Is it really necessary or a trick of the electrician to extort money from the owner?

In the previous post, you have witnessed the case of cleaning the hot and cold water heater (indirect type) for the first time after more than ten years of being forgotten. There are comments that this cleaning is unnecessary because their family’s water heater for more than 20 years has not been touched and still works well, that’s okay; others say 5-7 years is to change the bottle with a new one, without having to clean; Some even suspect that this is a trick to extort money from electricians.

So what is the real effect of hot and cold water heater maintenance and repair?

Structure of the hot and cold tank

To understand the problem, we will together “dissect” an indirect type hot and cold water heater that most households in the North are still using:

1. Bottle shell

The shell of the water heater is usually made of high-quality plastic for small bottles and powder-coated steel for large bottles.

2. Insulation layer (also known as insulation layer)

Like refrigerators, this insulation is made from polyurethane foam (PU). PU foam is injected into the space between the tank shell and the core of the bottle to retain heat, reduce heat loss to the outside, thereby saving electricity and ensuring safety for users.

3. Container gut

Unlike the direct water heater, the inner container of the indirect water heater is the part that stores water before and after heating. The normal gut will be coated with an enamel to protect the core of the vessel from the risk of corrosion causing damage, short circuit and leakage. Each brand will have a marketing style about this type of enamel such as titanium enamel, diamond enamel, …

4. Adjustment knob, temperature sensor and protection relay

The adjustment knob has the function of setting and changing the water heating temperature. When the temperature reaches the set level, the temperature sensor will transmit a signal to the relay to disconnect the power to the burner, and when the temperature drops, the relay will re-energize the burner.

In case the thermal sensor is damaged, the relay will cut off the power to the whole system to ensure the safety of people and equipment.

5. Anti-shock device (ELCB)

ELCB electric leakage wire is an indispensable part of hot and cold water heater (both direct and indirect). When detecting a leakage current flowing in the circuit, the ELCB will automatically cut off the power to avoid an unfortunate incident. To use the water heater again, it is necessary to turn on the switch (reset).

6. Heating rod (burning rod or mayso bar) and sealing rubber gasket

The burner is the part that directly heats the water in the tank. This burner is usually made of copper, steel alloy or 304 stainless steel but in general must ensure the conditions such as good heat transfer, good insulation, long life, less corrosion.

Rubber gasket is a small part that comes with the hot and cold water heater to create a tight seal, preventing water leakage to the outside during use.

7. Magnesium rod (or descaling rod)

Although the inside of the water heater has been glazed, there will still be very small spots with faulty or thin enamel, which are easy to rust or corrode when exposed to water and high temperature environments for a long time. .

Therefore, manufacturers put magnesium rods (Mg) into the hot water tank (Mg) so that it participates in a chemical reaction with some impurities in the water and helps prevent the sale of deposits on the burner as well as reducing minimizes chemical corrosion at the welds, protects the core of the vessel from being punctured.

8. Water inlet/outlet and one-way valve

The red color indicates the hot water outlet, which is conventionally placed on the left side of the tank, and the blue indicates the cold water supply line to the tank.

One-way valve (also known as safety valve) has 2 functions:

+ Only allow water to enter the tank without allowing it to flow in the opposite direction even if the supply to the system is out of water. As a result, the tank always keeps a steady amount of water to completely cover the heating rod.

+ Help to discharge water when there is a problem, remove the tank to clean or move the position.

Working principle

The function of the water heater is to heat the water (with a large capacity resistor wire) and maintain the hot water at a certain temperature. Thus, it can be said that the water heater is like a giant hydroelectric flask. When energized, current flows through the relay to the burner and heats the burner. The heat from the burner will cause the water in the tank to heat up. When the set temperature is reached, the thermostat will “tell” the relay to cut off the power. If the water in the tank cools down below the set temperature, the same temperature sensor will “request” the relay to re-energize to heat the water.

Identify

Above we have learned together about the structure as well as the operating principle of the water heater. Thereby, it can be seen that, in case the water heater still works normally after a long time, then:

1. There is still one component that “breaks” the most quickly and needs to be replaced periodically, which is the magnesium (Mg) rod.

Magnesium rod is used as a chemical agent to neutralize water, destroy chemical compounds present in water or generated during heating. It can be said that the magnesium bar is the “substitute” for the core of the tank, avoiding the corrosion of the container and it will be “weared out” during use.

Nothing is absolute and neither is the enameled surface of the hot water heater core. During the manufacturing process, it is impossible to avoid dead spots without enamel or defects with thin enamel. The more such spots, the faster the magnesium bar will melt. When the magnesium rod is completely dissolved, it is also the time when the hot water tank is not protected and needs to be replaced with another magnesium rod, otherwise the tank will be corroded and cause water leakage.

According to the recommendations of water heater manufacturers, magnesium rods need to be replaced every 1-2 years. With places with “bad” water sources, many impurities, the process of corroding magnesium rods occurs faster.

2. Heating rod (burning rod) works like a mayso in an electric kettle

For this reason, it is inevitable that calcium deposits in the water will be attached, which will reduce the water heating efficiency for a long time. It may take only 20 minutes for the kettle to heat up the water when it is first installed, but after a long time, the thick layer of calcium deposits will make it take longer to boil the water, thereby consuming electricity.

3. The process of heating water will produce limescale and impurities

Depending on the source of the water, this amount of sediment and impurities is more or less, and they will stick to the wall of the tank. If left for a long time, these deposits can damage the enamel, cause the tank to rust, cause water leakage in the water heater and can cause great danger if combined with an electrical leak.

4. The rubber seal of the water heater is subject to great pressure and high temperature when the water in the tank is heated.

Due to prolonged exposure to hot water, it expands, causing the rubber gasket to degenerate, tear, crack or harden and lose elasticity… resulting in water in the bottle leaking and seeping out the shell. the battery, thereby conducting electricity to the outside, causing a short circuit.

5. The water heater is like an electric kettle

Although the water heater is designed more modern than the water heater, but with the same operating principle, the risk of causing shock to the user of these two devices is the same because of components such as relays. , sensors, burners all have a certain lifespan.

Conclusion

At this point, you must have given yourself the answer on whether cleaning, maintenance, and maintenance of the water heater is necessary or not. In our opinion, there is a saying that “sustainability is in people”, all equipment that wants to operate stably and prolong its life needs to be serviced and maintained periodically and water heaters are no exception. Moreover, taking care of home appliances in general and water heaters in particular is also taking care of our own safety and comfort.