Make sure to disable any existing Legionella cycle that’s already programmed in your heat pump controller. This avoids overlapping schedules, which can cause unnecessary hot water runs and wasted energy.
You can set a legionella cycle by scheduling a recurring set point at the maximum temperature once a week in the Havenwise app. The exact temperature to use varies on the brand of your heat pump.
Mitsubishi and Samsung: Schedule a set point of 55°C
Vaillant: Schedule a set point of 60°C
Why are some brands limited to 55°C?
Some models cannot achieve above 55°C reliably, including Samsung and Mitsubishi units. Going higher usually forces the immersion heater to switch on, which is very inefficient and costly.
What's different about those models?
It's the type of refrigerant used in the heat pump - any heat pumps using R32-based refrigerants physically cannot achieve the flow temperature required for tanks warmer than 55°C. Heat pumps using R290 can.
Do I even need a Legionella cycle?
Maybe not. Heat Geek have an excellent video discussing this: