Where to place the indoor and outdoor unit of your AC

Two decisions made in the first ten minutes of an installation determine whether an air conditioner cools evenly, runs quietly, and costs what you expected: where the indoor unit goes, and where the outdoor unit goes. Both are much cheaper to get right before the drill comes out. Here is what actually governs the choice.

The indoor unit: height, clearance, airflow

A wall-mounted indoor unit throws cool air outward and slightly upward, and lets it fall across the room as it cools. That single fact drives most of the rules.

Mount it high — near the top of the wall with roughly 15 cm of clear space above and free space either side, so it can pull air in at the top and discharge without obstruction. Choose the wall that gives the longest unobstructed throw across the room, so the airflow reaches the far corner instead of hitting a wardrobe two meters away. In an L-shaped or open-plan space, aim along the longest axis; the same logic that governs sizing an open-plan room governs where the unit points.

Where not to put the indoor unit

• Directly above or facing a bed, sofa, or desk. A continuous draught on one person is the most common post-installation complaint, and it makes people set the temperature wrong to compensate.
• Above a heat source — a radiator, a fridge, a TV. The unit reads the room temperature at its own intake, so local heat makes it misjudge the room.
• Behind curtains, inside a cabinet, or tight against a corner. Blocked intake or discharge is a direct efficiency loss.
• On a wall in strong direct sun, especially an uninsulated west-facing one, for the same reason.
• Where you cannot reach the filters. Filters need cleaning monthly in heavy use; a unit over a stairwell makes routine servicing a chore that quietly stops happening.

Drainage decides more than people expect

The indoor unit produces condensate continuously while cooling, and it drains by gravity. The drain line has to run downhill the whole way to its outlet. This is the single most common cause of water dripping from an indoor unit months after installation — a sagging or back-fallen drain line, not a faulty unit.

Practically, that means the chosen wall needs a viable route for the drain to reach outside or into a waste point, always descending. Where the geometry does not allow it, the alternative is a condensate pump: a working solution, but an added component with an added noise and a failure point. A route that drains by gravity is worth some flexibility on the exact mounting spot.

The outdoor unit: air, shade, and access

The outdoor unit dumps the heat, so it needs air more than anything else. Give it clear space in front of the fan discharge and behind the coil, and never fully enclose it — a boxed-in unit re-inhales its own hot exhaust, loses capacity exactly when you need it most, and can shut down on protection in a heatwave. Decorative covers are fine when they are genuinely open.

Beyond airflow:

• Shade helps, enclosure hurts. A shaded north or east wall is ideal; a sun-baked south façade makes the unit work harder. But shade never justifies boxing it in.
• Mount it solidly. Wall brackets rated for the weight, or a stable ground base. Vibration transmitted into a wall becomes a hum inside the flat — and inside the neighbour's.
• Think about the neighbours. Fan noise and warm exhaust aimed at the next balcony or a bedroom window is the origin of most AC disputes in apartment buildings.
• Leave service access. Someone has to reach it for cleaning and refrigerant checks. A unit hung where it needs scaffolding to service is a recurring cost.
• Plan for meltwater. In heating mode the unit produces meltwater during defrost cycles — worth planning for if you will heat with it in winter.

Distance between the units affects the price

The two units are joined by copper piping, and a standard installation typically includes only the first few meters. Every additional meter is charged per meter, and long runs also cost a little efficiency. Placing the indoor unit on an outside wall near where the outdoor unit will hang is the cheapest configuration; running pipes across an apartment to reach the opposite façade is the most expensive.

This is exactly why placement belongs in the budgeting conversation and not only the aesthetic one — the installation cost guide covers how piping length and difficult access change the final figure. Installers on ORVIA publish their per-meter copper price alongside their fixed installation prices, so you can check the effect of a longer run in your city before committing to a layout.

Apartments and balconies in practice

In most apartment buildings, the outdoor unit ends up on a balcony, a façade bracket, or a dedicated recess. A few local realities are worth checking before the installer arrives: whether the building has rules about façade-mounted units or a required position, whether an upper-floor façade mount needs access equipment (which adds to the price), and whether the balcony you had in mind is enclosed enough to cause the recirculation problem above.

If you are replacing an old unit, the existing position is the default but not automatically the best one — while the wall is open is the cheapest moment to correct a placement you never liked.

Decide it before you book, confirm it with the installer

Come to the installation with a preferred position for both units, the intended pipe route, and the drain route in mind. A good installer will confirm or adjust it on site — they can see wall construction, existing risers, and access that a plan cannot. What matters is that placement is a decision made together beforehand, not improvised with a hammer drill in hand. Compare installers and book AC installation in your city, or start from installers in Skopje.