AC Lines: Running and Hiding Them Before Finishing

Why split AC refrigerant, drain and power lines should be installed before finishing, plus unit positions, drain gradient and testing.

A freshly chased groove in a newly decorated wall, or a white plastic trunking running down from the ceiling, usually has the same cause: the air conditioner was thought about after the renovation ended. Running the lines that connect a split system's indoor and outdoor units inside the wall before finishing is both neater and more reliable. It does, however, require a few decisions to be made early.

Which lines go in at rough-in stage

A split air conditioner needs several connections between the indoor and outdoor units:

• two copper pipes carrying refrigerant in liquid and gas form, each with thermal insulation;
• a control and power cable linking the units;
• a condensate drain pipe from the indoor unit;
• a dedicated power circuit from the electrical panel.

During the renovation these lines are run through the wall, with enough spare length left at each end to connect the units later. The ends of the copper pipes are sealed to keep dust and moisture out.

Unit positions: decide first, chase later

The first condition for concealed installation is knowing exactly where the indoor unit will go. It should not blow air directly onto a bed or desk, must not clash with curtain tracks or ceiling cornices, and should allow air to spread freely around the room. The clearances above and beside the unit required by the manufacturer must be kept.

The outdoor unit's position matters just as much. In apartment buildings, rules for mounting units on the facade may be set by the building management; some buildings provide dedicated cages or service balconies. The unit must not blow hot air into a neighbour's window, drain water must not drip onto a footpath, and the unit must be accessible for servicing.

The distance and height difference between indoor and outdoor units must stay within the manufacturer's limits. If the pipe run is long, the system may need topping up with refrigerant, so agree this with the installer beforehand.

The drain: the most troublesome part

In cooling mode an air conditioner removes moisture from the air, and this water leaves through the drain pipe. Because the drain works by gravity without pressure, the pipe needs a continuous fall along its whole length. If it rises or sags at any point, water collects there and eventually drips from the indoor unit.

Options for where the drain can go:

• to the facade, where building rules allow;
• into the waste pipe, always through a trap or a dry waterless trap so odours cannot return;
• via a small condensate pump where a gradient cannot be achieved.

A condensate pump makes some noise and needs periodic servicing, so in a bedroom it is best treated as a last resort.

Concealing in the wall: what to watch

Lines can run in a chase or behind a plasterboard lining. In either case:

• flare joints on the copper pipes should not be left inside the wall; where possible a continuous length is used;
• insulation must be continuous along the pipe with joints taped, or condensation will form on the pipe surface;
• refrigerant pipe must be bent with a proper tool, without kinking;
• keep a gap between the power cable and the drain.

When the outdoor unit is replaced or the system repaired, you will need to know how the line runs inside the wall. So the route is photographed with measurements before the wall is closed.

Testing and sign-off

Once the lines are in and the units installed, the refrigerant circuit is checked for tightness, evacuated and only then started. At renovation stage, before the units are mounted, at least the drain pipe should be tested by pouring water through it, and the copper pipe ends must remain sealed.

Questions worth asking at handover:

• are the line routes documented with photos and a drawing;
• does the drain fall along every section, and was it tested with water;
• is the power circuit protected by its own breaker in the panel;
• will the spare length at the wall outlets reach the unit position.

These steps prevent damage to finished walls when the air conditioner is installed later.

Zaferoğlu İnşaat plans air conditioning, electrical and plumbing lines together during the rough-in phase of apartment renovations. It is far easier to agree air-conditioning routes with us on the plan before the walls are plastered.