Anti-legionella cycle

The anti-legionella cycle regularly heats the hot water cylinder to a higher temperature to kill off germs. You can clarify with your installer how often this is useful.

Legionella are bacteria that can multiply in warm, stagnant water. They are particularly dangerous when inhaled as a fine mist while showering. Many heat pumps therefore have a Legionella protection cycle: the cylinder is heated to a higher temperature at fixed intervals to kill off germs.

What applies to detached houses

• The klimaaktiv Wegweiser (guide) refers to the Trinkwasserverordnung (Drinking Water Ordinance): temperature ranges between 25 and 45 °C, which promote the growth of pathogens, must be avoided. It specifies 55 °C as the target temperature before the tap.
• The stricter hygiene standard for larger buildings (formerly ÖNORM B 5019, currently ÖNORM B 1921) requires, according to the guide, over 60 °C at the cylinder outlet and at least 55 °C in the pipes; detached and semi-detached houses are exempt.
• The klimaaktiv Ratgeber Warmwasser (hot water guide) states that an outlet temperature of at least 50 °C must be achievable in single- and two-family homes.

Balancing efficiency and hygiene

Every extra degree in the cylinder costs money: according to klimaaktiv, heat losses increase by an average of around 1.6 % per degree. Short, well-insulated pipes without continuous circulation are the best prevention, as less water stands for long periods. After a holiday, klimaaktiv recommends heating the cylinder to over 60 °C once and flushing the pipes for a few minutes.

It is best to agree with your installer during handover how often and to what temperature your Legionella protection cycle should run.

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