The indoor unit: where comfort is delivered
The indoor unit contains a heat-exchange coil, a quiet fan, filters and the controls. Wall-mounted units are the most common, but floor consoles suit low walls and conservatories, ceiling cassettes suit suspended ceilings, and ducted units hide above a ceiling with only grilles on show. Size is chosen in kilowatts to match the room’s heat gains, not just its floor area.
Why sizing matters
An oversized unit cycles on and off, wastes energy and leaves rooms clammy; an undersized one runs flat out on hot afternoons and still struggles. Glazing, orientation, occupancy and equipment all feed into the calculation.
Noise you can expect
Modern wall units are designed to run very quietly on low fan speeds, which is why they work in bedrooms. Manufacturers publish sound pressure levels in dB(A) so you can compare models.













