Instantaneous and storage water heaters: selection and installation

Recommendation points

• Features of the device of instantaneous water heaters
• Fundamental differences between storage water heaters
• Installation of instantaneous water heaters
• Installation of storage water heaters

If, besides electricity, there is no other way to heat water, you will have to choose a suitable electric water heater. In this article, we will give a comparative overview of popular models, tell you about the differences between different types, give recommendations for installation and maintenance..

There are two main types of electric water heaters. Some have a cylindrical container with water, the water in which is heated by a conventional heating element. They serve for a long time and are relatively easy to repair, but rather bulky.

More compact flow heaters, in which water is heated in a narrow heat exchanger using heating elements or an uninsulated spiral. Such devices are difficult (and sometimes impossible) to repair at home. Their use is often temporary, especially for residents who are firsthand familiar with the problems of a temporary lack of hot water supply. Instantaneous water heaters are slightly cheaper and more economical than storage water heaters, but due to their high power, they require a serious approach in organizing the supply network.

Features of the device of instantaneous water heaters

Control in instantaneous water heaters can be performed by a mechanical regulator or an electronic unit. In the first case, the power stages of the heating elements are switched, which is acceptable if the water heater is located near the point of draw-off. But this is completely inconvenient if the device supplies water to several points in the house; in such cases, electronic control is used. The unit regulates the temperature literally on the fly, some models have functions for presetting temperature modes or, for example, control from a remote control.

Inexpensive heaters have one or more heating elements, which are placed inside a small metal or plastic bulb. The scourge of this design is the abundant formation of scale on the heating element. However, it can be quite simply replaced.

In open-coil flutes, the latter is placed inside a sealed copper tube. The heating of water in them is a little faster, no scale forms on the spiral. But such a heating element is very sensitive to air locks and bubbles. In the event of a breakdown, this unit changes entirely, but it is by no means cheap.

Powerful heaters require high pressure and flow to keep the heating element from overheating. But there are also open (non-pressure) flow pipes that can operate at low pressure. They are able to provide only one tap point with water, so they are immediately equipped with a shower diffuser with a flexible hose or gander.

Closed water heaters have a pressure relief valve and can be used to supply multiple taps. They are more expensive, so only for a shower or kitchen sink they buy non-pressure models.

Comparison of models of instantaneous water heaters

Model	ATMOR BASIC 3.5	ZANUSSI 3-Logic 5.5-TS	ELECTROLUX SMARTFIX 2.0 5T	Stiebel Eltron 18 SL	AEG DDLT LCD
A type	Open	Open	Open	Pressure head	Pressure head
A heating element	2 independent heating elements 220 V	Combined copper heating element 220 V	Open coil in copper coil 200 V	Open spiral in a pressure-resistant flask 3ph 380 V	Heating block with open coils 3ph 380 V
Control	Mechanical thermostat, 3 heating stages	Fully electronic, 3 heating stages	Mechanical thermostat and flow sensor, electronic controller, 3 heating stages	Microprocessor-based, outlet temperature	Microprocessor-based, outlet temperature
Heating temperature	Up to 65-70 ° С	25-50 ° C	Up to 65 ° C	20-60 ° C	30-60 ° C
Power consumption, kW	1.5 / 2 / 3.5	3 / 3.5 / 6.5	Max 5	18	27
Productivity, l / min	3	3.7	4	9.2	ten
Dimensions HxWxD, mm	185x300x110	135x270x100	135x270x100	478x225x105	485x226x93
Additionally	Shower head, automatic on and off, overheating protection	Shower head or gander, overheating protection, flow sensor, 1 class of protection against electric shock	Gander, protection against overheating and scale, safety shutdown, flow and pressure sensors	Up to five remote controls, smart home connection, free installation, built-in airlock protection, preset modes, LCD display	Remote control, self-diagnosis, protection against air jams
Price	2 300 rub.	RUB 3,000.	2400 rbl.	63,500 rubles.	45,000 rubles.

Fundamental differences between storage water heaters

Unlike instantaneous, storage water heaters have a simpler device. Their tanks are made of stainless steel, sometimes coated with a sputtering of ceramics or silver. In compact boilers, there are several tanks and they are installed in a row to reduce the depth. Tall but narrow tanks are specially designed to be installed in the corner of a bathroom or in a closet.

The tank is insulated with polyurethane foam or more innovative materials. If it is of high quality, the water temperature remains up to two days..

The tanks use ordinary heating elements with an isolated spiral. The heating element can be placed in a flask filled with quartz sand. Such heating elements are called dry, they serve longer than usual.

Cold water is injected at the bottom of the tank and the bowl-shaped diffuser prevents mixing. Hot water is drawn from the top. The location of the tank can be either vertical or horizontal. There are also pressure storage water heaters with top water supply on the market.

