ᐅ Multi-day Power Outage as Currently Experienced in Berlin: Risks for Heating Systems and Water Pipes?
Created on: 6 Jan 2026 10:01
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Pianist
Good day!
As you probably know from the news, there is currently an extended power outage in the southern part of Berlin, which started on Saturday and is expected to last until Thursday. This makes me wonder: what impact does a multi-day power outage have on building systems when outside temperatures are below freezing?
Let’s assume that a house in an unprepared state would no longer be habitable by usual standards. The fresh water system can be drained, and the local water supplier can be asked to shut off the supply line in the street. This should take care of that aspect. But what about the circulation water in the heating system? It’s unlikely that every radiator or underfloor heating loop can be completely drained reliably.
How long does it take for a well-insulated house, constructed with materials that have good thermal mass, to freeze enough that there is a risk of heating pipes bursting? The consequences would be severe, potentially requiring the removal of the screed…
So, let’s assume minus ten degrees Celsius (14°F) and a week without power. Are there any experience reports from previous events?
Matthias
As you probably know from the news, there is currently an extended power outage in the southern part of Berlin, which started on Saturday and is expected to last until Thursday. This makes me wonder: what impact does a multi-day power outage have on building systems when outside temperatures are below freezing?
Let’s assume that a house in an unprepared state would no longer be habitable by usual standards. The fresh water system can be drained, and the local water supplier can be asked to shut off the supply line in the street. This should take care of that aspect. But what about the circulation water in the heating system? It’s unlikely that every radiator or underfloor heating loop can be completely drained reliably.
How long does it take for a well-insulated house, constructed with materials that have good thermal mass, to freeze enough that there is a risk of heating pipes bursting? The consequences would be severe, potentially requiring the removal of the screed…
So, let’s assume minus ten degrees Celsius (14°F) and a week without power. Are there any experience reports from previous events?
Matthias
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MachsSelbst13 Jan 2026 14:40I was actually quite surprised that air-to-water heat pumps are often designed so sensitively that they cannot survive 2 or 3 days without power in freezing temperatures without ending up completely damaged.
I can fully understand why these people are upset. They invested a lot of money jumping on the "everything powered by electricity" trend, and now the outdoor unit is broken, leading to high repair costs and, above all, waiting times... maybe my gas heating system wasn’t such a bad choice after all...
I can fully understand why these people are upset. They invested a lot of money jumping on the "everything powered by electricity" trend, and now the outdoor unit is broken, leading to high repair costs and, above all, waiting times... maybe my gas heating system wasn’t such a bad choice after all...
Nida35a schrieb:
When I read this, I hope the damaged heat pump had a maintenance contract with annual servicing; otherwise, the insurance company might have a reason not to cover the damage.I doubt that, since heat pumps generally require little maintenance, and depending on the model, they can even be maintenance-free.N
nordanney13 Jan 2026 18:11MachsSelbst schrieb:
I was actually quite surprised that air-to-water heat pumps seem to be designed so sensitively that they can’t withstand 2 or 3 days of freezing temperatures without power without ending up completely damaged... They don’t. The problem “only” occurs if water in the pipes freezes. Otherwise, practically nothing happens. By the way, I “tested” this before installing two heat pumps. After purchase, they were left outside during the winter and were not connected. One was even left like that for almost 1.5 years...
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MachsSelbst13 Jan 2026 18:26This is once again a very theoretical approach, following the idea "If you don’t fly, you can’t crash..."
Yes, water is the issue, but many monoblock units have the water circuit routed outside, and the recommended insulation thickness is often not maintained. This is what you call practical experience, and this reality likely caused many heat pumps to fail during the cold power outages at night in Berlin...
Routing the water circuit to the outdoor unit is a design weakness... so such heat pumps are inherently vulnerable by design... period. Thank you.
Yes, water is the issue, but many monoblock units have the water circuit routed outside, and the recommended insulation thickness is often not maintained. This is what you call practical experience, and this reality likely caused many heat pumps to fail during the cold power outages at night in Berlin...
Routing the water circuit to the outdoor unit is a design weakness... so such heat pumps are inherently vulnerable by design... period. Thank you.
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nordanney13 Jan 2026 19:12MachsSelbst schrieb:
This is what you call practical experience, and many heat pumps will have failed during the cold, power-outage nights in Berlin... And this brings us back to the start of the thread. Drain the water and calmly face the blackout.
MachsSelbst schrieb:
So these heat pumps are sensitive by design... period. Thanks. But you do realize that every year around 10,000 insurance claims are reported due to frost damage (plus those who chose not to have insurance)—frozen pipes and the like. So here’s a bold statement: the entire water supply and drainage systems in Germany have been designed too sensitively for many decades. Yours too. You probably have “bad materials” in your house as well. Period. Thanks 😎 😀
In the end, it’s physics. Expanding water is hard to control. You simply cannot build "that robust."
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