Repair of a gas water heater "Neva": typical malfunctions and repair technologies
Have you ever seen household appliances that have been working for many years without failure? We are sure not.Refrigerators, air conditioners, microwave ovens require periodic attention...
Moreover, you should not be upset if you need to repair your Neva gas water heater. After all, it can be done quickly, and there will be no problems with spare parts. Our article explains exactly how to identify and fix faults.
We will introduce the design features of Neva brand equipment used in heating water for hygienic and sanitary consumption. The useful information we provide will help you accurately find the cause of the breakdown. Following our advice, you can easily restore the column’s functionality.
The content of the article:
Design and operating principle of PGV "Neva"
The series of instantaneous gas water heaters (PGW) of the Neva brand includes many models and modifications. Today, the most popular are NEVA-4510M, NEVA-4511, NEVA 4513M with electric ignition.
They are manufactured at the factories of the domestic company BaltGaz Group in accordance with GOST 31856-2012 and include:
- metal case;
- gas path;
- water circuit;
- burner;
- combustion path;
- security system;
- control system;
- adjustment block.
The listed nodes consist of many elements, some of which are shown in the diagram below.
The water circuit begins with a pipe connected to the cold water pipeline and is pumped into the hot water supply pipe. This includes the water block, which plays a key role in electric ignition. It consists of a lower and upper chamber, between which there is an elastic membrane.
When the tap is turned on, a stream of cold water rushes to the heat exchanger, but along the way it passes through the lower chamber and completely fills it. Under water pressure geyser membrane bends and presses on the poppet valve of the rod located in the upper chamber.
The water block rod extends through the hole and acts on the coaxially located gas block rod. This, in turn, acts on a mechanical gas valve, the plate of which moves back and allows gas to pass through, instantly filling the burner manifold.
At the same time, when the rod moves, the microswitch plate is triggered, closing the electrical circuit.
Electrical current comes from batteries located in the battery compartment and powers the control unit, which supplies electrical voltage to the glow plug and opens the solenoid valve. Spark discharges occur between the burner nozzle and the spark plug electrode, igniting the burner.
The heat produced by burning gas is transferred to a heat exchanger pipe through which water flows. As a result, a few minutes after turning on the tap, hot water flows out of it. When the tap is turned off, the reverse processes occur and the burner goes out.
Gas is one of the cleanest types of fuel in an environmental sense, but its combustion also releases carbon dioxide, water vapor, and nitrogen. Through the gas outlet pipe and chimney of a gas boiler they are removed from the combustion chamber to the outside. Removal of combustion products is possible only if there is proper draft in the chimney.
To control the operation of the column and ensure its safe operation, the following sensors are included in the design:
- presence of flame;
- presence of traction;
- water temperature.
Thanks to these components, gas flows to the burner only when the tap is turned on and there is water in the water supply. If the burner goes out for any reason, the gas supply is immediately stopped.
The automatic shutdown of the water heater is caused by the lack of proper draft in the chimney and an increase in the water temperature at the water intake point to 90°C. If the pressure in the water circuit reaches a critical value of 1000 kPa, the emergency valve is activated and excess water is drained.
Now that you have become familiar with the structure and design of the Neva gas water heater, you can move on to the next chapter of the article, in which we will list the most common malfunctions, the causes of their occurrence and solutions.
Please take into account that the manufacturer recommends that for maintenance and repair work related to disassembling the gas-water unit, you call the service center employees with whom contract signed for the supply of gaseous fuel and equipment maintenance.
Most common faults
The following problems when using a water heater indicate malfunctions of certain components:
- the burner does not light;
- the burner does not go out;
- the column turns off spontaneously;
- insufficient water heating;
- overheating of water.
Let's look at what this looks like in practice. You turn on the faucet in the kitchen or bathroom, expecting hot water to come out. But contrary to expectations, the burner does not light. Another situation: the column starts to work normally, but soon turns off, although you did not turn off the water tap.
They wanted to wash their hands and almost got burned because boiling water was running from the tap. Or, on the contrary: you are about to take a shower, but the water is barely warm. A very unpleasant moment: you turn off the water, but the burner continues to burn.
