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Before you spend Saturday evening on the couch or go out with friends, you like to treat yourself to a long bath in the tub. With a water heater, you can heat the water in your apartment even without a hot water connection and can relax and enjoy your full bath at the right temperature. In the following guide, you can read what else water heaters are suitable for, how the models differ and how you can find the right device for you.

Obtain warm water from the cold water pipe

If you only have a cold water connection, be it in your home, garden, workshop or allotment, a water heater is a valuable service. It can be used to heat cold tap water to temperatures of up to 100° C. Some models can be used to heat up water for a short time for a specific purpose such as showering or washing dishes, or to keep it warm for continuous use. Water heaters are usually connected between the pipe and the tap, so that the temperature can be regulated directly with the mixer tap . This means that the water comes out of the tap at the desired temperature – just like with taps with hot and cold water connections.

Continuous or storing – model variants at a glance

As a rule, hot water devices are equipped with a power connection to heat the water using electricity. The main difference between the models is the way in which the water is prepared.

Instantaneous water heater

An instantaneous water heater heats the water during use. Such devices are very powerful in order to bring the flowing water to the desired temperature immediately. Since the warm water comes out of the mixer tap as soon as you turn on the tap, the instantaneous water heaters are practically indistinguishable in their functionality from a faucet in the bathroom or kitchen with hot and cold water connections.

Boiling water devices

Boiling water devices produce hot water at temperatures of up to 100° C. Such models, which are also known as boilers , heat a certain amount of water when required and are therefore usually not insulated. The devices have a capacity of up to 5 l and are particularly suitable for decentralized use, for example to preheat the water for your shower or bathtub. Boilers are available from €160 to €250.

Storage

Storage tanks are constantly filled and keep a certain amount of warm water in reserve , which is why they are usually thermally insulated to work energy efficiently. There are different versions, which are referred to as small, under-counter or wall storage tanks depending on their design. Like boilers, storage tanks are also able to reach temperatures of up to almost 100° C.

What is important when buying a water heater

The most important criteria when choosing the right device are the volume and performance of the model, because this determines how much water you have available in what time.

temperature

Instantaneous water heaters heat the water to temperatures between 30 and up to 75° C. For some models, the maximum is around 40° C, which is sufficient for activities such as washing dishes and showering thanks to the flow principle. Boilers and storage tanks create higher temperatures up to the boiling point, so that you can mix the heated water with the cold water from the tap before use and therefore need less hot water.

Capacity

The volume is an important criterion, especially for boiling water devices and storage tanks, as it defines the amount of water available. The capacity is between 3.5 and 80 l. If you need more hot water, another heating process is necessary, which takes some time. With instantaneous water heaters, the capacity is not really important; the maximum flow rate is what matters. It is between 1.9 and 11.6 l per minute.

Heating performance and energy efficiency

The rule of thumb is: the faster the water needs to be heated, the more power is needed. That’s why instantaneous water heaters usually have a particularly high output. Boiling water devices and boilers take a little time to heat up. They are therefore particularly efficient, although storage tanks require additional power to keep them continuously available. The output values are between 3.5 and 27.0 kW for instantaneous water heaters, while boilers and wall-mounted storage tanks have 2.0 to 6.0 kW. The devices need between 12 and 185 minutes to bring the water to maximum temperature. Most devices belong to energy efficiency class A, some are in category C.

Size and installation type

The dimensions are particularly important if you have a fixed place in mind for your model. There is usually only limited space available for built-in appliances, for example those that are installed under the kitchen sink or above the bathtub. The size of the appliances varies in height, width and depth between 13 and 47 cm, 14 and 29 cm and 8 and 15 cm. In addition, the question arises whether you want to hang your appliance on the wall or install it somewhere else.

Conclusion: Heat water for use easily and effectively

Showering and bathing, doing dishes or simply washing your hands? Depending on what you primarily need your device for and how much water you need for it, the model type you are best advised to choose depends:

• Instantaneous water heaters continuously supply hot water that is heated as it is used. As soon as you turn on the tap, warm water of up to 75° C comes out of the faucet.
• Boiling water devices heat tap water to up to 100° C and use a tank with a volume of up to 5 l. When you need hot water, you start the boiler and shortly afterwards you have a certain amount available.
• Wall-mounted storage tanks keep water warm in reserve, reaching temperatures of almost 100° C. These devices, with a capacity of 5 l, are usually insulated to be particularly energy efficient.