Experiences with split air conditioners in old buildings – what to consider?

Hello everyone,
we live in an older building (built in 1960, insulation average) and are considering whether the installation of a split air conditioner is worthwhile – especially for the hot summer days.
It is important to us to have a quiet indoor and outdoor unit, good efficiency (preferably A++ or better) and of course a solution that does not cause a complete construction site.
We have already had a preliminary conversation with a local provider who recommended the Mitsubishi Electric MSZ-HR35VF – does anyone know this model?
Are there people here with experience in retrofitting in existing buildings? What should definitely be considered (e.g. condensate, wall penetrations, noise for neighbors, etc.)?
Looking forward to any tips – also gladly with pictures or concrete recommendations.
Best regards

If you want to retrofit in an old building, the MSZ-HR35VF is actually okay in terms of efficiency and noise – it is quite quiet and A++ is acceptable. When installing, you should carefully plan the routing for power, refrigerant, and condensate with the specialist company, otherwise there will be unpleasant surprises when breaking through the walls. Especially the condensate must be safely drained outside, otherwise moisture problems will quickly arise. Outdoor area: sound isolation of the outdoor unit is mandatory so that the neighbors are not annoyed by vibrations or humming. The shorter the distances between the indoor and outdoor units, the more efficient and trouble-free it operates. Proper installation is essential; it’s better not to save money on the cheapest provider. By the way: in some regions, installation requires a permit, so check the [Landesbauordnung] beforehand.