Almost all heaters have a magnesium or titanium anode, the task of which is to prevent the formation of scale on the heating element and, taking the influence of salts in the water, to protect the tank from corrosion. The service life of the anode is from six months to three years.

Heating temperature is controlled by a mechanical thermostat or electronics, the latter has higher accuracy and additional functions.

Like instantaneous water heaters, tanks can be open or closed. The former are less common; only one draw-off point can be connected to them. The main advantage of this design is the ability to drain water even in the absence of pressure in the supply line.

Comparison of storage water heater models

Model	ZANUSSI ZWH / S 30 Symphony HD	Thermex ID 80 H	Stiebel Eltron PSH 80 Universal EL	Ariston ABS Pro 15 OR	Atlantic Steatite Exclusive VSRS 200L
Volume, l	thirty	80	80	15	200
power, kWt	1.5	1.3 / 2	3	1,2	2.4
Control	Mechanical adjustable	Electronic	Electronic	Mechanical	Mechanical
Heating element type	Wet	Wet	Dry ceramic	Wet	Dry ceramic
Accommodation	Vertical	Horizontal	Vertical / horizontal	Vertical	Outdoor vertical
Max. temperature	75 ° C	75 ° C	85 ° C	75 ° C	65 ° C
Heating rate	68 min to 75 ° C	130 min to 45 ° C	130 min to 60 ° C	45 min to 60 ° C	285 min to 65 ° C
Tank type and shape	Cylindrical steel tank with glass enamel coating	Several stainless steel tanks in a rectangular case	Cylindrical CoPro coated steel	Rectangular welded enamelled steel tank	Cylindrical steel coated with antibacterial enamel
Dimensions HxWxD, mm	625x385x385	493x1025x270	893x475x475	360x360x300	1258x575x598
Empty tank weight, kg	14.8	22.8	34	7.4	58
Additionally	Magnesium anode, operation and temperature indication	Magnesium anode, overheat protection, LCD display, stylish design, safety shutdown, drain connection	Magnesium anode, three operating modes, accelerated heating, frost protection	Magnesium anode, water mixing protection	Magnesium anode, safety valve, heavy duty enamel
Price	6 600 rub.	18,000 rubles.	41,200 rbl.	RUB 5,700.	22,000 rubles.

Installation of instantaneous water heaters

Flow-through heaters are attached to the stone wall with quick-assembly dowels, and to the gypsum plasterboard wall – with a mol-type mounting element. Strictly follow the recommended installation direction, most heaters must not be rotated. Only heaters with a shell protection degree of at least IPX4 can be installed directly in the bathroom or shower..

The electrical connection must be carried out through an RCD, unless the protective shutdown is provided by the manufacturer. The device is connected with a three-core copper cable directly from the input housing panel, and if a protective conductor is not brought into the apartment – from the floor panel with mandatory grounding to the metal frame. Connection via a plug connector is not allowed, a circuit breaker with tripping characteristic “B” or a differential switch is used for switching.

Instantaneous water heater connection diagram: 1 – cold water supply; 2 – mixer; 3 – shut-off valves; 4 – check valve and coarse filter; 5 – RCD; 6 – introductory electrical panel

Non-pressure heaters have only one branch pipe available for connection – cold water supply. On pressure heaters, the nozzles are marked in blue (cold water) and red (hot water), or with inscriptions. For ease of dismantling, it is recommended to equip the supply pipes with ball valves.

Connection diagram of a pressureless water heater: 1 – from the cold water main; 2 – shut-off valve; 3 – automatic air vent; 4 – coarse filter; 5 – valve for adjusting the water pressure; 6 – gravity water heater

Installation of storage water heaters

Wall-mounted storage water heaters require reliable fastening. In solid concrete and brick walls, metal expansion anchors play the role of such. Walls made of cinder block or shell rock do not have sufficient density, therefore, when fastening to them, through pins or staples must be used. Fastening of tanks to walls made of gypsum plasterboard is allowed only through through fastening and only if there is a reinforced profile frame.

The electrical connection of the boiler is carried out through a difavtomat or an RCD, the basic requirements are the same as for a flow heater: a one-piece cable and grounding. As with instantaneous water heaters, the connection is made on the terminal block to the contacts L – phase, N – neutral conductor, PE – protective conductor.

Storage water heater connection diagram: 1 – water supply tap; 2 – bathroom mixer; 3 – mixer in the kitchen; 4 – safety valve; 5 – valve for air supply when draining; 6 – valve for draining the tank; 7 – RCD; 8 – introductory electrical panel

The boiler requires the mandatory installation of an overpressure valve. To drain water from closed boilers without pressure, both branch pipes are equipped with three-way taps or additional outlets with shut-off valves.