Aircon Cold Draft: When the Air Lands in the Wrong Place

Raising the setting warms the whole room. It does nothing about the air arriving on the person who complained, because that air still leaves the unit on the same line. The complaint survives the adjustment, and now three other people are too warm.

The remote reaches two of the three things that matter: how cold the air is, and on most units how fast it leaves. Where it goes afterwards is geometry, settled by the height of the unit, the wall it sits on and where the furniture ended up.

This is why one flat can hold two honest opinions about the same room. The person in the path wants the number higher; everyone outside it is settled, and the setting drifts upward over an evening with nobody arriving anywhere good.

A free test separates the two cases. Ask whether the complaint travels with the person or stays with the seat. Somebody who moves to the other end of the sofa and stops minding has described a delivery problem; somebody who takes it with them has described something broader.

The comfort standards keep these on separate books, and the separation is the useful part. One assessment asks whether the room as a whole suits the person in it; a second asks whether one part of one person is treated differently from the rest. ASHRAE 55 and ISO 7730 both file draught under the second heading.

The definition is narrower than the everyday use of the word. Draught, in those standards, is unwanted local cooling of the body caused by air movement. Air movement alone is no fault and is the entire reason a fan earns its keep; what makes it a draft is that the person did not ask for it and cannot walk away.

The head and neck deliver the verdict for the whole body. The model the standards rely on was developed to predict draught at the neck and found the head the most sensitive region for people in ordinary indoor clothing. That explains why a bed is the worst arrangement in any flat: everything below the shoulders is under a blanket, and the exposed part is the one most likely to object.

The model also counts how much air speed fluctuates, not only its average, and swing mode converts constant exposure into repeated exposure. Neither version removes the stream from the room.

One more condition in the model matters more than it looks: it describes a person sitting still, at rest or close to it. That is the bed, the desk and the sofa, not somebody walking through the living room. A person crossing the path leaves it within seconds; a person at the same desk all afternoon has been inside it the whole time, which is why the complaint attaches to fixed positions.

The wall unit above the bedroom door produces most of these calls. Bedrooms here are narrow, and the tidy position is high on the wall near the door, where the pipe run to the ledge is shortest and a hole may already exist. The bed goes against the opposite wall because that is where it fits, so the unit is aimed down the room at the headboard.

A small room gives the air nowhere to lose itself. Air leaving the coil is colder and denser than the room, so it sinks as it slows. A large room offers distance to mix and arrive diluted; a short bedroom does not, and the pillow sits inside what is still recognisably a stream. Extra capacity makes this worse, since a larger unit pushes more air through the same room.

Ceiling cassettes discharge on several sides at once, so at least one side finds a person. A cassette above a dining table or workstation has no neutral aim available; vanes narrow the angle, but the air descends from overhead onto the part of the body that reports first. A wall unit at least starts its air off horizontally.

In living rooms the fault is usually furniture. A sofa gets placed to face the television, the aircon was placed to suit the pipework, and the two decisions were made months apart by people who never spoke. One end of that sofa sits in the path and the other does not; most households quietly stop using the bad seat.

Two of the three variables are still open after installation. Air temperature and fan speed remain adjustable, and the aim can be nudged. The unit's position is settled, and reopening it means pipework.

The louvre is the first thing to try and the most oversold. Lifting the horizontal vanes sends air along the ceiling rather than out into the room, delaying its descent and buying distance. It does not delete the descent: that air still comes down, and a short bedroom runs out of ceiling. Some units also revert to a default aim when power is cut.

Fan speed trades one half of the sensation for the other, and households usually guess the direction wrong. At a given cooling output, slowing the fan means the same heat is carried by less air, so what leaves the unit is colder but slower. Speeding it up gives faster, less cold air. Both remain a stream landing on the same person, so calling either a fix oversells it.

Furniture is the change most households refuse and the one that works. Shifting a bed off the axis of the unit, or turning a desk to face another way, removes the person from the path and costs nothing. It is unpopular because layouts were decided for other reasons, but it remains the only free answer.

Clip-on deflectors are a partial answer with a known side effect. A baffle across the outlet spreads air sideways or upward, and whether one fits depends on the shape of the unit's face. The risk is short-circuiting: a deflector pushing discharged air back toward the intake feeds the unit its own cold output, so cooling backs off and the room never quite arrives.

Relocation is the honest answer where the geometry is genuinely wrong, and it is not a small job. Moving a unit means a fresh core hole, a new pipe route, a drain gradient that keeps falling the whole way, and making good the wall left behind. A draft complaint is an expensive reason to meet those costs.

The quoting visit is the cheap moment to decide where the air goes, and there is not a second one. An installer measuring a room is already choosing a position using legitimate criteria: pipe length, the route to the ledge, the fall for the drain, and whether a hole already exists. Not one is about people.

Say where people sit and sleep before anything is marked on the wall. The headboard, the desk, the end of the sofa somebody actually uses. An installer handed that information will usually work around it, because the alternative positions were sitting there the whole time with no reason to be preferred over the convenient one.

Then ask a single question, which settles most of it: from the position being proposed, where does the air land. Anyone competent answers immediately, because it is the same judgement they used to place the unit. An answer that redirects to capacity or brand is worth noticing.

Expect a trade and settle it in the same visit. A better position is often a longer pipe run, a second core hole, or trunking across a wall somebody wanted left clean. Those are genuine costs and belong in the conversation before the drill comes out, not afterwards when the bedroom is uncomfortable.

Replacements inherit the geometry unless somebody objects. Swapping a unit into the existing position keeps the existing aim, including a draft the household has quietly tolerated for years. Raise it then, since the wall is open and the pipework is handled anyway. Like for like is a decision about geometry, worth making on purpose.