Installation of a Fujitsu AIRSTAGE Aquila XLTH dual-zone heat pump in Blainville on the North Shore

A carefully executed indoor installation despite a visible line route and very precise wall space

In Blainville, our AirGreen team installed a Fujitsu AIRSTAGE Aquila XLTH dual-zone heat pump to heat and cool two distinct areas of the residence from a single outdoor unit.

The photograph of this project shows one of the wall-mounted units installed in a room where the choice of location had to account for several existing constraints: a large window, a curtain rod, a narrow wall corner, a textured ceiling, and a line route that could not be completely concealed within the structure.

Rather than leaving the refrigerant lines and wiring exposed, we created a clean route using a white interior line hide. It descends vertically near the window, changes direction in the upper section, and then runs horizontally to the Fujitsu unit installed near the ceiling.

The result is functional, accessible, and visually orderly. This type of finish is particularly important in a living room or bedroom, where every component of the installation remains visible on a daily basis.

Why did the lines have to remain indoors?

In an ideal installation, the lines can sometimes pass directly through the wall behind the indoor unit and reach the exterior almost immediately. However, the building’s configuration does not always allow this arrangement.

In this Blainville residence, the wall-mounted unit had to be installed on a section of wall far from the available exit point. The route therefore had to run along the interior wall before descending near the window.

Several reasons may require such routing:

• the wall structure;
• the position of the joists and studs;
• the location of the outdoor unit;
• façade constraints;
• the presence of a window;
• the inability to pass through an adjacent wall;
• the need to maintain a drainage slope;
• the configuration of the system’s two zones.

Our role was to organize this routing so it would not look improvised. The line-hide sections were installed with clean angles, suitable connections, and alignment consistent with the room’s architectural lines.

An indoor line-set cover is not used solely for aesthetic purposes

The line-set cover visible in the photo groups and protects the technical components connecting the indoor unit to the rest of the system. Depending on the exact configuration, it may contain:

• the insulated copper refrigerant lines;
• the interconnection wiring;
• the communication conductors;
• the condensate drain hose;
• certain mechanical protection components.

Without a line-set cover, the insulated lines would remain exposed on the wall. They would be more vulnerable to impacts, wear, sunlight near the window, and accidental handling.

The line-set cover also facilitates future maintenance. When an inspection of the routing is required, the sections can be opened without demolishing the wall.

In this project, the white line-set cover matches the window frame, the Fujitsu indoor unit, and the ceiling. This consistency reduces its visual impact, even though the routing necessarily remains visible.

A wall-mounted unit installed near the ceiling, but with the proper clearance

The indoor heat pump is installed high up to promote air distribution throughout the room. Its location also preserves usable space around the furnishings.

However, a wall-mounted unit should never be installed flush against the ceiling. Most models draw in room air through their upper section. Insufficient clearance can restrict air intake and impair operation.

We need to maintain enough space to:

• allow air intake;
• open the front panel;
• remove and clean the filters;
• access the components during maintenance;
• prevent excessive dust buildup in a space that is too confined.

The photograph shows that the unit is installed near the ceiling without being wedged against it. This positioning makes effective use of the available height while maintaining the necessary access.

The window’s proximity required particular attention

A window directly influences a room’s thermal behavior. It can be a source of heat gain in summer and heat loss in winter.

Installing an indoor unit nearby can be advantageous, as the airflow helps quickly compensate for these variations. However, several mistakes should be avoided.

The unit must not:

• be blocked by the curtains;
• blow directly onto a curtain rod or blind;
• be installed too close to the frame;
• prevent the window from opening;
• direct air at the glazing from very close range;
• make filter cleaning difficult.

In this Blainville project, the unit was placed on the wall adjacent to the window, above the horizontal path of the line-hide cover. The curtain rod remains on the opposite side and does not directly block the airflow.

The vertical path was also positioned to preserve the framing and avoid interfering with normal window use.

Why choose a dual-zone heat pump?

A dual-zone heat pump uses a single outdoor unit to power two indoor units. Each serves a specific area of the property.

This solution is particularly relevant when airflow between rooms is limited. A single unit installed in a central area may have difficulty maintaining the same temperature in a closed bedroom, on another floor, or in a remote section.

With two zones, occupants can adjust the following separately:

• temperature;
• fan speed;
• louver direction;
• operating periods;
• turning a zone on or off.

Fujitsu documentation on H-series AIRSTAGE multi-zone systems indicates that each indoor unit can be controlled independently using its remote control. However, it specifies that the system provides either heating or cooling and cannot operate both modes simultaneously in different zones.

