ᐅ Optimal Temperature for a 300-Liter Hot Water Storage Tank?

Created on: 22 Dec 2017 09:39
C
Curly
Hello,

We have a 300-liter (79-gallon) hot water tank and a gas heating system. The factory setting is 60 degrees Celsius (140°F), but our heating technician suggested that 50 degrees Celsius (122°F) would be sufficient. What about legionella bacteria? We certainly won’t completely empty the hot water tank (which supplies two showers). Our bathtub holds 220 liters (58 gallons), but it is used only occasionally. Is a temperature of 50 degrees Celsius (122°F) enough? What temperature do you keep in your hot water tanks?

Best regards,
Sabine
M
merlin83
24 Dec 2017 09:29
toxicmolotow schrieb:
70°C (158°F) cannot be achieved by a heat pump alone. Then the electric heating element has to step in.

Yes, that's the problem: Legionella bacteria simply don't adapt to heat pumps and only start to die off at water temperatures of 50°C (122°F) and above.
T
toxicmolotof
24 Dec 2017 09:45
Or size it so that Legionella bacteria have no chance at all. After all, a single-family house is not a swimming pool.
M
merlin83
24 Dec 2017 09:52
And we won’t go on vacation anymore because otherwise the water will go bad. Why not simply heat the water once a week with the heating element?
T
toxicmolotof
24 Dec 2017 10:12
The question is whether it is really necessary. German regulations are usually very strict, but in this case, they are surprisingly relaxed.

With 200 liters (53 gallons) in the system, heating from 50 to 70°C (122 to 158°F) uses about 5 kWh. That costs around 60 euros per year. Many people spend that amount on changing their car insurance.

I just wonder if it is truly necessary. We usually manage to empty our storage tank regularly. And nothing stops you from doing it once after a vacation.
tomtom7924 Dec 2017 11:32
I run it up to 45 degrees Celsius (113°F)! And the circulation does the rest.
J
Joedreck
24 Dec 2017 11:37
If you are very concerned about this, you can also install a 300-liter (79-gallon) tank with a fresh water station. However, it does cost a bit more.
I had a fresh water station in my old house and have to say it is excellent.
With the correct sizing of the tank, though, it is equally unnecessary.

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