Bath and shower
Instantaneous water heater at Warentest – cheap to buy but extremely expensive to run
When you have a shower with a tankless water heater, the electricity bill is no fun.
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Warentest has tested electric instantaneous water heaters: They cost little and produce warm water reliably. The days of temperature fluctuations are over. However, the electricity costs spoil the joy of the shower.
Tankless water heaters don’t have the best reputation. The devices were once chronically unreliable and reacted sensitively to pressure fluctuations. When the toilet was flushed, the water in the shower suddenly bubbled. This no longer happens today, the product testers assure us.
Six out of nine devices were good; they reliably deliver water at the desired temperature. Even if they are only called “electric” but not “fully electric”. Fully electric means that the device can not only control the power, but also regulate the amount of water.
Cheap to buy
The second good news: There are good devices starting at 300 euros. The fundamental problem, however, is the operating costs, because the instantaneous water heaters also heat the water Electricity is known to be very expensive in Germany. The test household incurs around 200 euros in electricity costs per year. For warm water in the bathroom and kitchen. The differences between the devices are minimal.
The testers particularly recommend three devices: The electronic Clage DEX Next (590 euros) achieved a good grade of 2.0. It heats quickly and accurately and is easy to use. The Clage DSX Touch achieves the same marks. The otherwise identical model is fully electronic and 300 euros more expensive: it costs 890 euros. It is also cheaper, the Viessmann Vitotherm EI4 (2.5) is available for 300 euros; it only has a rotary control instead of a display.
To understand the stated costs, you have to read the fine print. The consumption refers to 41 liters of hot water for washing hands, washing dishes and showering every two days – for one person. If you shower more or longer, consumption and costs increase. The same applies if there are several people in the household.
Only recommended for special cases
What are the advantages of an electric instantaneous water heater? Such devices are also available with gas operation, so the energy costs are significantly lower. However, purchase, installation and maintenance are significantly more expensive. There must be an exhaust ventilation option and a gas connection. The electrical devices only require a three-phase power connection, but you cannot simply plug them into the socket. Why were they installed? It used to be the easiest way to supply small, subsequently installed bathrooms with hot water. The alternative was an electric boiler, but then you had to accommodate the storage container with the warm water.
Today, an instantaneous water heater is only interesting if there is no independent heating system in the property. The instantaneous water heater is also worthwhile if warm water is only needed very rarely – for example in a guest bathroom. It is also used for subsequently converted granny flats when it is important to keep the installation effort down.
The magazine’s environmental tip is correct, but also a bit gaga: “If you can, you should prepare hot water using effective methods such as solar panels or heat pumps, instead of directly with electricity. This saves CO2.” Every installer knows this. Even if conventional heating systems provide hot water, it will be cheaper. You only use an instantaneous water heater if you don’t have these options.
You can do the entire test for a fee here see.