What independent control really means

The two units can have different setpoints, but they share the same outdoor unit and the same overall mode.

For example, it is possible to:

• cool one zone to 22°C and the other to 24°C;
• heat one room to 20°C and the other to 22°C;
• operate only one unit;
• use different fan speeds;
• temporarily shut off a lightly occupied zone.

It is not possible to request heating in one zone and cooling in the other simultaneously.

This characteristic must be understood from the outset, as it affects how the system is used during transitional periods, particularly in spring and fall.

Fujitsu AIRSTAGE Aquila XLTH: a flexible multi-zone range

The Fujitsu AIRSTAGE Aquila range is designed to accommodate various residential configurations. According to the manufacturer’s documentation, the H-series outdoor units are available in nominal capacities of 18,000, 24,000, 36,000, and 45,000 BTU/h.

They can be paired with several styles of indoor units:

• Wall-mounted units;
• Slim Duct concealed units;
• Compact cassettes;
• Mid Static Duct units.

This flexibility makes it possible, when the project requires it, to combine a wall-mounted unit in one room with a more discreet unit in another zone. For this installation in Blainville, the wall-mounted solution suited the available space and allowed direct air distribution.

Page 2 of Fujitsu’s documentation presents the different outdoor units and the authorized combinations. The 18,000 BTU/h model can, in particular, be connected to two indoor units, corresponding to a dual-zone configuration.

Possible capacity combinations

For the AOUH18KWAS2 and AOUH18KWAH2 dual-zone outdoor units, Fujitsu lists several authorized nominal combinations, including:

• 7,000 + 7,000 BTU/h;
• 7,000 + 9,000 BTU/h;
• 7,000 + 12,000 BTU/h;
• 7,000 + 15,000 BTU/h;
• 9,000 + 9,000 BTU/h;
• 9,000 + 12,000 BTU/h;
• 9,000 + 15,000 BTU/h;
• 12,000 + 12,000 BTU/h.

These options make it possible to match the capacity of each indoor unit to the needs of the zone it serves.

A larger open area may require a higher-capacity unit than a bedroom or office. The two units therefore do not necessarily need to be identical.

Why combination tables do not replace load calculations

A manufacturer’s table confirms that a combination of units is technically permitted. It does not confirm that this combination meets the building’s actual needs.

Fujitsu also specifies that its tables are not intended to select system capacity and recommends using the Design Simulator software for H-series AIRSTAGE equipment.

At AirGreen, we consider several factors before proposing a combination:

• the area of each zone;
• ceiling height;
• the number of windows;
• solar orientation;
• insulation;
• the building’s airtightness;
• the presence of an upper floor;
• how each room is used;
• the number of occupants;
• winter heat losses;
• summer heat gains.

Area alone is not enough. A heavily glazed south-facing room may require more cooling than a room of the same size facing north.

Connected capacity up to 130%: a figure that must be interpreted correctly

Fujitsu documentation indicates that certain multi-zone outdoor units accept a connected capacity of up to 130 %. This means that the total nominal capacity of the indoor units can sometimes exceed the outdoor unit’s nominal capacity.

This flexibility can be useful when the two zones do not reach their maximum demand at the same time.

However, a potential misinterpretation should be avoided: Fujitsu specifies that a combination exceeding 100% does not increase the outdoor unit’s actual production capacity.

If both indoor units require full capacity simultaneously, the available capacity must be distributed. Proper selection must therefore take into account the actual use of the spaces, not just the total capacity displayed on the indoor units.

A heat pump suited to Blainville’s climate

In Blainville, winter temperatures can be low enough to require a heat pump designed for cold climates.

Fujitsu documentation presents the Aquila CTEB units as capable of providing heating down to -26 °C and cooling up to 50 °C.

The system uses an inverter-driven compressor. This type of operation allows production to be modulated according to demand.

Rather than constantly alternating between full power and a complete shutdown, the compressor can slow down when a zone approaches its setpoint.

This modulation helps:

• maintain a more stable temperature;
• reduce abrupt fluctuations;
• better match the capacity when only one zone is operating;
• limit some repeated starts;
• adjust production to changes in load.

In a dual-zone system, this adaptability is important because demand can vary continuously between the two spaces.

Drainage: an often-invisible constraint in the photo

In air conditioning, the indoor unit removes moisture from the air. This water must be discharged through a drain.

The drain pipe can run inside the line set cover visible on the wall. Its installation must maintain a constant slope when drainage relies on gravity.

An inadequate slope can cause:

• water accumulation;
• gurgling;
• backflow;
• a leak beneath the unit;
• marks on the wall;
• odors coming from the condensate pan.

