Can I install an outdoor unit of 18.000 or 24.000 Btu/h on the wall in order to save space in my balcony?

Air conditioners of 18.000 or 24.000 Btu/h are high performance – heavier units regarding to the external unit. This results in larger vibrations during the operation and therefor more noise. If you install the above outdoor units on the wall you may cause noises as well as vibrations, all this depending on the wall characteristics (single walls, old buildings etc.) You can avoid this by installing the outdoor unit on the ground as regulated by the law.