Air conditioning for bedrooms

Noise is the thing to get right

In every other room, noise is a minor consideration. In a bedroom it decides whether you actually use the system or switch it off after a week.

Manufacturers publish sound pressure levels for their indoor units, usually at several fan speeds. The figure that matters to you is the one at the lowest fan speed, because that is where a bedroom unit spends most of the night. Ask the installer for that specific figure for the specific model they are quoting — not the range for the brand.

Two other things affect what you actually hear. A unit sized correctly for the room reaches temperature and settles into low fan speed, whereas an undersized one runs hard for longer. And an outdoor unit mounted directly outside a bedroom window will be audible through it, so its position is part of the bedroom conversation too, not just the indoor unit’s.

Where the indoor unit should go

The general rule is that you want the air circulating through the room rather than blowing across the bed. A unit mounted on the wall above the head of the bed, or on the opposite wall directing airflow over it rather than at it, usually works better than one aimed squarely at where you sleep.

Practical constraints normally narrow it down quickly:

• It needs a wall with an outside face, or a viable route to one for the pipework and condensate
• It should not be blocked by a wardrobe, a curtain rail or a sloping ceiling
• It needs clearance around it for airflow and for the filters to be cleaned
• It should be somewhere you can actually reach to maintain

In loft conversions and rooms with sloping ceilings the options narrow further, and it is worth mentioning that on the enquiry so the installer arrives expecting it.

Sizing a bedroom properly

Bedrooms are usually smaller than the other rooms people cool, so it is tempting to assume the smallest unit in the range will do. Often it will. But the heat load depends on more than floor area.

The things that push a bedroom’s requirement up are large or south-facing windows, a room above a garage or conservatory, a loft conversion under a warm roof, poor shading, and the simple fact of two people sleeping in it. A small room that bakes all afternoon can need more capacity than a larger, shaded one.

Oversizing has its own downside: a unit with far more capacity than the room needs cools quickly and then cycles, which is generally noisier and less comfortable than a correctly sized unit running steadily at low fan. Getting this right is the main thing the survey is for.

Night-time running and controls

Most domestic systems have some form of night or sleep mode, which typically restricts fan speed and gradually shifts the target temperature through the night. Ask what the specific system does, because the behaviour varies between manufacturers.

Worth asking about at the same time: whether the display can be dimmed or turned off, whether there is a timer to have the room cool before bed rather than running all night, and whether the controls are app-based, remote, or both. In a bedroom, a bright status LED is a genuine annoyance.

Will it heat the room in winter?

Most modern domestic split systems are air-to-air heat pumps, so the same unit can heat as well as cool. In a bedroom that can be useful in shoulder seasons, though heating performance varies by system and by outdoor temperature.

If winter use matters to you, raise it at the quote stage and ask the installer to confirm what the specific system will do rather than assuming a category. It can influence which model is right.