Hygienic domestic hot water heating with modern stratified storage tanks

Domestic hot water heating by ratiotherm

Meeting the requirements at hand

Heating systems must often perform two entirely different tasks in the household. On the one hand they provide the heat required to keep rooms pleasantly warm; on the other, they heat fresh water – for bathing, showering, cooking and drinking.

To heat drinking water, sufficient energy must be provided on the primary side. As a rule, the heat source does not have enough power to supply the required energy in the short term. This is why, ideally, stratified or buffer storage tanks are used here. They serve primarily as energy storage. The heat is stored not in the drinking water, but in the heating water.

Fresh water for human use should always be heated shortly before it is used to keep it safe and, most importantly, hygienic. At the same time, one expects that the water is available immediately, if possible, at the desired temperature. Die Oskar° drinking-water and cascade heater modules optimally meet all these requirements, for small and large systems alike.


Modern domestic hot water heating systems

A hygiene-relevant solution

Fresh-water technology and modern drinking-water heating systems have not only established themselves in the field of single-family homes. Especially in the commercial-property sector, drinking-water heating stations permit decoupling of hygiene requirements from energy-intensive measures. Energy storage in the Oskar° stratified storage tank is removed from the hygiene-relevant drinking-water area and relocated to the heating side, where it can occur at any temperature. This enables energy-efficient plant systems that not only meet the requirements of the Drinking Water Ordinance but are also appealing for the new planning freedom available through high solar yields.


Domestic hot water heater by ratiotherm

The optimum solution

Hygienic drinking water heating based on the continuous-flow principle

Focus on clean water

Ordinarily hygienic domestic hot water heating based on the continuous-flow principle is performed through the heating system. For this, it must have two circuits: one to deliver heat to all rooms of the house, and a second to provide water for drinking, cooking and personal hygiene.

The greatest hazard of water contamination is ‘standing’ supplies of domestic hot water, as they were once found in boilers – and to this day sometimes still are. For example, if fresh water is used for heat storage, in old boilers, an invisible humid biotope is created in the bottom area of the boiler which one would rather not want to have in the house.

This is the ideal location for bacteria such as the life-threatening legionella bacteria, or the different types of fungi which may also be harmful to health. Heat-exchanger systems that work on the principle of a continuous-flow heater solve this problem and are the optimal solution for hygienic domestic hot water heating.


Legionella-free drinking-water heating

with modern systems

In principle, the most sensible solution for hygienic drinking water heating is a continuous-flow heater. It generates domestic hot water when needed. Cold water flows through pipes where it is heated and then discharged through the tap. Small, compact appliances, usually installed directly in the kitchen or in the bathroom and powered by electricity, do the job well. However, they have the disadvantage that they require a high energy input and increase consumption costs accordingly.

Relief can be provided here with a system that e.g. can also be operated with a solar system, and a stratified or buffer storage tank for the heating system with domestic hot water heater. When hot drinking water is requested, it is heated via a heat exchanger using the continuous-flow principle. So, already existing, and ideally free, solar-generated heat is used, rather than first use costly electricity to generate heat – as is done with compact equipment.

At the same time, all the hygiene requirements are met, as the cold water is heated only when needed and only in the amount needed. With powerful, modern drinking-water heaters, the flow rate can be continuously regulated as well. They also offer the possibility of cascading, with several of these systems combined into a single unit and made suitable for even large consumers.


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