Gas condensing boiler underfloor heating - time setting hot water

Hello everyone,

we heat with a gas condensing boiler with solar thermal for hot water preparation, underfloor heating. Since we haven't had a heating instruction yet and opinions sometimes differ, I have a few questions. We both work full-time and are not at home from 8 am to 5 pm. Hot water is needed on weekdays in the morning for 1 hour and then from 5 pm to 10 pm. Is it sensible to control the system intermittently or not? I've already heard different opinions and would like to hear yours. The solar thermal system should of course heat up when the sun is shining, but should the gas heating also warm the water on cloudy days, during times when we are not at home? And what about the required temperature for hot water, is 45 degrees enough or does it have to be set to 60? Questions upon questions^^ Maybe you can help me.

Theoretically, of course, a little energy can be saved if the water is not heated when it is not needed. However, modern buffer tanks are so well insulated that the savings will be at a very low level. If you have a circulation line, it will be more effective to turn off the circulation during these times. In practice, however, it is the case that one is sometimes unexpectedly at home and, for whatever reasons, also showers at different times of the day. Do you remember every time beforehand to switch the hot water preparation?? And then you stand under the lukewarm shower. That’s not really fun. The temperature of 45° is completely sufficient. Yes, yes – the dreaded Legionella.

Yes, the legionella! Bacteria that did not only appear in the 19th century, not only in third world countries, and did not only cause mild illnesses that put you out of action for 2-3 days. Just google it and decide for yourself whether 60 degrees is not the safer option.

Our system heats up to 75 degrees once a week. This is set by the manufacturer due to Legionella prevention. I thought this was the case with all modern heating systems?

Sylvia

Hello Sylvia,

Our system heats up to 75 degrees once a week. This is set by the factory for legionella prevention. I thought this was the case with all modern heating systems?

This is "only" the case with older systems. The latest generation (which we also install) no longer needs this heating because the hot water is heated via a stainless steel corrugated pipe while passing through the heat storage tank.

Best regards from the Rhineland

First of all, thank you very much for your answers! Since there is obviously no internet in the new house yet (ah), sorry for the late response. , does this new technology ensure protection against legionella or do you still need to heat to a higher temperature once a week? And what would you say, is a "time setting" for hot water worthwhile or not? , thanks for your contribution as well. Surely you are not entirely wrong, but such situations really occur very rarely with us. During vacation times etc., you could also set a different regulation then. I would be interested in the approximate range of savings. Especially when you have no experience yet, since it is a new building, you are a bit anxious about the first bill and want to do everything possible to make it "positive". Yes, yes, it's all exciting.