase and zero. Then undock the heating device and rinse it thoroughly in hot water. Do not use hard objects to remove scale and rust, as this could damage the cell body.
3. Flush the water intake and discharge pipes under low pressure. For the best effect, it is allowed to use household chemicals with a mild effect, without active elements.
4. Install the heating element in reverse order. Switch on the device and check it for functionality.
Breakdown number 3: the power switch does not work
Multistage power switches are mainly installed on models of the latest generations of boilers. This allows you to precisely control the water temperature and save energy costs. The consequence of a breakdown of the power regulator: the device does not react in any way to the rotation of the operating mode switch knob. There may be a slightly heated liquid at the outlet, while the pressure remains normal.
Standard power switch
Most often, the power switch is a variable rheostat, which can be checked with a multimeter. It is necessary to connect the probes to the terminals of the element and smoothly rotate the adjusting knob. If the resistance changes, then the rheostat is working, if not, then it should be replaced. When replacing, it is necessary to mark the wires and connect them to the corresponding terminals of the switch. It is better to buy an original switch rather than a cheaper analogue.
Breakdown No. 4: the external tank is punctured
With a long service life, the water heater tank may leak. The quality of the heated liquid also affects the integrity of the material - very often, after several months of operation, scale forms on the surface of the heating element.
Damage to the external tank
When the body is punctured, the fluid pressure at the outlet drops sharply, the body of the device may be covered with fluid leaks. This malfunction is determined quickly by visual inspection.
Another reason for water leakage can be a worn-out rubber gasket under the heating element - the so-called flange. To replace the gasket, it is enough to drain the water, disconnect the water heater from the mains and remove the heating element. Having taken out the old gasket, it is necessary to put a new one in its place and assemble the device in the reverse order.
Repair and maintenance of water heaters
Repair of water heaters should be trusted only by professional performers. Although modern water heating systems are reliable and durable, they are not immune to breakdowns. So a high-quality repair of the boiler or other elements of the water heating system may be required at any time.
Especially if the rules for operating a boiler, radiators, water storage tanks, etc. are not followed. The master will provide all the necessary services related to the repair of water heaters - from any manufacturer and any brands.
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