ᐅ Air conditioning system for single-family home upper floor, split-type air conditioner

Hello,

I’m new here :o ... a warm hello to everyone.

Scenario: Single-family house, old building, about 50cm (20 inches) brick walls, with 5cm (2 inches) external thermal insulation. During the recent heatwave, the upper floor reached about 29°C (84°F) – making sleep impossible. Idea: Air conditioning, at least for the upper floor.

Since it’s not possible for me to retrofit condensate drain hoses in the rooms (so individual or multiple room units are out of the question), I came up with the following idea:

• a slightly larger split system installed only in the central staircase area on the upper floor,
• cooling pipes running up and across the attic to the outdoor unit,
• the (one) condensate drain hose could somehow be routed outside.

Questions: Does this make sense (of course, the doors to the rooms would need to stay open)? How much cooling capacity in kW would I need (the entire upper floor is about 100m² (1076 ft²)), although I definitely wouldn’t want to cool everything down to 20°C (68°F). Also, how noisy is the outdoor unit – is the humming significantly disturbing?

Thanks for any advice.

Best regards