Questioning the 60 degrees. It’s simply expensive and doesn’t bring anything.
We have a brine-water heat pump with probe drilling. Heating up using the probe was rejected by the drilling expert, you don’t do that because of the warranty. Would have liked to use the probe and heating rod simultaneously to go with ~12kW.
Heating up the 2-degree cold and damp shell alone with a 6kW heating rod in January simply didn’t work sufficiently, so an electric heater was used, which was connected to the underfloor heating. It had about 20kW or so. It worked well but costs money for the device, installation, and the electrician also needed some cash on hand for the (temporary) CEE32 indoors. Dumb, but what can you do.