How to choose a flow electric water heater

Availability of hot water is one of the indispensable attributes of comfortable life. City dwellers are so accustomed to such conditions that temporary shutdown of hot water supply brings a lot of inconvenience. There is also a lack of hot water in the countryside, in dachas. Solve this problem can electric flow water heater. This device can supply hot water not only temporarily, but also on a permanent basis: you can build a hot water supply system for a private house.

Principle, device and features of operation

Electric flow water heater – a small-sized device that heats the water flowing through it. The heating element is a TEN (tubular electric heater) or an open spiral. Heaters with TENS are more common – they are safer and the heating element is easier to replace. In very compact models – faucet nozzles, etc.. – there is simply nowhere to put the heating element, so an open coil is used.

The device is switched on when the flow appears (the faucet is opened), it is switched off when the flow disappears. The set temperature is dialed in a few seconds, and then maintained constantly (with sufficient power of the heating element).

Externally, the usual flow electric water heater – a small plastic housing, connected to cold water and electricity. It has one outlet for hot water. Depending on its purpose, it can supply hot water to one (individual) or several (system) outlets.

The structure of the flow water heater is not complicated, there are the following elements:

• Cold water inlet. Connects to the water supply, usually with a flexible braided hose.
• Flow sensor. Tracks the appearance of water in the device (the faucet is opened) and turns on the heating element. It also turns off the heating when the flow disappears (faucet closed).
• Tank with a heating element. A small container, inside which there is a heating element, curved in the form of a spiral. This is where the water is heated.
• Hot water outlet. From the tank with water goes a tube, through which the heated water is discharged.

As you can see, the device is simple. There is also a control panel on the lid, where the conductors from the flow sensor and TEN are taken out – so that you can adjust the mode of operation and monitor the state of the device (indication of inclusion).

Types and connection to water supply and electricity

There are two main types of flow electric water heaters: pressurized and non-pressurized. Pressurized are also called system and often have the word Sistem in their name. They are connected to the water pipe, usually have a large capacity and can provide hot water to two or more water points.

Unpressurized or individual flow water heaters are connected as normal household appliances – through a flexible hose or a water pipe outlet. They supply heated water to one point, have relatively small capacity (3-7 kW) and low cost. They come in a variety of forms:

If you need to wait out a few weeks of hot water supply shutdown, you can put an individual non-pressurized electric flow water heater of any kind. If you need a constant supply of hot water, it is more rational to install a pressure unit.

Connection of a pressure water heater to the water supply system

Pressure or system electric water heaters are connected to the existing water supply system in a pipe break. They are tapped using a tee that is installed before the first branch. At the cold and hot water inlet, shut-off ball valves are placed. They disconnect the appliance if there is a centralized hot water supply. These valves are also needed so that, if necessary, the device can be removed for repair or replacement.

The quality of tap water leaves much to be desired and it is better to connect the heater after the filter. If there is no filter at the entrance to the apartment, it is desirable to install it either immediately after the branch to the apartment, or before the water heater.

In a private house, such a unit will work in the presence of a pumping station or self-assembled system with a hydroaccumulator. It is cut after all the filters, from the output comes the distribution to consumers.

Connection of unpressurized to water

Unpressurized (individual) electric flow water heater of the standard type is connected as an ordinary household appliance. There must be a branch from the water supply with a faucet and a thread on the end. With a braided flexible hose, the device is connected to the water supply.

Nozzles on the faucet for water heating are a small group. They are mainly screwed onto the thread at the end of the spout (gooseneck). To do this, the strainer, which is usually installed there, is first unscrewed.

Some time ago, there were quite a lot of them, but they were characterized by low efficiency. The nozzle itself has a solid size and you can’t attach it to a low faucet – it gets in the way. In addition, on the market there are faucets with electric water heating, which better warm water, have the ability to adjust the temperature and more convenient in handling. They are installed in place of the usual faucet on the sink or sink. The only thing that differs in the installation is the need for electrical connection.

