Air conditioning pre-installation in a new build: boxes, ducts, drainage and electrical circuit

Are you building a house, a villa or an apartment block in Morocco? This is the best time to think about air conditioning, even if you will only buy the units later. A well-done air conditioning pre-installation during the structural work avoids trunking on the walls, pipes dripping down the facade and chases cut into brand-new plaster. In this guide, Brico MIM explains step by step how to prepare a house build with AC: positions, AC pre-installation box, ducts, condensate drainage and electrical circuit, whether your site is in Casablanca, Tangier, Agadir, Oujda, Nador or Driouch.

Why pre-install AC during construction?

Pre-installation is all the work done before the air conditioner arrives: planning the route for the lines between the indoor and outdoor units, the condensate drainage and the power supply, with a clean connection point in the wall. On installation day, the technician mounts the units and connects them.

• An invisible result: everything runs inside the wall, behind the indoor unit. No white trunking on the paintwork and no pipe hanging down the facade.
• No work afterwards: drilling and redoing finished plaster costs time and dust, and is often more expensive than planning from the start.
• Freedom for later: you can equip one room straight away and the others in a year or two, since the connections are already in place.
• A home that is easier to sell or rent: rooms pre-equipped for AC are a real selling point.

Step 1: decide on the positions

Everything starts with the plan. Before the chases are cut, decide for each room to be air-conditioned:

• where the indoor unit will go: high on a clear wall, preferably on a short side so it blows along the length, not aimed straight at a bed or sofa, and leaving the space below the ceiling required by the appliance manuals;
• where the outdoor unit will go: terrace, roof, balcony or rear facade, in the shade if possible, well ventilated, accessible for maintenance and not disturbing the neighbours;
• the route between the two: as short and direct as possible, with few bends;
• where the condensate water will go: to a downpipe or drain, with a continuous slope.

To estimate the capacity room by room, use our guide Which capacity (BTU) and which type of air conditioner to choose. The table below sums up what to plan and at what stage of the build:

Step 2: the flush-mounted pre-installation box

The AC pre-installation box is a housing set into the wall at the exact position of the indoor unit. It brings together the power supply and the condensate drain in one place (and, depending on the model, the line passage). Once the split is hung, it is hidden behind it. We offer two Solera boxes in our electrical boxes range:

How to fit it

• During structural work, when the chases are cut and before plastering.
• Front flush with the finished wall surface: allow for the plaster thickness so the cover closes properly once the wall is finished.
• At the final position of the indoor unit: it is best to fix this position at that stage with your refrigeration technician.
• Open only the entries you need (on ref. 178): power, lines, drainage; the others stay closed.
• Point the drain outlet towards the downpipe: on ref. 178, it can be fitted on either side.

For the other boxes on site (junction, flush-mounting, waterproof), see our guide Electrical boxes: junction, flush-mounting, waterproof.

Step 3: ducts and refrigerant lines

Between the indoor and outdoor units run two insulated copper pipes (the refrigerant line) and an interconnection cable. In a new build, there are two approaches:

Leave an empty sleeve in place

A sufficiently wide sleeve (conduit) is embedded between the box and the exit point towards the outdoor unit. On installation day, the technician pulls through the lines suited to the chosen unit. This is the most flexible solution if you have not yet chosen your air conditioners; the diameter and route must be approved with the technician, as insulated lines are hard to pull through a narrow or heavily bent sleeve.

Lay the copper lines during structural work

The technician lays the insulated pipes directly in the wall, capped at both ends so no dust or moisture gets in. The diameters depend on the unit's capacity: so this should be done once the model, or at least the capacity, is known.

In both cases: a short route, gentle bends, no crushing under the screed, and an outer-wall passage sloping slightly outwards so rainwater cannot get in.

Step 4: condensate drainage

When cooling, an air conditioner produces water continuously. This water must drain by gravity, with a steady slope and no low point where it could sit:

• connect the box drain to a downpipe or a drain intended for this purpose;
• keep a continuous slope along the whole route, with no reverse slope;
• if connecting to a wastewater drain, fit a trap to prevent odours coming back up;
• do not discharge the water down the facade, onto the pavement or onto the neighbours;
• if a slope is impossible (unit under a beam, basement room), a condensate pump will be needed: plan it with the technician.

Step 5: the electrical circuit and panel

Each air conditioner must be powered by its own circuit, protected at the panel. The cable size and breaker rating depend on the unit's power: the electrician sizes them, with suitable residual-current protection. The basics are explained in our article Circuit breakers and RCDs.

• Reserve modules in the panel for future air conditioners, even if some rooms will only be equipped later.
• Choose a big enough enclosure: for example the Hager flush-mounted 24-module enclosure VF-212-TF (390 DH) rather than a 12-module one that is too tight. For a floor or an extension, a sub-distribution board such as the Hager 12-module enclosure VF112PF (220 DH) can group the AC circuits. The full range is in our electrical enclosures section; for help choosing, read Electrical enclosure and panel: choosing and sizing.
• Outdoors, connections exposed to the weather go in a waterproof box, such as the LAP waterproof box 180 × 140 × 80 mm (20 DH). Depending on the installation, the electrician may also fit an isolating switch near the outdoor unit.
• Check your subscription: if several air conditioners will run at the same time, have the contracted power checked.

For safety, never connect an air conditioner to a socket or a circuit that is already loaded, and leave electrical work to a qualified electrician.

Ducted and cassette systems

For a villa or a large apartment, you may be considering ducted air conditioning (in the false ceiling, with grilles in each room) or ceiling cassettes. Here, pre-installation goes further: enough false-ceiling height, access hatches, air duct routes, positions of supply and return grilles, and condensate drainage from the ceiling. All of this is decided at the plan stage, with a study. These units are sold on quote at Brico MIM, for example the Carrier ducted Inverter R32 24,000 BTU. The principle is explained in our article Ducted air conditioning for a villa in Morocco.

Checklist and mistakes to avoid

Frequently asked questions

How much does an AC pre-installation box cost?

At Brico MIM, Solera AC pre-installation boxes cost 50 DH each (current prices on the product pages). That is very little compared with the work they save later.

Can I pre-install without having chosen the air conditioner?

Yes: the box, condensate drainage, electrical circuit and an empty sleeve can be installed before choosing the unit. Only the copper lines and the exact protection rating depend on the model; at least decide on the planned capacity for each room.

Who should carry out the pre-installation?

The mason or electrician sets the boxes and ducts, the electrician wires the circuits, and the refrigeration technician approves the positions and routes, then installs and commissions the units. Any work on the refrigerant circuit must be done by an equipped refrigeration technician.

What about a house that is already built?

It is possible during a renovation, by opening the walls in the right place before re-plastering. Otherwise, the split is installed with visible trunking.

Do you deliver everywhere in Morocco?

Yes, Brico MIM delivers to every city in Morocco, with cash on delivery.