ᐅ New Heat Pump for an Older Home Without Renovation

No. The decisive factor is always the flow temperature.
Set all thermostatic radiator valves to 5 and lower the flow temperature until the reference room (usually the bathroom, as higher temperatures are desired there) is just comfortably warm.
Check the radiators to see if they warm up evenly. If one or more radiators are warm at the top but cold at the bottom, a hydraulic balancing must be carried out.
The heat output surface area is crucial in order to operate at lower flow temperatures. This means that the larger the radiators, the lower the flow temperature can be.
Replacing the heating system with a heat pump therefore makes sense together with low-temperature radiators.

This description is insufficient. There are heating boilers that, due to control settings, cannot operate below, for example, 50 degrees Celsius (122°F) as the boiler temperature. If no mixing valve is installed, the minimum flow temperature is generally also around 50 degrees Celsius (122°F). This can make things difficult.

That's true, but the regulation does not allow it anyway.
You just get an indication of whether you can or could lower the supply temperature further.

SaniererNRW123 schrieb:

For everyone considering installing a heat pump in an older building.

Panasonic is launching a high-temperature heat pump in spring 2023 that can deliver a flow temperature of 75°C (167°F) even at an outside temperature of -10°C (14°F). It is said to have a maximum SCOP of 5.2. This makes it an alternative to oil and gas heating without the immediate need to switch to underfloor heating and/or additional insulation.

No further details are yet available about the Aquarea L; they will be released later.

A friend works in the industry and traveled extensively internationally over the summer, speaking with professionals in the field. He advised us (in an older building) to wait before switching to a heat pump, as there are expected to be significant developments for older buildings soon. This aligns with your message. I am curious to see what exactly will come to market. Current heat pumps would require extensive renovations here and be very costly, which is why we have moved away from that idea; such an investment probably would never pay off.

I would also wait and see what actions the government will take. Subsidies, possible caps on heat pump tariffs, etc. Then a hybrid system often becomes worthwhile. It’s always a matter of calculation...

Why not simply use air-to-air systems instead of inefficient radiators requiring high flow temperatures?