Water heater or boiler – which is better?

Running hot water is no longer a luxury. Every household has a water heating system, but there are different techniques for producing warm water. Households that are not connected to the central hot water supply need a boiler or instantaneous water heater. In times of high energy costs, the question arises, which of the two household appliances deals more efficiently with the required energy and whether the consumer can save money, because energy saving in the home should not be taken lightly.

Instantaneous water heater: cheaper space saver or slower water heater?

Table of Contents

  • 1 instantaneous water heater: inexpensive space saver or slower water heater?
  • 2 gas water heaters save money
  • 3 Boiler: Inefficient energy eater or fast hot water supplier?
  • 4 products from Amazon.de
  • 5 Conclusion – water heater more efficient

Instantaneous water heaters the water, as the name describes, during the run. For this purpose, the device lowers the water pressure and reduces the amount of water to be heated. Since hot water is always available in unlimited quantities with a water heater, it is especially recommended in rooms where you consume a lot of warm water.

Electric instantaneous water heaters pass water through pipes that have heating coils inside. They are connected to the three-phase three-phase network like an electric stove, which is why only a specialist should carry out the installation.

Small water heaters operate with a connected load (current consumption) of 3.5 to 6.5 kilowatt hours and are designed for single taps and smaller amounts of hot water. Larger units that provide warm water, for example for an entire floor, have a connected load of 18 to 33 kilowatt hours. In general, the higher the connected load, the more warm water will be available in less time.
For a water heater with electronic control, the desired temperature can be set on the unit. The addition of cold water is eliminated and the efficiency is thereby increased. Electronically controlled instantaneous water heaters consume on average 20 percent less electricity than those without electronic control. The problem with DHW heating with electricity is the low efficiency of the electricity. Since its production generally causes an energy loss of about 75 percent of the energy used (coal, oil), the cost of a kilowatt hour of electricity is around 20 cents. Assuming an average consumption of 150 kilowatt hours per year, this results in costs of around 30 euros.

With older devices, it may happen that a constant temperature is not guaranteed. This is particularly unpleasant in activities such as showers, as the water can become boiling or ice-cold within seconds. In general, however, consumers should also see the advantage that with instantaneous water heaters, the water is always fresh and is not stored as in boilers for a long period already in the store. Prior to installation, a specialist must check whether it is even possible to connect the instantaneous water heater, as it requires quite a bit of electricity when heating the water.

Gas water heaters save money

Water heater is also available with gas operation. Particularly inexpensive is the hot water by means of a gas boiler. The low energy loss of the gas reduces the price of the kilowatt hour to nine cents. This results in annual operating costs of about 13.50 euros (150 kilowatt hours). When questioning the location, it should be noted that gas-powered instantaneous water heaters are larger than their electric counterparts and can not be installed quickly with the cordless screwdriver.Here the expert has to "move out", especially since private people should better keep their hands off the connections.

Boiler: Inefficient energy eater or fast hot water supplier?

Boilers heat water up to 100 degrees Celsius for a long period of time and keep it warm through constant heating and insulation. Thus warmed up water is stored permanently. In the hot water tank is differentiated between different forms: the hanging storage, the small storage and the sub-table storage.

This technology requires much more power than a water heater because the water is permanently heated, so that the user is supplied with uniformly warm water immediately after opening the faucet and not wait for a preparation. Small water reservoirs are often operated electrically; larger models also with gas. A sensor tube, which is responsible for the temperature control, is located next to a switch, with which the user can adjust the temperature. Temperature sensor and heating element are housed in a vessel made of copper or plastic. In pressure boilers, the vessel is made of stainless steel sheet. Cold tap water flows into this vessel, which is then heated to the desired temperature.

Preferably for the supply to sink electrically heated hot water storage are used with a minimum of five liters of water content. These are needed if there is no central hot water supply or the central heating is too far away from the room where a hot water connection is needed. Even if water pipes that are too widely branched or hardly used are available, experts recommend the use of a hot water storage tank, since these circumstances are not only energy-impractical, but also hygienically problematic.
The average annual consumption of a boiler is at least 500 kilowatt hours. Multi-person households must expect a consumption of 600 to 800 kilowatt hours. This results in annual costs of at least 100 euros. The boiler thus exceeds the costs of a water heater enormously, as it heats the water only when needed to the required temperature. Another disadvantage of the boiler is that high waiting times can occur when the memory is empty. For example, if the user fills his bathtub with warm water, he may need to wait a while for the boiler to warm enough water for dishwashing. To prevent this from happening, you should – if possible – install a boiler with enough space. As a rule of thumb: 50 to 60 liters per person. In a four-person household, the boiler must therefore be able to store 200 to 250 liters of water. Larger memories with up to several thousand liters of storage space are mainly used for apartment buildings.

The ideal hot water temperature is between 55 and 60 degrees Celsius. This is sufficient to have enough water available and still keep the radiation losses of the boiler in order to save electricity.

Conclusion – water heater more efficient

Even if the power requirement of a water heater at the moment of hot water production is considerably higher than that of a boiler, the annual average power consumption is lower. The constant power consumption of a boiler throughout the day justifies this fact. As an alternative, solar systems for hot water would offer. These are considerably more expensive to purchase, but in the longer term cover the acquisition costs and produce almost free electricity for hot water from then on.