These heaters heat the cold tap water directly using a heating coil or heating rod and then temporarily store it. Hot water storage heaters are, so to speak, heat generators and thermal stores at the same time. Hot water storage heaters run on electricity. The required temperature for a hot water storage heater can be set either electronically/electrically or manually. In both cases, a connection to the existing heating system is not required. Wall mounted storage water heaters from Viessmann can be operated in single-circuit, dual-circuit or once-only mode. Their output is between 2 and 6 kW.
Vitotherm
Electric wall mounted storage water heaters and small electric storage water heaters
They are suitable for both individual and group supply of domestic hot water.
Vitotherm EW6 electric wall mounted storage water heater
Vitotherm electric wall mounted storage water heaters and small electric storage water heaters
Domestic hot water can be produced and stored in different ways. One way to combine both functions in one appliance is to use electric wall mounted storage water heaters and small storage water heaters.
Small storage water heaters are usually DHW cylinders with a small capacity. They only need a 230 V socket for operation. Small storage water heaters such as the Vitotherm ES2 and Vitotherm ES6 are designed to supply domestic hot water in rooms with low DHW demand. Possible points of use are hand basins, utility sinks and kitchen sinks. These compact appliances supply individual draw-off points with DHW reliably and efficiently.
Wall mounted storage water heaters work differently. These hot water storage heaters are also electrically operated, but are able to supply multiple draw-off points with domestic hot water. Possible points of use are not only kitchens but also bathrooms with a high DHW demand. With a capacity of 80 litres and above, these appliances have enough in reserve for a bath. Vitotherm electric wall mounted storage water heaters and small electric storage water heaters can heat water up to 85 degrees Celsius. Customers frequently require this, especially in the kitchen area. Hot water storage heaters generally all function in a similar way, whatever their design.
How electric hot water storage heaters work
It is not uncommon for DHW cylinders that are electrically operated to be called electric hot water storage heaters. This is only partly correct. Experts draw a distinction between direct and indirect hot water storage heaters.
In addition to hot water storage heaters that run on electricity or gas, indirect hot water storage heaters are also available. These do not heat the water themselves, but only store the domestic hot water indirectly heated by the boiler. They are therefore dependent on the existing heating system. On the other hand, they achieve a higher overall efficiency compared to electric hot water storage heaters. In order to prevent germs developing, the stored water must be constantly above 60 degrees Celsius. Alternatively, homeowners can heat the water to this temperature once a day to maintain the required protective function.
Last but not least, there is a further distinction between non-pressurised (vented) and pressure-dependent (unvented) operation. With a non-pressurised appliance such as a small storage water heater, cold water only flows into the storage water heater when hot water is drawn off, forcing the water that has already been heated upwards. It is therefore independent of the cold water system pressure. Non-pressurised hot water storage heaters have only one draw-off point. If several draw-off points are to be supplied with DHW, pressure-dependent electric hot water storage heaters are required. These are constantly connected to the water supply and are therefore under pressure at all times. For this reason, these appliances are very sturdily built and can withstand much higher pressure than their non-pressurised counterparts.
Product overview
Below you will find a selection of the Vitotherm product range with the relevant key data. Further information on the individual products is available in the Technology brochure – Electric heating systems (PDF, 656 KB) and in our ViBooks database in the datasheets.
Vitotherm EW4 and EW6: wall mounted storage water heaters with up to 150 litre capacity
The Vitotherm EW4 and EW6 wall mounted storage water heaters are designed for installation in bathrooms and utility rooms. With a cylinder volume of up to 150 litres, appliances with a capacity of 80 litres and above have sufficient reserves for a bath. Multiple draw-off points can also be supplied –– for example a washbasin and shower at the same time. If required, the quick heat-up button is activated. The temperature is continuously and precisely adjustable to between 35 and 85 °C. The Vitotherm EW4 is equipped with an electronic keypad and the EW6 with a rotary selector.
Energy efficiency classes:
- Vitotherm ES2/ES6 small storage water heater: A
- Vitotherm EW4 wall mounted storage water heater: A (A30,) B (A50/80)
- Vitotherm EW6 wall mounted storage water heater: B (A30), C (A80/100/150)
Vitotherm EW4 with maintenance-free impressed current anode and self-learning PCB
Eco functions for high efficiency
Three adjustable eco functions help the Vitotherm EW4 to run efficiently and economically:
Eco Balance
This operating mode offers the highest level of DHW convenience at all times. The set temperature can be manually adjusted between 61 and 85 °C. If the appliance detects that less water is drawn off over the course of a week, it automatically reduces the set temperature to 60 °C to save energy.
Eco Efficiency
The appliance does not automatically heat up to the set temperature of 60 °C until 40 percent of the cylinder content has been drawn off. This operating mode offers additional energy savings.
Eco Energetic
In ECO Energetic mode, the appliance analyses the draw-off times and volumes for one week. The following week, it is able to provide the right amounts of mixed water. This energy saving mode is optimal if DHW is drawn off at the same time each day, for example before work or school. If the draw-off times change, for example during a holiday, the Vitotherm EW4 automatically adjusts to the new consumption pattern.
7-segment display indicates the operating status
All basic settings only need to be entered once directly on the digital user interface and then remain stored. Furthermore, the backlit display shows the available volume of domestic hot water, the energy consumption, the required temperature set at that time, and various values relating to the current operating status.
Product cross-section Vitotherm type EW4
Vitotherm EW6 with protective magnesium anode and infinitely variable temperature adjustment via rotary selector
Vitotherm ES2 and ES6: small storage water heater with savings potential
With a cylinder volume of five litres, the Vitotherm ES2 and ES6 small electric storage water heaters provide a rapid supply of domestic hot water in kitchens and offices. The non-pressurised appliances with a 2 kW output simply require a 230 V socket for connection.
Both storage water heaters are equipped with the Thermostop function, which cuts electricity bills by up to €30 a year. The ES2 model also features an anti-drip function which prevents water dripping when it is being heated up. Besides reducing water consumption, this also prevents limescale deposits.
The Vitotherm ES small electric storage water heater with a volume of five litres for decentralised DHW provision
