Hello.
It is often recommended to set the hot water temperature to 60°C (140°F) on the heating system when using a boiler (in our case, a 300L (79 gallons) unit with gas heating) as a precaution against Legionella bacteria. Since my family’s health is the top priority, I don’t mind that. What I don’t understand is whether the hot water should be maintained at 60°C (140°F) continuously for 24 hours, or if it is recommended to turn off the hot water preparation at night using a timer. If you switch it off at night, it seems somewhat inconsistent because the water would cool down again and drop below the recommended 60°C (140°F).
Do you have any opinions on this?
It is often recommended to set the hot water temperature to 60°C (140°F) on the heating system when using a boiler (in our case, a 300L (79 gallons) unit with gas heating) as a precaution against Legionella bacteria. Since my family’s health is the top priority, I don’t mind that. What I don’t understand is whether the hot water should be maintained at 60°C (140°F) continuously for 24 hours, or if it is recommended to turn off the hot water preparation at night using a timer. If you switch it off at night, it seems somewhat inconsistent because the water would cool down again and drop below the recommended 60°C (140°F).
Do you have any opinions on this?
Pädda schrieb:
Do you have any opinion on this? It is usually common to turn off hot water preparation at night. Why should that be common practice, and what would be the purpose? The tank keeps the water well insulated and warm.
Generally, maintaining a hot water temperature of 50°C (122°F) works well. You don’t really need it any higher. Legionella bacteria are not usually an issue in a single-family home. After a 2-3 week vacation, however, it is recommended to heat the water to over 60°C (140°F) once and then briefly open all taps.
Tolentino schrieb:
mh, tasty legionella shake.
If you’re very cautious, you could heat the storage tank to 70°C (158°F) once a week. Preferably with solar power at midday. Strictly speaking, you would then also need to open all the taps so that 70°C (158°F) reaches all hot water pipes.
I agree with the majority: usually unnecessary in a single-family home. I only heat my hot water to 48°C (118°F), and only during the day. Overnight, it might drop by 2 to 3 degrees—so much for the cooling issue.
As @kati1337 says, it is perfectly fine.
And with a heat pump, I would especially only turn on the domestic hot water production when hot water is actually needed. Otherwise, during the day, the hot water cools down slightly and the heat pump immediately turns on to reheat it, even though it’s unnecessary.
Hot water production with a heat pump is one of the least efficient processes.
And with a heat pump, I would especially only turn on the domestic hot water production when hot water is actually needed. Otherwise, during the day, the hot water cools down slightly and the heat pump immediately turns on to reheat it, even though it’s unnecessary.
Hot water production with a heat pump is one of the least efficient processes.
halmi schrieb:
Usually, you set it up according to your personal preference. When the kids take a bath in the evening, I don’t want to take a cold shower the next morning. I'm the same – efficiency is important, but I want to be able to take a warm shower any time of day or night if I feel like it. Our hot water is always kept at a high temperature. When the sun is beating down on the roof, we heat it a bit more because that's more economical than feeding the electricity back into the grid.
60°C (140°F) does not kill Legionella bacteria; it actually makes them more heat-resistant. So, it’s ineffective. Check out the pink forum—it’s full of discussions on this. You can safely skip a Legionella elimination program. Regular water exchange is usually sufficient. Personally, I rely on a fresh water system. This eliminates any standing warm water. The fresh water heats up the incoming water in a continuous flow process via a heat exchanger. However, this is somewhat more expensive than a simple water storage tank.
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