The Plumbing Code of Australia (PCA) has two conflicting requirements. Prevent the growth of Legionella bacteria, the cause of Legionnaires’ disease, it is a strict requirement that any stored hot water be kept at minimum temperature of 60°C. The same code requires that the delivery temperature of hot water for personal hygiene purposes is not to exceed 50°C and in some institutes e.g. facilities for young, aged, sick or disabled persons, the maximum delivery temperature is 45°C for safety purposes.

In order to meet both of these requirements a tempering valve needs to be installed. The hot water tank maintains the 60°C strict requirement to prevent bacterial growth while the tempering valve with a temperature sensitive element allows cold water to flow with the hot water through the pipes delivering constant hot water temperature to your kitchen and shower taps. With this mechanism and design it maintains a constant outlet temperature, reducing the risk of bacterial infection and accidental scalding.