Indoor airflow comes first
The indoor unit needs space to draw in and distribute air. Avoid positions that create a constant draught onto a bed, desk or sofa, and do not obstruct the manufacturer clearances with tall furniture or curtains.
A central-looking position is not automatically best. Room shape, open doorways, high ceilings, glazing and where people spend time all affect how conditioned air moves.
Routes and drainage must work
Refrigerant pipework, communication cable and condensate drainage connect the indoor and outdoor equipment. A neat, serviceable route should be identified before drilling begins. Gravity drainage is often preferable where practical, while pumps introduce additional equipment and maintenance considerations.
The wall construction and route through the property can affect disruption and the visible finish. These details should be shown or explained in the quotation.
Outdoor units need breathing and access space
The outdoor unit must have manufacturer clearances for airflow and should be reachable for future servicing. Enclosed corners, weak structures and positions that direct sound toward neighbours may be unsuitable.
Appearance, planning or leasehold conditions, drainage and vibration control can also influence the location. The quietest result depends on both equipment sound data and competent positioning.