Electrical connection

Any electric flow water heater is a powerful device and requires a separate power supply line. As an exception, you can connect to the line that goes to the electric stove – the line is suitable for the parameters. Only in this case it is necessary to make sure that the stove and the flow heater are not included in the work at the same time, otherwise the automatic machine will work on overload.

Connection of the flowing electric water heater is standard – from the panel phase from zero wind up on the two-pin RCD (be sure to break both phase and zero), then the phase is wound up and on the automatic machine and only after that is supplied to the consumer.

The connection itself can be carried out through a three-pin plug with a socket with a mandatory ground connection. You can also install a contact plate or connect the cable directly to the corresponding inputs of the heater.

Pull the power supply line with copper wire (monofilament):

• up to 7 kW cross-section 3.5 mm;
• from 7 to 12 kW – 4 mm.

The automatic unit is selected according to the maximum current consumption (available in the technical specifications). Take the nearest larger nominal value (if you take a smaller will be a lot of unnecessary tripping – every time you go to the maximum power). RCDs are taken one step higher in rating, leakage current – 10 mA.

Read more about selection of protection circuit breaker ratings here.

Type of control

Adjust the operation of the electric water heater (change the degree of heating) can be with the help of several regulators, which are located on the control panel. The control is both hydraulic and electronic.

Electric flow water heater with hydraulic control heats water by a certain number of degrees. It is always turned on with maximum power, even if it has several different heating modes. And even if one of the modes was set before turning off, it will turn on again from the maximum.

It has another feature – it heats the water by a certain number of degrees. You have to change the degree of heating manually – by switching modes after switching on. And the maximum temperature delta is usually 25°C. That is, if at the input you have water +5°C, at the output of such a device warmer than +30°C it simply can not be (at full flow). This does not mean that the unit is broken or not working properly. It means that it simply cannot make it warmer. You can slightly correct the situation by reducing the pressure, then you can achieve some increase in temperature, but you will not get full hot water in such conditions from such a unit.

Installations with electronic control usually have a large capacity and a noticeably higher price. This is because they have heating elements with multi-stage power regulation, and they are more expensive. In addition, the “stuffing” of such a device is more complex – there are several sensors, in addition, it also contains a microprocessor, which processes data and regulates the work of heaters. If the power of the unit is selected correctly, it will be able to maintain the set temperature (usually up to 40 ° C) with a deviation of one degree.

Selecting an electric flow water heater by capacity

Whatever type of electric water heater you choose, it is necessary to correctly select its power. The right thing to do, in this case, is for it to meet your expectations. It is easiest to focus on the number of taps that will require simultaneous supply of hot water:

Such capacities can withstand not all power grids. Often the total allocated power for a house or apartment is much smaller. In this case, it is worth considering the installation of less powerful individual flow water heaters or a storage water heater. An excellent option is a gas column, but it is for those who have the possibility of connecting to the gas mains.

Selection by water flow rate (capacity)

Choose an electric flow water heater can be selected by the required flow rate. There are norms of hot water consumption for different consumers. By adding up the required flow rate for your case you will get the desired figure. So, the average flow rate:

When selecting, you should have both the capacity value and the flow rate. In this case, water will be supplied to all flow points that can be operated simultaneously at the desired temperature. If not, you will have to make sure that only one tap is open at a time.

What the market has to offer

The choice of electric flow water heaters is large to say the least… It is easy to get confused. What should you pay attention to besides power and performance? On the material from which the tank and the heating element are made. The tank can be copper, stainless steel and plastic. This information is not provided by all manufacturers, but if it is not, most likely the stuffing is made of plastic. It is, of course, heat-resistant, but not as reliable as metals.

Also pay attention to the minimum and maximum pressure of cold water, at which the unit can work. There are capricious models, for the connection of which on our networks requires the installation of a reducer.

Separately, it is worth talking about taps with electric water heating. They are also called a faucet-water heater. They appeared not so long ago, but are quickly gaining popularity, since they are convenient to use, simply connected.