How to choose a instantaneous water heater: a review of types of instantaneous water heaters and tips for buyers

Agree, it’s great when hot water always flows from the tap, regardless of its supply from the city utility company.The problem of interruptions will be solved by installing an instantaneous water heater. But the variety of offers on the market is amazing, and you want to buy the best model and don’t know which one to choose?

We will tell you how to choose an instantaneous water heater that has the necessary technical characteristics. We'll tell you how to choose it taking into account operating conditions. Let us indicate what capabilities the equipment should be equipped with to meet the individual needs of users.

The article discusses the main criteria for choosing the optimal model and provides a rating of the most popular water heaters. Attached are photographic materials and useful video recommendations that will help you decide on the best flow machine.

Design and operating principle

The design of an instantaneous water heater is not complicated: a small water tank is enclosed in a metal or plastic case, equipped with heating elements or a spiral.

Budget appliances most often have 1-2 heating elements, which have a weak point: the heating elements quickly become overgrown with scale. The good news is that they are easy to replace.

Less scale is formed in devices with a spiral enclosed inside a copper tube.The disadvantage of such a device is a negative reaction to bubbles and air pockets. If the equipment fails, replacement will be expensive.

The heating principle is simple: cold water enters the tank, comes into contact with hot elements, heats up and comes out with the required temperature parameters (on average from + 40 °C to + 60 °C).

To install compact equipment, you need a mounting kit, water supply and electrical cable.

Schematic representation of a household flow-through electrical device with an electronic control unit, in which water is heated using a copper heating element

Powerful equipment designed for several water points requires good flow and high pressure. Non-pressure devices operating at low pressure can sufficiently serve only one tap.

For this reason, they are initially equipped with “custom” devices - a gooseneck or a flexible hose with a diffuser.

The heating process occurs instantly, so there is no need to wait for a certain amount of hot water to accumulate. Electricity is only consumed when the device is operating.

Unlike its storage counterpart, a instantaneous water heater takes up minimal space. Usually it is fixed on the wall near the water point (sink or shower) in a vertical position

If we compare flow models with storage models, we can highlight the following advantages:

• space saving, compact size (important for rooms with limited free space);
• possibility of installation both near the tap (minimizing heat loss) and in a separate room (applies to powerful appliances);
• the amount of water consumed is not limited;
• interval power consumption (only during the active period);
• beautiful, laconic design;
• low cost.

The disadvantages include regular costs for paying for electricity: the more often the water heater is turned on (respectively, the larger the family), the higher the electricity bill.

Installation diagram of one device on two mixers. When choosing, you should focus on the power rating of the device. If it is not enough, the device can serve only one tap at a time (maximum – tap and shower)

Another disadvantage concerns the installation conditions. For water heaters with a power of 7-8 kW and above, a reliable three-phase electrical network, high-quality copper wiring and appropriate protection are required.

The presence of built-in furniture in the room makes it possible to hide the wall duct in one of the wall cabinets. A prerequisite is easy access to the housing, control unit and significant components for maintenance

Why is an electric model better than a gas model?

In city apartments there is no need to choose between two types of devices, since they usually use electric, safer models.

The exception is apartments in which geysers were installed during the process of equipping the premises upon delivery of the house. This applies to “Khrushchev”, “Stalin” and some types of panel houses built in the 60-70s of the last century.

Diagram of the gas water heater. A necessary condition for its operation is water pressure of at least 0.25-0.33 atm (approximately 1.5-2 l/min), otherwise the heating elements will not turn on

In country houses, water is often heated using a powerful floor-standing boiler, but some people prefer to use a gas water heater out of habit.

Its use is appropriate for stove heating or in warm climates that do not require the installation of heating equipment.

Considered safer electric flowers, although their operation is more expensive than using geysers. In addition, when heating with gas, exhaust hood and reliable ventilation are required, otherwise there will be a risk of carbon monoxide poisoning. Savings are considered a plus, since gas prices are lower than electricity.

In older houses, it is not possible to use a powerful electric appliance (above 3.5 kW), so you will have to make do with either a weak water heater or geyser. Thus, if there is a choice, consider the state of electrical networks and ventilation, water pressure, and the cost of fuel (gas or electricity).

With landmarks choosing a water heater We invite you to read the article dedicated to these issues.

Differences between free-flow and pressure devices

The difference between a non-pressure device is that the pressure inside it does not exceed atmospheric pressure, while a pressure water heater always experiences the pressure of the main water.

The non-pressure device protects the tap installed at the inlet from tap water pressure. Models of this type have low power (2-6 kW), do not provide sufficient water heating and are most often used in dachas or temporary residences.

Non-pressure models are designed to serve one point, therefore they are equipped with a watering can, tap or a tap + shower set. The load is small and replacement of the wiring with a more reliable one is not required

The pressure device does not have attachments and is a mini boiler with an inlet and an outlet. One device can be simultaneously connected to several analysis points at once.

