„Legionella circuit“

A periodic and temporary temperature increase to over 60°C in a hot water system is called a "Legionella circuit". However, according to DVGW W 551 (A) and W 557 (A), this is not a thermal disinfection. This measure is not effective anymore if Legionella is already present. It also leads to rapid calcification and wear of the fittings and seals; it contributes to the development of resistance of Legionella to ever higher temperatures.