ᐅ Domestic hot water production according to DIN 1988-200 / Below 60 degrees Celsius in large-scale systems?

Good day.
The drinking water regulation Din 1988 200 states that systems with 2 or more units must operate with hot water at 60°C (140°F), even for modern instantaneous water heaters.

However, clause 9.7.2.3 supposedly allows an exception for larger systems that want to operate below 60°C (140°F) hot water temperatures (for example, hot water at 55°C (131°F), circulation at 50°C (122°F), multi-family house with 5 residential units).

Central drinking water heaters with high water turnover:

If during operation a
water turnover in the hot drinking water installation is ensured
within 3 days,
operating temperatures
can be set to 50°C (122°F). Operating temperatures below 50°C (122°F) should be avoided. The operator must be informed about the possible health risk (legionella growth) during commissioning and instruction.

Does this mean that a large system (e.g., 5 residential units) may operate with a setpoint of around 55°C (131°F) hot water, provided that hot water turnover within 3 days is ensured?
Is it sufficient here if all residents confirm this among themselves?

From an energy-saving perspective, producing hot water below 60°C (140°F) makes sense.
(PS: Legionella are supposedly indifferent to whether the hot water is produced at 55°C (131°F) or 60°C (140°F). This temperature range prevents their spread but does not completely eliminate them. Also, the risk of legionella contamination is lower with instantaneous water heaters, as long as a sufficient turnover of hot water is ensured.)

Are there any practical experiences with this?

Thank you very much!

Operation of hot water storage tanks between 45 and 50 degrees Celsius (113 and 122 degrees Fahrenheit) is common practice. This applies to domestic hot water tanks, hygienic storage tanks, or fresh water stations.

nordanney schrieb:

Operating a domestic hot water storage tank between 45 and 50 degrees Celsius (113 and 122 degrees Fahrenheit) is common practice. This applies whether it’s a potable water tank, hygiene tank, or fresh water station.

However, the Drinking Water Regulation DIN 1988 part 200 states otherwise! Small systems (such as single-family homes) can operate below 60 degrees Celsius (140 degrees Fahrenheit). But larger systems (from 2 units upward) must comply with this regulation, meaning the water must be heated to 60 degrees Celsius (140 degrees Fahrenheit). There is reportedly a gray area where, under certain conditions, larger systems (with circulation and over 3 liters) can produce water below 60 degrees Celsius. While operating below 60 degrees Celsius might be common practice in single-family homes, it is not applicable for multi-family buildings.

Hello.
Why do people get banned?
I haven’t posted any advertisements or anything else!

Hausi99 schrieb:

I didn’t post any advertisements or anything else!

Was there a link included? That alone is enough.

Sorry, in my response I only referred to single-family houses.

Hausi99 schrieb:

However, clause 9.7.2.3 apparently offers an exception for larger systems that want to operate domestic hot water below 60°C (example: hot water at 55°C (131°F), circulation at 50°C (122°F), multi-family house with 5 units).

Central domestic hot water heaters with high water exchange:

If during operation a
water exchange in the domestic hot water system is ensured within 3 days,
operating temperatures can be set to 50 °C (122°F). Operating temperatures below 50 °C (122°F) should be avoided. The operator must be informed during commissioning and handover about the potential health risk (Legionella growth).

Yep. That’s basically it. What is your plan or why do you ask?

I have only set DIN 1988 200. No link or anything else.

Yes, I mean my multi-family house with 5 units! Here, like you probably do, I want to produce hot water at less than 60 degrees Celsius (140°F), because it saves energy (buffer tank) and reduces scaling.

My plan is, if allowed under certain conditions, to produce my hot water at 55 degrees Celsius (131°F) instead of 60 degrees Celsius (140°F). This would mean a lower buffer temperature, less scaling on the heat exchanger, still sufficient hot water, and no increased risk of Legionella.