Heat pump and the scare about legionella

Hello everyone!

I haven’t found such contradictory statements on a topic online for a long time as on this legionella issue combined with modern heat pumps. Many people (including us) have set the hot water temperature quite low to save energy. Ours is set to 45°C, realistically it usually heats to 48-49°, and in summer, when surplus electricity comes from the roof, even higher. Our heat pump has an anti-legionella program, but our installer switched it off. He explained to me why, but I don’t remember anymore. Is that sensible? We currently have no problems, but of course, I don’t want to cultivate a legionella farm. We have a Tecalor THZ 504 with a 235L hot water storage tank. We have no dead taps in the house, we use all our faucets regularly. We also quite often empty the tank—at least when we bathe the child and then I bathe, I have had cases where I still want to run hot water and barely any comes out. We don’t have a circulation line.

Online you find everything, from people who dismiss the topic as complete scaremongering to people who predict the end of the world because of legionella. Where does the truth lie, especially: Should I raise my hot water target temperature from 45°C? and Should I switch on the legionella program of the heat pump, if yes, how often?

Best regards,
Kati

We have no dead draw-off points in the house; we use all our taps regularly. We also quite often drain the storage tank considerably – at least when we bathe the child and then I bathe afterwards, I have occasionally encountered the case where I want to run more warm water, and hardly anything comes out. We do not have a circulation line.

Then lean back and relax.