Hot water tanks, Temperature and Legionella
I have a 300 litre unvented water tank. Heated primarily from an air source heat pump but later we intend to install solar PV with excess power heating the tank via the immersion heater.
The reason for the large tank is to enable hot water to routinely be stored at the lowest usable temperature as heat pumps are not good at heating water very hot.
The sweet spot I have arrived at is a target water temperature of 48 degrees. The heat pump has a built in hysteresis so does
Perhaps a bit of a basic point, but this is a sealed system, isn't it?
If so, then there's no way any airborne bacteria, like legionella, will be able to get into the hot water tank.
It's different for a vented hot water tank, as it's possible for legionella to get in via the fairly open cold water tank that fills it, which is why you need to periodically heat up the hot water tank to kill anything off. I can't see the point with running an anti-bacterial cycle on a seal
