Electric water heaters: types and characteristics

The absence of a centralized hot water supply, temporary or permanent, makes you think about alternative ways to heat it. The water heaters will come to the rescue, which, if properly selected, successfully cope with the task. Such equipment has various sources of water heating and in some cases is equipped with a storage capacity. A wide segment of the market in the category of water heaters is occupied by flow-through electrical appliances, which will be discussed next.

Characteristics and device

A characteristic feature of electric flow-through water heaters is their compact dimensions. By practically instantaneous heating of the liquid, they provide the possibility of temperature adjustment. Drawing parallels with gas structures, the electric water heater has a significant advantage: there is no need to equip the apartment with additional engineering facilities( chimney, gas distribution).Also, its installation does not require obtaining authorization documents. If to compare with the accumulat

ive electric units( boilers) - there is a significant saving of free space.

The internal arrangement of the unit is not particularly complicated:

  • pipe for cold water inlet;
  • hot water outlet pipe;
  • switch or step-by-step adjustment of the heating temperature;
  • in selected models - rotary compressor;
  • terminals for connection to power supply;
  • holes for fixing the unit to the side surface.

Water passing through the heater, washes the heating element and heats up. Therefore, there is a regularity - the higher the head, the less heating, and vice versa. In inexpensive models, the temperature is regulated by the thermostat, the advanced models are equipped with timers and sensors that are displayed on the electronic panel. Electric flow-through water heaters have a large model range, so before you choose a favorite specimen, you should see the characteristics of each species.

Determining the required power

Avoiding frustration in operation will allow the correctly selected power of the electrical unit. To do this, it will be necessary to determine the list of actions for which it is intended and the estimated water flow. The following table will facilitate calculations:


Temperature, oC

flow, l / min










Taking a bath


The required power of the electric water heater is calculated by the formula:

P = Q x( T1-T2) x0.073, where

Q is the volume of water that the drive passes through itself( l / m);

T1 and T2 are the final and initial temperatures, respectively.

For clarity, consider an example with the following initial data:

  • The main purpose of the electric water heater is shower reception, that is, every minute supply of water should be approximately 6 liters;
  • the desired outlet temperature is 38 ° C;
  • water inlet temperature is 18 ° C( provided it is used exclusively in summer).

The required power( P) is: 6 x( 38-18) x 0.073 = 8.8 kW.

Board !Choose an electric water heater is better with a power reserve, in the case of operation of the unit for several purposes, the highest parameter is chosen based on the calculations performed.

There is a simplified method for determining the performance of an electrical appliance. In this case, its power is divided into two, the result shows how many liters of water, heated to a temperature of 35 ° C, it will give out within 1 minute. For example, at a power of 16 kW, for 1 minute you will get 8 liters of heated water, although the temperature of 35 ° C is not always acceptable. When running a running water heater for several fence points, the output of the required capacity is doubled.

It should be remembered that when installing a powerful instantaneous water heater, there may be a problem with the wiring. The apartments of the old building are not intended for the operation of electrical equipment exceeding 3,5 kW.Acquiring the unit in a modern residential building, you need to clarify the parameters of the installed wiring and fuses, in order to avoid equipment failure. In the absence of the required capacity, preliminary actions are carried out to increase the power grid.

Pressure and pressureless models

All instantaneous water heaters are divided into two main types: pressure and non-pressure. The first type includes flow units that ensure the flow of hot water over all the cranes installed in the dwelling. The process of their installation provides insertion into pipes with cold and hot water supply. Usually the work is performed by experienced specialists. Such a variant of flow-through electric water heaters is optimally chosen in the absence of a centralized hot water supply. The range includes models with top and bottom connections. The units are switched on and off automatically, triggering on the head of the liquid.

Non-pressure electric water heaters are capable of operating under low and unstable water pressure. The temperature limiter ensures that the unit is switched off in the event of a sudden drop in head pressure. This prevents consumers from getting burns and prevents damage to equipment. Non-pressure flow electric devices are limited in power up to 8 kW and are operated exclusively from one point. Therefore, for each tap will require an individual water heater. This model is better to choose for a dacha, where a small capacity will be enough. For apartments and houses with permanent residence, this option is not worthwhile to purchase.

Instrument package

You can select a quality flow-through water heater after a thorough inspection of all its components. What to look out for:

  • The heating element is protected against scale. This will significantly prolong the period of uninterrupted operation of the electrical unit.
  • Parts of the water heater in contact with the liquid must be made of copper or brass of high quality.
  • The housing is grounded to prevent people from being electrocuted.
  • Quality of the material from which the shower heads and mixers for the instantaneous water heater are made. A sufficient number of miniature apertures contributes to the comfortable adoption of the shower, even with a low head. Otherwise, the jet will not be effectively sprayed.
Note !Regular maintenance of nozzles with the use of special cleaning preparations will prolong the life of not only the components themselves, but also the entire running water heater as a whole. Otherwise, a difficult water outlet can cause the electric unit to overheat.

Control type

The running water heater is operated by a control system that is available in two versions: hydraulic or electronic. What is their difference? Budget models of flowing water heaters are equipped with hydraulic control, which allows to operate in two power modes depending on the head. When the crane is closed, the electric unit goes into the "off" mode. Models of water heaters, consuming up to 6 kW / h, provide only one-stage power. With insufficient pressure, flow-through water heaters with hydraulic control are not always switched on. The threshold of operation depends on the manufacturer's company and is different in different models.

The drawbacks of flowing electric devices with hydraulic control include the lack of ability to maintain the temperature at the same level and protection against air ingress, it is impossible to change the power smoothly. Operate them preferably in small rooms with one fence point. If the power of the instantaneous water heater does not reach the threshold of 9 kW, and it will provide several points, temperature fluctuations can not be avoided.

Electric water heaters with electronic control are located at a higher level of operation. Sensors and microprocessors installed on an electrical appliance allow you to change the heating power and head, while the control is automatic. Electronic control of flowing water heaters is presented in two versions. There are models in which only the temperature regime is adjusted. Improved electrical units have the ability to adjust the temperature and head of water.

After acquainting yourself with the calculation of the required power, the features of pressure and pressureless models, the type of control, it will be easier to choose a flowing water heater.

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