The visible route includes a horizontal change of direction followed by a vertical one. This type of configuration must be carefully planned to maintain reliable drainage.

When gravity does not allow adequate drainage, a condensate pump may be necessary. However, natural drainage generally remains preferable when feasible, since it involves fewer mechanical components.

The challenge of angles and connections in a line set cover

The finish of a line set cover depends greatly on the quality of the directional changes.

In the photo, the route includes:

1. an outlet near the unit;
2. a long horizontal section;
3. an elbow in the upper corner;
4. a vertical drop;
5. a transition to the outlet point.

Each connection must be adjusted to prevent gaps, visible spaces, and poorly aligned sections.

A poorly installed line-hide can look disorganized even when the heat pump is operating properly. It can also vibrate, come loose, or place pressure on the lines.

Our goal is to protect the technical connections while creating a route that is as discreet as possible.

Why not hide the lines in the wall at all costs?

Some homeowners want all the lines to be completely concealed. This solution is not always the safest choice.

Concealing the lines in a wall may require:

• opening the drywall;
• modification of the interior finish;
• painting work;
• structural penetrations;
• more complex access in the event of a repair;
• coordination with other trades.

In many cases, a clean line-hide offers a better balance between appearance, cost, accessibility, and protection.

For this Blainville residence, the exposed routing keeps the lines accessible and avoids much more extensive interior finishing work.

Checks performed before commissioning

An HVAC installation is not complete when the equipment is simply mounted on the wall. We perform several checks before handing the system over to the occupants.

Wall plate inspection

The unit must be securely seated on its support and perfectly stable.

Top clearance inspection

The air intake and panel opening must remain accessible.

Line-hide inspection

The sections must be secured, aligned, and free of vibrations.

Drainage inspection

We confirm that condensate drains without leaks or backup.

Refrigerant connection inspection

The connections must be leak-tight and the lines properly insulated.

Vacuuming

Air and moisture must be removed from the circuit before commissioning.

Electrical inspection

The wiring and communication between the two indoor units and the outdoor unit are tested.

Testing both zones

Each unit is tested separately, then the system is observed while both zones are operating.

Louver and airflow control

The airflow must remain unobstructed and properly reach the room.

Mistakes to avoid when routing lines indoors in plain view

This project illustrates several common mistakes.

1. Installing the line-hide without planning for drainage
   Appearance should never compromise condensate drainage.
2. Positioning the line set too close to the curtain rod
   The curtains must be able to open and close normally.
3. Using too many small fittings
   A more direct route generally produces a better finish.
4. Leaving the lines unprotected
   Exposed insulation deteriorates and may be damaged.
5. Installing the unit too close to the ceiling
   Air intake and access to the filters may be reduced.
6. Neglecting the alignment of the line-hide
   A slightly sloped section becomes highly visible along a ceiling or window.
7. Blocking future access to the connections
   The finish must remain removable for maintenance.
8. Choosing the capacity solely according to the unit’s physical size
   The system capacity must meet the zone’s heating and cooling needs.

Operating tips for a Fujitsu dual-zone heat pump

To ensure stable and comfortable operation, we recommend that occupants:

• select the same general mode on both units;
• avoid extreme temperature differences between two open zones;
• let the inverter compressor modulate rather than turning it on and off frequently;
• clean the filters regularly;
• keep the air inlets and outlets clear;
• prevent the curtains from touching the unit;
• watch for any sign of moisture near the line-hide;
• request HVAC maintenance if the airflow decreases or an unusual noise appears.

The line-hide does not require frequent maintenance, but its sections must remain closed and securely fastened. Any sign of water nearby should be inspected promptly.

An HVAC installation adapted to the residence’s actual architecture

This installation of a Fujitsu AIRSTAGE Aquila XLTH dual-zone heat pump in Blainville illustrates a common situation: the ideal location for comfort does not always correspond to the simplest route for the lines.

Our team therefore designed a protected indoor route that neatly goes around the corner of the room, follows the wall, and reaches the unit without obstructing the window or curtain rod.

At AirGreen, we install wall-mounted heat pumps, dual-zone systems, and multi-zone systems in Montreal, Laval, Longueuil, the North Shore, and the South Shore. Each project is assessed according to heating and cooling needs, as well as the architecture, drainage, aesthetics, maintenance access, and actual routing of the lines.

A successful installation must remain reliable behind its polished appearance. In this Blainville residence, the Fujitsu Aquila XLTH solution now makes it possible to control two separate zones while maintaining a clean interior finish and convenient access to the technical components.