Heat Pump at 1,545 Meters: Heating System Replacement at the Raxalm.

The Rax Cable Car has been operating up to the Raxalpe since 1926; in 2026, it will celebrate its 100th anniversary. At 1,545 meters above sea level, right next to the mountain station, lies Scharfegger’s Raxalm Mountain Inn with its panoramic terrace. The building was heated by two old oil-fired boilers.

Bernd Scharfegger, owner of the Rax Cable Car and Scharfegger’s Raxalm, reached out to Harald Grabner, CEO of Heizbär. The goal: a new heating solution. Planning began in collaboration with OVUM.

“[…] it was very clear to us that we […] also wanted to operate more efficiently in order to reduce costs. If we also wanted to think about the future, it was necessary to find a sensible, long-term solution.”

Bernd Scharfegger, owner of the Rax Cable Car and Scharfegger’s Raxalm

 

According to Bernd Scharfegger, there were no precedents of this kind for a project of this nature during the planning phase. Consequently, there were many initial questions: How will the plant perform in sub-zero temperatures, and how will it even work on a mountain?

“These concerns were dispelled relatively quickly by our experts and, above all, by the staff at Heizbär, who actually came up with very sound calculations quite quickly.”

Bernd Scharfegger

Added to this was the existing infrastructure. According to Harald Grabner, the biggest challenge lies in the interaction of over 100-year-old heating technology—including gravity-fed piping and cast-iron radiators—the long transport routes, and the integration of numerous electronic components. Furthermore, the inn’s operations could never be shut down. Heizbär therefore replaced and installed the heating system while the inn remained open for business, a task that Grabner describes as very demanding.

A bivalent plant was planned, meaning two heat generators working in tandem. Two OVUM AC520P air-source heat pumps cover the majority of the heating demand and can be controlled alternately. The old oil-fired boilers were replaced during the renovation. For very low outdoor temperatures, an oil-fired system remains part of the system as a secondary heat generator.

To make room for the equipment, some renovations were necessary: The former ice storage room of the mountain inn is now the boiler room. It houses the Heat Pumps’ buffer tanks, the system separator, and the charging pump that supplies the entire building. A hygienic hot-water system based on the fresh-water principle was also newly installed.

Controller: output-based rather than constant flow temperature

A unique feature is the Controller. The building is not controlled via constant flow temperatures, but rather on a power-based system. This is ensured by a freely programmable MSR control system: It receives data from all consumers and issues the commands required by the system.

Data provided by the operator after one year of operation, rounded. This is a specific case: The performance of a Heat Pump in another building depends, among other things, on the building, heating load, location, and usage, and is determined on a case-by-case basis.

From the perspective of those involved, the project demonstrates that Heat Pumps are not only suitable for modern single-family homes with underfloor heating but can also be integrated into existing buildings with radiators. According to Bernd Scharfegger, anyone interested in seeing the Plant in person is warmly invited to visit Raxalpe.