Capacity, inverter or not, and whether parts exist in this country. The brand matters least of the three.
People ask us which brand to buy and we usually end up talking about three other things first, because the brand is genuinely the least important of the four.
Capacity. Work it out rather than rounding up. In Malé, with concrete walls that hold the day's heat, about nine thousand units of capacity for a small bedroom, twelve for an ordinary one, eighteen for a living room with a west facing window, and more if the room has a lot of glass, a lot of people or a lot of equipment. Undersized is obvious: the unit runs all day and never gets there. Oversized is less obvious and worse to live with. It cools the air quickly, switches off, and never runs long enough to pull the humidity out, so the room is cold and damp and everybody feels sticky at twenty three degrees. That is the single most common complaint we are called out to on a unit that has nothing wrong with it.
Inverter or not. An inverter unit varies its compressor speed instead of switching on and off, which means it uses roughly a third less electricity and holds a steadier temperature. It costs more to buy. For a room used more than about four hours a day it pays that back inside two years, and for a bedroom used every night it is not a close call. For a spare room used twice a month, a non inverter unit is the sensible purchase and we will say so.
Parts. This is the question nobody asks and it is the one that decides whether a five year old unit is repaired or thrown away. There are brands sold in this country whose fan motors and control boards cannot be bought here at any price, and when one fails the whole machine is scrap. Ask whoever is servicing your units which brands they can get parts for from their own experience, not from a brochure. We will answer that on the telephone for nothing.
Then placement, which is half the life of the machine. The outdoor unit wants free air on three sides, a position above the height people walk past, shade from the afternoon sun if there is any to be had, and distance from a bedroom window, because the air off it is about forty degrees and the fan is not silent. Keep the pipe run short: over about fifteen metres it needs larger pipe and extra gas, and the efficiency falls whatever you do. And if the only wall available faces the sea, accept it and plan to wash the coil four times a year instead of twice.
Last, the boring one. Ask for a drawing of where the pipes run and where the isolator is. We hand one over on every installation, and the reason is that three of the fit outs we have inherited had none, and finding a buried refrigerant pipe with a drill is how a ceiling gets opened twice.