Gas or heat pump in a KfW55 house

We don’t have a pump either (all pipes under 3 L) Regular water extraction is actually everywhere except the bathtub – but the branch line comes off the upper floor bathroom and is 1 m long. Just started the legionella program and turned on the heating element – heated the water up to 75°C. Then I read that you also have to open all the taps every 3 minutes... then the temperature dropped drastically -. - The experiment cost 1.5 €. But well – you can probably do that every 3 months.

Yes, that’s the trick. Heat up. Then open all hot water taps you have at “full throttle.” It takes me less than 10 minutes until the hot water is “gone.”

Regarding the costs: Actually not a big deal.

And 75 degrees of course is more than enough. Then the critters are pasteurized. They thank you by dying.

If you do this regularly (as I said, I have a calendar entry, do it at least once a month from November to March, and again in April this year), you don’t have to fear legionella anymore (on the contrary: the legionella fears the homeowner, that’s how it should be).

Best regards Thorsten

PS: Thanks for confirming my suspicion that heat pumps also have such a program.

PS: The whole thing only really started when everyone became totally obsessed with saving due to exorbitant energy prices. Me too. I admit it openly.

Back in my father's time, that was hardly ever an issue. Our hot water ran at 80 degrees. Phew. The scale buildup... well. At 67 the hysteresis ended, the burner (35 kW! or was it even 38? My goodness... nowadays that’s enough for 3 houses) roared and hissed to life, and a few minutes later 250 liters in the tank were back at 80 degrees. Every legionella escaped from there. One by one. On foot. Another advantage: you could usually brew coffee or tea with tap water. grin.

I'm not so sure about my geothermal heating anymore, maybe the gas heating would have sufficed after all.

I'm not so sure about my geothermal drilling anymore, maybe the gas heating would have done after all.

I envy you. The geothermal drilling is absolutely brilliant.

We couldn't do that here. It wasn't possible. It was said right away when selling the property.

I didn't want an air-to-water heat pump.

Groundwater heat pump was also not an option – groundwater is far, far away...... burying 300 sqm of surface collector on the property with Bergisches schist underneath: financially not a great idea....

A friend / colleague of mine also has geothermal drilling. In the long run, over 20 years, it definitely pays off. He operates with a COP of 5.7 (plus 6.3 kWp photovoltaic system facing south) – when I see his heating costs for a house almost twice as big, it brings tears to my eyes. He doesn't pay more than 20 euros per month.....amazing.

We are not there at all... Hot water annual performance factor is 3.7; for heating between 5.2 and 5.6... well, the first winter still has to come. Monthly it will probably be around €50 for us... also okay and no reason to panic and, by the way, also as calculated.

Monthly it will probably be about 50 € for us... also okay and no reason to panic and besides also as calculated.

It's also no reason to panic.

50,- per month is certainly not the problem, all other things are much more expensive.

Furthermore: You are heating very environmentally friendly and are thus part of the energy transition. Great. As I said, I envy you, I would also like to have something like that (just not an air-to-water heat pump, no one has been able to really convince me of these devices so far).