How noisy is a wall-mounted air conditioner?

Noise is one of the first things people ask about before fitting air conditioning in a bedroom or a living room. The figures below come from the Samsung WindFree Comfort UK product data sheet (opens in a new tab), the system on our Bronze package, so you can see real numbers rather than a marketing line. For our other five packages, we can go through each manufacturer's figures with you at your free survey.

Manufacturers publish two different noise figures, and it helps to know which is which. Sound pressure is closer to what you would actually measure standing a set distance from the unit, and it is usually given for the quietest (silent or low fan) setting and the highest fan speed. Sound power is a single figure for the unit itself, independent of distance, and some data sheets give only this figure rather than a separate silent-mode pressure rating.

The outdoor unit is usually what a neighbour would notice, not the indoor one, which is why its position matters as much as the figure on the data sheet.

The number on a data sheet is measured under test conditions, so a few real-world things change how noticeable a system feels in your home:

• Distance and position. A unit mounted higher on a wall, further from where you sit or sleep, feels quieter even at the same rated noise level.
• Hard surfaces nearby. A patio or a close fence panel can reflect outdoor unit noise back towards a window, making it feel louder than the figure alone suggests.
• Fan speed. Every system we fit runs at a lower fan speed once the room reaches the set temperature, which is quieter than the figures for the highest setting shown above.
• Open windows. An open window near the outdoor unit lets more of its noise into the room than a closed one, which matters most overnight.

If low noise indoors matters more than anything else, the Samsung WindFree Comfort's published silent-mode figure of 16 dB(A) at 3.5kW is very low, and its WindFree mode avoids a direct draught too. For the other packages, ask us for the manufacturer's figures and we will compare them with you for your room.

The figures above are all for the 3.5kW size. On Samsung's own UK data sheet, the WindFree Comfort outdoor unit gets slightly louder as the size increases, which is worth knowing if you are deciding between two sizes for a room on the edge of a size bracket.

The difference between 2.5kW and 5kW is a few decibels, which is one more reason to choose the size that actually suits the room rather than sizing up "to be safe." Our sizing guide covers how we work out the right size at survey.

Beyond the unit itself, how it is fitted affects how noticeable it is day to day. We mount outdoor units on proper anti-vibration feet rather than resting them directly on a hard surface, keep pipe runs supported so they do not rattle against a wall, and talk through outdoor unit position with you at survey, balancing easy access for servicing against distance from a bedroom window or a neighbour's garden.

For more on how the Samsung WindFree Comfort compares with Mitsubishi Electric, see our Samsung WindFree vs Mitsubishi Electric guide, and check current prices for your room size to compare all six packages.

A correctly sized air conditioning installation also helps with noise, because an oversized unit for the room often cycles on and off more, which is more noticeable than a correctly sized system running steadily at a lower speed. Our bedroom air conditioning guide covers placement and sizing specifically for overnight use.