Their power is enough to provide hot water to a kitchen sink, a shower, and a couple more taps. There are 2 categories of pressure devices - single-phase (3-12 kW) and three-phase (3-30 kW).

The location of the pressure water heater is under the sink, on the wall or in a cabinet. It is able to maintain a set water temperature and has an automatic on/off function

The disadvantages of a pressure device are a higher price and increased electricity consumption, however, during a period of hot water outage in a city apartment in which a large family lives, one cannot do without it.

Features of choosing flow-through models

Due to the diverse requirements of users and the high demand for water heating devices, the market is filled with models with different technical characteristics.

To decide which instantaneous water heater from those provided is better and more suitable specifically for you, pay attention to criteria such as power, performance and the presence of additional functions.

Criterion #1 - power and performance parameters

Power is a decisive criterion that affects the amount of hot water heated in a certain period of time. If you need to quickly take a shower or cook dinner, a low-power device that can heat 3-5 liters of water within a minute is enough.

Heating is carried out quickly, in just 20-25 seconds. For increased needs, we recommend taking a closer look at more powerful models.

Using the table, you can determine your family's hot water needs. The number of family members and the number of water points are taken into account

To calculate power you can use the generally accepted formula:

P = Q x (t₁ -t₂) x 0.073,

Where:

• P(W) — power;
• Q (l/min) - hot water flow;
• t₁ (°C) - required hot water temperature;
• t₂ (°C) - water temperature in the water supply;
• 0,073 - correction factor.

In order not to make complex calculations, look at the manufacturer’s recommendations - the purpose of the water heater is usually indicated there.

For example, devices with a power of up to 8 kW are recommended to be installed in dachas where there is no need for constant heating. An average temperature of 40-50 °C is enough to quickly wash or wash several dishes.

If you want to purchase a serious device for constant maintenance of your home or apartment, consider models with a power of at least 20 kW. When choosing, try to take into account the installation locations of water points.

If the shower and sink are located next to each other through the wall, it is possible to install one product far from each other - you will have to buy two low-power devices or one more powerful pressure water heater.

The model for the dacha is an instantaneous electric water heater Kospel EPJ 3.5 Optimus. Power – 5.5 kW; voltage – 220 V; productivity – 2.7 l/min (at a temperature of 30 °C); equipped with thermal protection and a tap with water heater Kospel EPJ 3.5 Optimus cutter

A few words about the weakest models, whose power does not exceed 3-4 kW. They are designed mainly for use during warm periods, when the average water temperature in the mains is 18-20 °C.

If you want to take a hot shower in winter (just during the period when accidents often occur), choose models with a power of 6 kW and above.

The power and performance of the device are indicated in the technical data sheet of the products, as well as on the price tags in the explanatory descriptions. On online store websites, exact data can be found in the “Technical Specifications” section.

Criterion #2 - control types and modes

Despite the simplicity of the design, flow models are divided into two categories based on the type of control:

• hydraulic;
• electronic.

Hydraulic (or mechanical) control typical for all budget class models.It is usually presented in the form of a step switch. Some models do not have the ability to adjust temperature or water pressure at all.

Budget model for temporary use Electrolux Smartfix 2.0 S with a power of 3.5 kW with hydraulic control and three operating modes. According to reviews, it is suitable for infrequent use in a city apartment. It was not possible to heat cold water from a well at the dacha with a device of this type

The control principle is as follows. Levers or buttons located in accessible places on the body operate the stem. Depending on the position of the rod, the water pressure may change, and as a result, the temperature.

The main disadvantage of models of this type is the lack of precise adjustment and maintaining a constant mode. If the water pressure in the main is weak, the device may not turn on at all.

By using electronic mechanism management You can set the required water pressure or maximum heating.

Built-in microprocessors and sensors respond to changes in pressure and temperature, changing parameters according to the selected mode. Using various modes, you can select the optimal parameters to save energy.

Three-phase instantaneous water heater Stiebel Eltron DHE pressure type with electronic control of power and water flow. Touch control, smooth temperature control from +20 °C to +60 °C, indication on LCD display

The disadvantage of models with electronic control is their high price, the main advantage is the ability to select the required mode (maximum, minimum, economical).

Mechanical control is permissible when the device is installed to serve one shower or one sink - you can use the switch at any time and change the parameters.Electronic control is good in cases where one pressure water heater serves several water points.

Criterion #3 - availability of additional options

The design of budget models is simple, since they do not have additional functions, but equipping more expensive models with electronics makes the life of users much more comfortable.

When choosing, pay attention to such characteristics as:

• several power modes;
• indication of switching on and heating;
• overheat protection;
• temperature limitation (maximum and minimum);
• protection against hard water;
• scale protection;
• check valve;
• programming function.

