Load ratings and pipe sizes
Many parts here are made for particular brands or models, so check what a part fits before anything else. Outdoor unit brackets are rated by the weight they carry, at 60, 90 or 140 kilograms, and the rating should comfortably exceed the weight of the unit. Refrigerant pipe pairs a 1/4 or 3/8 inch liquid line with a 3/8, 1/2 or 5/8 inch gas line, and both must match the connections on the system, with larger systems using larger pipe.
What each kind of system needs
A portable unit needs a window seal kit to close the gap around its hose, and an extension kit made for that model if the hose will not reach, because a longer run makes it work harder. A split system needs pipe, a bracket for the outdoor unit and, wherever the water cannot drain away downhill, a condensate pump. Controls change how you run it: a wireless remote, a wired controller fixed to the wall, or a controller that works from a phone app.
Who fits what and what to clean
Seal kits, hose extensions and remotes need no tradesperson, but refrigerant pipe must be connected by an F-Gas registered installer, and brackets need fixings rated for the load in sound masonry. A condensate pump needs a power supply, a job for a qualified electrician if it is wired in, and its reservoir and filter need cleaning so it does not block and overflow. Window seals wear with use, so replace one once it no longer closes the gap.
