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 is still leaving the unit on the same line it always did. The complaint survives the adjustment, and now three other people are too warm as well.

The remote reaches two of the three things that matter. How cold the air is, and on most units how fast it leaves, are both under its control. Where it goes afterwards is geometry: the height of the unit, the wall it sits on, and where the furniture ended up. None of those are on the remote.

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 the path is already settled and gets overruled anyway. The setting drifts upward over an evening and nobody arrives anywhere good.

There is a test that costs nothing and 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. Perceived temperature is a subject in itself, and another guide already carries it.

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 being treated differently from the rest of them. ASHRAE 55 and ISO 7730 both file draught under the second heading, in company with a cold floor and a wall radiating heat at you.

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. Two of those words carry the weight. Air movement by itself is no fault at all, and is the entire reason a fan earns its keep. What turns it into a draft is that the person did not ask for it and cannot walk away from it.

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 it found the head region to be the most sensitive part of the body for people in ordinary indoor clothing. That single fact explains why a bed is the worst arrangement in any flat. Everything below the shoulders is under a blanket, and the one part left exposed is the part most likely to object. Where the sleeper is an older person, aircon for the elderly is handled in its own guide.

That model also counts how much the air speed fluctuates, not only its average. A steady stream and a gusty one at the same average speed do not land the same way. Swing mode sits directly on that point: it converts constant exposure into repeated exposure, which some people find easier and others find worse. 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, and it is nobody walking through the living room on the way to the kitchen. A person crossing the path leaves it within seconds. A person working at the same desk all afternoon has been inside it the whole time, which is why the complaint always attaches to the fixed positions.

The wall unit above the bedroom door produces most of these calls. Bedrooms here are narrow, and the tidy place for an indoor unit is high on the wall near the door, where the pipe run to the ledge is shortest and a hole often exists already. The bed then goes against the opposite wall or under the window, because those are the only places it fits. The unit is now aimed down the length of the room at the headboard.

A small room gives the air nowhere to lose itself on the way. Air leaving the coil is colder and denser than the room it enters, so it sinks as it slows down. A large room offers distance for that air 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 rather than better, since a larger unit pushes more air through the same small room, and the oversizing guide covers what else that buys.

Ceiling cassettes discharge on several sides at once, so at least one side finds a person. A cassette above a dining table or a workstation has no neutral aim available to it. Vanes narrow the angle, but the air is descending from directly overhead onto the part of the body that reports first. A wall unit at least starts its air off horizontally. What sits above the grille belongs to the ceiling cassette guide, and the geometry below it belongs here.

In living rooms the fault is usually furniture rather than the unit. A sofa gets placed to face the television, and 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 work this out on their own and 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 position of the unit is settled, and reopening it means pipework.

The louvre is the first thing to try and the most oversold. Lifting the horizontal vanes sends the air along the ceiling rather than out into the room, which delays its descent and buys some distance. It does not delete it, because that air still comes down, and a short bedroom runs out of ceiling before it finishes falling. Some units also drop the setting when power is cut and go back to a default aim. A louvre not moving at all is a separate fault with a page of its own.

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 being carried by less air, so what leaves the unit is colder but travelling slower. Speeding it up produces faster air that is less cold. Both remain a stream landing on the same person. The trade is real and worth trying, but describing it as 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 the layout was decided for other reasons and everybody has got used to it. It is still the only free answer on the list.

Clip-on deflectors are a partial answer with a known side effect. A baffle across the outlet spreads the air sideways or upward instead of straight out, and whether one fits depends on the shape of the unit's face. The risk is short-circuiting: a deflector that pushes discharged air back toward the intake feeds the unit its own cold output, which then reads as a room that has already arrived at the setting. Cooling backs off and the room never quite gets there.

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 on the wall left behind. Each of those has a guide to itself. A draft complaint is an expensive reason to meet them for the first time.

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 criteria that are entirely legitimate: pipe length, the route out to the ledge, the fall available for the drain, and whether a hole is already there. Not one of those criteria is about people.

Say where people sit and sleep, and say it 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 without argument, because the alternative positions were sitting there the whole time and simply had 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 that immediately, because it is the same judgement they were already using to place the unit. An answer that redirects the conversation to capacity or brand is worth noticing.

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

Replacements inherit the geometry unless somebody objects. Swapping a unit into the existing position keeps the existing aim, including a draft the household has been quietly tolerating for years. That is the moment to raise it, since the wall is open and the pipework is being handled anyway. Like for like is a decision about geometry, and it is worth making on purpose rather than by default.