The listed characteristics are typical for middle-class models costing 15-20 thousand rubles. More interesting, narrowly targeted options can be found on expensive devices. For example, many AEG brand products are suitable for connection to solar panels - input heating up to +60 °C.

In-line model AEG DDLE with LCD display and power adjustment from 18 kW to 24 kW. Additional functions: display color change when the temperature reaches 42.5 °C from blue to red, ECO option, contrast shower

The German company Stiebel Eltron produces models in which, in addition to the now familiar child lock (a rare protection specifically for water heaters), there is a set of useful programs, including 4 contrast shower modes.

Criteria for choosing a geyser in accordance with water consumption and personal requirements are given here.

Features of wall mounting

Instantaneous water heaters are installed in a place convenient for control, most often on the wall near the sink or shower.For fastening to concrete panels or brick walls, dowels are used; for drywall (not recommended) - special moth-type devices. The product should be positioned according to the instructions; it should not be rotated.

If you plan to install the water heating device near the water point, that is, in the bathroom or in a combined toilet, make sure that the degree of protection is not lower than IPX4

Connection to the electrical network must be made via RCD, especially if the manufacturer does not provide a protective automatic shutdown function.

A three-core copper cable is pulled from a common grounding panel, then either a differential switch or a circuit breaker is installed.

Installation diagram for instantaneous water heater: 1 – pipe with cold water; 2 – tap (mixer); 3 – shut-off valves; 4 – check valve + filter set; 5 – RCD; 6 – electrical panel

It is better to equip the supply pipes for a pressure water heater with ball valves - for ease of installation/dismantling. Remember that a free-flow device has only one pipe - for connecting cold water.

More details with rules installation of ducts You can find it in the article presented to your attention.

Rating of famous manufacturers

The main criteria by which products from well-known manufacturers are evaluated are quality, warranty period, standard functions, availability of additional options, variety of models.

The price of products can be ignored, since each manufacturer has lines of low, medium and high price categories.

Place #1 - Stiebel Eltron

The German company Stiebel Eltron produces impeccable equipment with a 3-year warranty. Known for producing powerful pressure water heaters with a set of additional functions.Easy installation and ease of operation, many convenient modes, temperature and pressure adjustment - outstanding qualities plus German reliability.

Model Stiebel Eltron DHB-E 13 SLi for wall mounting. Power – 13 kW, degree of protection IP 25, electronic control, emergency shutdown function

Place #2 - AEG

German manufacturer AEG, which has proven itself to be of excellent quality products. The devices last a long time and rarely end up in service centers for repairs.

In Russia, a line of single-phase devices from the “mini” series, compact and economical, has become popular.

Instantaneous water heater AEG MTD 570 with a laconic design. Power 5.7 kW; productivity – 2.9 l/min; temperature is adjusted using hydraulic control

Place #3 – Electrolux

The Swedish company Electrolux, known for its variety of models in the mid-price segment.

Compact but quite powerful devices are cheaper than their German counterparts due to the use of less reliable materials in the design. Most of the products are made in China.

Flow-through model Electrolux NPX6 Aquatronic with a power of 5.7 kW with electronic-mechanical control. Equipped with an automatic on/off function, maximum heating temperature - +50 °C

Location #4 – Atmor

Israeli brand Atmor, which produces budget devices for home and garden. Compact devices with mechanical control have several operating modes, good well-functioning automation and overheat protection.

Atmor Basic shower model. It has three operating modes - with a heating power of 2/3/5 kW, there is temperature control (maximum - +50 °C), indication, a mounting kit and a shower head with a flexible hose are included.

Place #5 – Timberk

Swedish company Timberk, which produces several series of inexpensive instantaneous water heaters. The Primalux and Watermaster lines are popular. The devices are not demanding on water pressure, have compact sizes and a modern design.

Model Timberk Primalux WHEL-7 with a power of 6.5 kW, designed for showers. Productivity – 4.5 l/min; water protection class – IPX4; has three power levels and a fine filter

The listed models are popular in Russia and are available in many online stores. Prices may vary depending on the exchange rate and the marketing concept of the selling company.

Conclusions and useful video on the topic

Some useful tips presented in the videos will help you make your choice.

The subtleties of choosing a instantaneous type of water heater are discussed in the following video:

Useful information about the design and operating principle of instantaneous water heaters:

Power calculation options:

Review of the Timberk Watermaster series:

As you can see, the choice of instantaneous water heaters is quite wide. Before purchasing, decide on the power, consider models from different manufacturers, inquire about the availability of additional options and purchase the device that best suits your requirements.

If you have any questions, please contact your sales consultants and carefully study the instructions.

Please comment on the material we have submitted for consideration in the block below. Here you can ask a question, as well as share your personal experience in choosing and operating an instantaneous water heater.