The problems listed above can have completely different causes. Sometimes they lie on the surface, as is the case with dead batteries. But often you have to perform one complex operation after another to get to the bottom of it.
The work of home craftsmen is made difficult by the lack of experience, professional tools and thorough understanding principles of operation of a gas water heater. Therefore, when starting diagnostics and repairs, it is worth weighing all the pros and cons, guided by the principle “do no harm.”
Problems due to lack of power supply
Neva water heaters are fueled by gas, but they cannot operate without electricity. The control unit, glow plug, solenoid valve and other components of the device require a stable power supply. It is powered by two LR20 alkaline batteries, located in a separate, easily accessible compartment.
If there is no electricity, when you turn on the water tap, the spark discharge will not occur or will be weak and the column will not turn on.
Lack of power supply can be caused by discharged batteries, oxidation of the battery compartment contacts, or a break in the electrical circuit.
If the batteries are not completely discharged, they can power the display, but they will not have enough power for more energy-intensive operations. Therefore, if you see that the display is working normally and displaying temperature data, still clean the contacts of the battery compartment and replace the batteries with new similar ones or lithium CR20.
The battery compartment cover is located at the bottom of the case and is accessible without disassembling the device. That is, you can clean the contacts and replace the batteries yourself. Eliminating the causes of underheating of water.
If the column still does not turn on with new batteries, you need to check for scale in the heat exchanger pipes.
The formation of scale on the internal surfaces of the pipe prevents the normal passage of water, which can lead to the column turning off. Also, a thick deposit of magnesium and calcium salts significantly reduces thermal conductivity; the device cannot provide the heating capacity stated in the accompanying documentation, which leads to insufficient heating of the water.
Let us remind you that the operating instructions indicate that clean gas water heater and its heat exchanger is required every 12 months. When the column is used intensively and hard water is used, scale forms faster, so extraordinary cleaning may be required.
To do this, you will need to remove the casing and remove the heat exchanger. Before disassembling, close the taps on the gas and water inlet pipes. Remove the gas and water adjustment knobs by pulling them towards you. Some models have screws under the handles that can be removed with a screwdriver. Also unscrew the screws that secure the casing to the bracket from below on both sides.
The wires connecting the water temperature sensor and the control unit with the display are disconnected. Remove the casing by pulling it towards you and sliding it up. Looking ahead, we note that after repair, installation of the casing is performed in the reverse order.
So, the casing has been removed and now it is necessary to remove the heat exchanger. Unscrew the plug located under the water unit and drain the remaining water from the heat exchanger.Disconnect the column pipes from the cold and hot water pipes, remove the old gaskets. Unscrew the two screws and remove the metal plate securing the heat exchanger at the top.
Remove the heat exchanger and place it in a container with a hot solution of dishwashing detergent or regular laundry soap. After 15 minutes, use a soft brush to remove soot from the grill and other surfaces. Rinse the grill and other surfaces under a strong stream of water.
To remove scale from pipes, prepare a warm solution of citric acid at the rate of 100 grams per 1 liter of water heated to 40°C. The resulting solution is poured into the heat exchanger pipe and drained after 15 minutes. The pipe is washed with water. If necessary, repeat the procedure.
When installing the heat exchanger in place, the detachable connections are sealed with new gaskets. Do not overtighten the connections so as not to crush the gasket. Otherwise, its compressed edge may end up in the pipe in the path of water flow, which will cause unpleasant noises. Installing skewed gaskets will lead to similar consequences.
Damage to the gas-water unit
If power is provided, the heat exchanger is clean, but the water heater does not turn on, you will have to disassemble the gas-water unit to determine the condition of the membrane and rod.
Let us repeat that when repair work The gas and water supply taps must be closed. The water unit is dismantled together with the gas unit.
The gas and water supplies are turned off, the nut of the heat exchanger pipe is unscrewed, the wires connecting the solenoid valve to the control unit and the microswitch wires are disconnected.
Unscrew the screws connecting the gas-water unit and the burner manifold pipe. Now this assembly can be removed and placed on the table for further disassembly.
