How to vent a portable AC through a balcony or French door

Balcony and French doors are common in EU flats, and they are tall enough that a normal window kit cannot span them. Many also have tilt-and-turn hardware on one leaf. The gap is the issue: a standard kit reaches about 400 cm of perimeter, and a floor-to-ceiling door needs more.

Use a door-sized seal

The Trotec AirLock 1000 is built for this: a cloth seal with a 560 cm perimeter, made for balcony and patio doors and floor-to-ceiling tilt-and-turn glazing. It has two adjustable zips, so it handles a single or dual-hose unit, and it fits between the door and the frame so you can close the door onto it.

Fit it with the door open, run the hose through one zip, close the unused zip airtight, and bring the door to rest against the cloth. For a very tall opening, some people combine a rigid lower panel carrying the hose hole with cloth above it.

The security advantage

A balcony door propped open on a hose is an obvious entry point on a ground or first floor. The reason a cloth seal beats propping is that the door can still close and lock against it when you leave. That is the safer setup, and it is worth choosing over a wedge or a gap.

A mobile split is cleaner still: its thin line slips under the nearly-closed leaf, and the door locks behind it. If your balcony can take the outdoor module, it is the tidiest answer for a door.

Rain at the threshold

Keep the cloth taut so rain at the threshold sheds outward rather than running in, and slope the hose down to the outside. A door threshold sees more driven rain than a first-floor window, so a snug seal matters.

Single hose, dual hose or split

The AirLock 1000’s two zips cover single and dual-hose units; seal the spare zip. A mobile split needs no exhaust seal at all. Which to buy comes down to the room and whether the balcony can hold an outdoor unit.

Run the finder and pick “balcony / French door” for the window; it will match a unit and the right seal.