In the Advent season, the Tölzer Kurier takes a look behind a door in the district that is normally closed to the public in every issue.
Today: The ice heating in Tölz town hall.
Bad Tölz
- When structural engineer Stefan Öttl leads groups of visitors into the basement of the town hall at the open house, he knows one thing for sure: he looks into many perplexed faces.
The ice heater is located in the basement - sounds strange, works strange and is largely unknown in private homes.
Birte Otterbach no longer wants to do without the somewhat bizarre heating system.
"The climate in the town hall is extremely pleasant all year round," says the press spokeswoman for the city of Bad Tölz.
The difference to air conditioning is striking: "With our ice heater, I never have the feeling that I have to put on a scarf because it is pulling."
The idea of installing an ice heater in the town hall came about as part of an ideas competition.
Four planners should come up with suggestions on how best to heat the town hall.
There were traditional suggestions like wood chips and pellets - and an ice heater.
That made the then mayor Josef Janker curious, says Otterbach, "because he is incredibly adept at building and has a great interest in technical systems like this." Apart from the fact that the heating is ecologically interesting as it does without fossil fuels.
When water freezes, heat is obtained
In order to fully understand how an ice heater works, you need a degree in physics.
Even the simplest attempts to explain it sound like a secret code.
It's hard to imagine that freezing water can produce enough heat to heat an entire house.
But it works.
Because during icing - from the point in time when the first ice crystals form to complete solidification - water gives off a lot of energy.
To be more precise, about 80 times more than simply cooling it down by one degree Celsius.
This energy is called solidification or crystallization heat and makes it possible to use ice storage also in heating.
The ice store is located on the back of the building between the entrance door and the Bürgergarten - it is an underground tank with a concrete wall that has space for 220 cubic meters of water.
+
An inconspicuous door leads to the ice heating system in Tölz town hall.
© Arndt Pröhl
“During the heating season, the water in the ice store gets colder because the energy for heating is withdrawn,” explains Öttl.
“And in summer it's the other way around.
The ice melts and the cold water is pumped through the house. ”In order for this to work, all kinds of technical equipment are necessary, for example a heat pump.
Öttl: "Basically you have to imagine the system like a refrigerator that runs backwards."
Ice heating is also conceivable in private houses
The calculation is extremely difficult: “A specialist engineer has to say: We need so and so much energy in this building.
We needed two heating periods for the exact calibration. ”However, the heating always worked in this phase, emphasizes Otterbach:“ As laypeople, we didn't notice anything.
The only thing we saw: that Stefan is walking hectically through the house again. "
In principle, such a type of heating is also conceivable in private houses, but many people shy away from the acquisition costs and the "fine tuning" that is necessary after installation: "But we have a casual bunch here when it comes to building construction," says Öttl.
"Everyone says: If there is something that is efficient, then we'll do it. Together, we always get everything working." And no matter how complicated it is, heating systems.
In the Advent door series, the Tölzer Kurier also looked into the bell tower of the basilica in Benediktbeuern and the railway depot in Lenggries.