After unscrewing several screws, the gas block is separated from the water block and set aside. Then they work only with the water block. Unscrew the screws located around the perimeter. The block is divided into two parts, between which the membrane is located.
The membrane is removed and inspected. Most often, it is because of its stretching or breakthroughs that it is not possible to turn on the column. During reassembly, the new membrane is placed in the standard socket. The rod is installed in such a way as to ensure its translational movement without jamming.
When does a solenoid valve need to be replaced?
If the solenoid valve fails, gas does not enter the system and the column does not turn on. The valve is removed from the device, but is not disconnected from the control unit.
By simulating the supply of water to the system by moving the microswitch pusher, the ability of the valve to retract and hold the rod is determined, opening the passage of gas to the burner. If the valve does not work, replace it. To do this, disconnect the wires, remove the water-gas unit, unscrew the fastening screws, remove the old valve and install a new one in its place.
Incorrect burner operation
Displacement of the spark plug electrode or the formation of carbon deposits on it leads to the absence or weakening of the ignition spark and, as a result, to the failure of the column to turn on.Also, due to problems with the spark plug electrode, an increase in gas concentration in the combustion chamber is possible. For this reason, ignition is accompanied by a loud bang.
It is enough to clean the electrode with sandpaper and return it to its normal place so that the spark “works” and the extraneous noise disappears.
When the burner becomes clogged, its flame weakens and begins to smoke. As a result, the water does not heat up to the intended temperature. Before cleaning, remove the burner by disconnecting the wires of the ionization sensor and spark plug, unscrew the manifold pipe nut and two screws, remove the manifold, unscrew two more screws and disconnect the burner block.
Use a brush to clean the surfaces of the parts. Use a brush of a suitable size to clean the internal channels. After removing the dust, wash the parts with dishwashing detergent, rinse and, after drying, put them back in place. The flame of a clean, working burner is blue.
Sensors and electrical circuit or why the burner goes out
As was said in the chapter about the design of the water heater, the security system includes three sensors that are connected in series into a single electrical circuit.
It is enough for one of them to fail to open the electrical circuit and turn off the column.
The ionization sensor installed on the burner, as well as the glow plug, is equipped with an electrode that can become dirty or change its position, and then not “see” the flame.With such a malfunction, the water heater starts working normally, but after a few minutes the burner goes out because the solenoid valve shuts off the gas.
Cleaning the flame sensor electrode is also done with sandpaper, after which it is installed in such a way as to “see” the flame.
The gas water heater with the Neva logo also goes out due to an improperly equipped chimney or its clogging. If the draft is poor, the removal of combustion products becomes impossible. To prevent the accumulation of harmful substances in the room, the corresponding sensor is triggered and the column turns off.
When the water temperature reaches 90 degrees, the overheating sensor reacts and the column immediately stops working. The reason usually lies in incorrect adjustment of the gas and water supply, or in insufficient pressure in the water supply network.
Sometimes it is enough to turn the gas control knob towards the minimum or increase the water flow so that the dispenser stops turning off. You also need to set the “winter/summer” knob to the appropriate position in time.
Performance gas water heater sensors and the integrity of the electrical circuit is checked using a multimeter. If the sensors are working properly, the electrical resistance is close to zero.A breakdown of the overheating sensor is also indicated by an error code - the letters “EE” are displayed on the display instead of the usual water temperature indicators.
If there is no device for measuring resistance, testing is carried out by installing jumpers to close the circuit and turn on the column. If the column works normally with this connection, it means that the sensor being tested is faulty and needs to be replaced.
It must be remembered that installing jumpers is only a diagnostic method, and not a repair method. It is prohibited to use a column with jumpers instead of sensors.
Conclusions and useful video on the topic
The video demonstrates the process of replacing the batteries of the Neva water heater:
The video is devoted to typical malfunctions of gas instantaneous water heaters:
Neva geysers are unpretentious in maintenance and repairable. A minimum set of tools is required for disassembly and assembly.
The technical documentation supplied with the product provides clear troubleshooting and repair instructions. It is possible to replace individual parts and assemblies. Spare parts are available in the chain of stores of the manufacturer BaltGaz Group and at its dealers.
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