Installation of a Fujitsu Aquila XLTH dual-zone heat pump in Acton Vale

A Fujitsu wall-mounted unit precisely integrated near a window, a curtain, and ceiling molding

For this Fujitsu Aquila XLTH dual-zone heat pump installation in Acton Vale, our AirGreen team had to find a location capable of meeting three requirements that are not always easy to reconcile: good airflow, a discreet indoor installation, and a clean technical route to the outdoors.

The photograph shows one of the Fujitsu AIRSTAGE indoor units installed very high on the wall, immediately beside a window and its curtain. The ceiling also has substantial decorative molding that reduces the available space above the unit. On the left side, a darker section of wall and an architectural return further limit the positioning options.

In a similar situation, it is not enough to choose an unobstructed wall. We must check the unit’s height, its clearance from the ceiling, the opening of the front panel, the path of the airflow louver, and especially its interaction with the curtains. The goal is for the heat pump to draw in and distribute air normally without the fabrics interfering with its operation.

The result is a compact installation that makes smart use of the upper portion of the wall while preserving living space.

A dual-zone heat pump for conditioning two areas with a single outdoor unit

The principle of a dual-zone heat pump is particularly useful when a home includes two spaces with different comfort needs.

A single Fujitsu outdoor unit powers two indoor units. Each can be controlled separately, making it possible to set a different temperature in each room.

Such a configuration can be used, for example, to serve:

• a living room and a bedroom;
• a ground floor and an upper floor;
• a main living area and an extension;
• a bedroom and an office;
• two opposite areas of the house.

For this installation in Acton Vale, the unit visible in the photo serves one of the two zones. The system therefore avoids the need for two separate outdoor units while maintaining individual indoor control.

Fujitsu documentation states that H-series AIRSTAGE multi-zone systems allow each indoor unit to be controlled independently. The system provides heating and cooling, but not both simultaneously: the different zones must share the same primary mode.

A location near a window: worthwhile, but requiring proper analysis

Installing a wall-mounted unit near a window can be worthwhile, particularly because windows are often a major source of heat gain and heat loss.

In winter, the glazing can create a cold-wall sensation. In summer, solar exposure can quickly increase the room’s temperature.

A nearby heat pump can help effectively manage these variations, provided its airflow remains unobstructed.

In this installation, we had to pay particular attention to three elements:

• the curtain’s proximity;
• the moulding at ceiling level;
• the unit’s final height.

The curtain must never block the unit

The curtain visible on the right hangs very close to the heat pump. This detail is important because a lightweight fabric can move with the airflow produced by the unit.

If the curtain is drawn toward the air intake or blown against the louver, several problems may arise:

• reduced airflow;
• additional noise;
• less representative temperature readings;
• uneven air distribution;
• contact between the fabric and moving parts;
• faster dust accumulation.

During daily use, the curtain must therefore remain sufficiently far from the unit.

It is also preferable to avoid having a thick curtain partially cover the side of the heat pump when it is fully open.

The ceiling moulding required a very precise height

The photograph shows a fairly wide decorative moulding along the upper part of the wall. It reduces the usable height and creates an offset that had to be taken into account before mounting the wall plate.

The indoor unit draws a significant portion of its air from above. A device placed too close to the ceiling or a bulky moulding may have restricted air intake.

A reduction in airflow can lead to:

• reduced capacity;
• increased noise;
• longer cycles;
• less effective filtration;
• increased consumption;
• less consistent comfort.

The unit’s position was therefore chosen to make maximum use of the available height without compromising its operation.

Access to the front panel also had to be maintained

A compact installation must never make filter removal impossible.

The front panel must be able to open far enough to allow:

• filter cleaning;
• coil inspection;
• access to the internal components;
• periodic maintenance;
• a possible repair.

A few extra centimetres that are poorly planned during installation can make this work unnecessarily complicated throughout the system’s entire service life.

The airflow louver and air distribution in the room

The lower louver visible in the photo is in the open position. It directs air toward the occupied space.

The installation height facilitates airflow over a greater distance. The air should not simply fall directly beneath the unit; the goal is to create circulation throughout the area.

In cooling mode, more horizontal airflow often helps cool air travel through the room before naturally descending.

In heating mode, the direction can be adjusted more downward to send warm air toward the occupied area.

The unit’s proper placement must therefore take into account not only the wall on which it is mounted, but also:

• the position of the bed or sofa;
• doors;
• tall furniture;
• windows;
• curtains;
• areas where occupants spend long periods.

A properly sized heat pump can nevertheless cause discomfort if its airflow is constantly directed toward a person who is sitting or lying down.

The role of the Fujitsu Aquila XLTH system in cold climates

The documentation provided for the Fujitsu AIRSTAGE Aquila and Aquila CTEB systems presents several H-series outdoor units.

The listed nominal capacities include:

• 18,000 BTU/h;
• 24,000 BTU/h;
• 36,000 BTU/h;
• 45,000 BTU/h.

Depending on the model, an outdoor unit can be connected to two, three, four, or five indoor units. Fujitsu also offers several evaporator styles: wall-mounted units, Slim Duct, compact cassettes, and Mid Static Duct units.

For cold-climate versions, the documentation mentions heating operation down to -26 °C.

This feature is particularly relevant in Quebec, where a heat pump should not be evaluated solely on its summer performance.

Fujitsu’s dual-zone combinations

For the 18,000 BTU/h outdoor unit shown in the Fujitsu table, several combinations with two indoor units are permitted, 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.

This information does not mean that the photographed installation necessarily has one of these exact capacities. The indoor unit’s nameplate is not clear enough in the photo to identify its BTU rating with certainty.

Fujitsu also specifies that its combination tables should not be used alone to select capacity. The manufacturer recommends its Design Simulator software for selecting H-series AIRSTAGE equipment.

The connected capacity can exceed 100%, but this detail must be understood

One of the interesting aspects of multizone systems is the possibility of installing a total indoor capacity greater than the outdoor unit’s rated capacity in certain combinations.

Fujitsu indicates a connection capacity of up to 130 % on the multizone systems concerned.

This possibility can be very useful when the zones do not reach their maximum load at exactly the same time.

However, this does not mean that an 18,000 BTU/h outdoor unit suddenly becomes capable of producing 24,000 BTU/h simply because the two indoor units total that amount.

The manufacturer explicitly states that exceeding 100% in combination does not increase the system’s output capacity.

When both zones require substantial heating or cooling simultaneously, the available capacity must therefore be distributed.

Why load calculation remains essential

The ideal number of BTUs cannot be determined solely from the number of square feet.

We must consider:

• actual floor area;
• insulation;
• number of exterior walls;
• window type;
• solar exposure;
• ceiling height;
• air infiltration;
• adjacent rooms;
• how the zone is used;
• the needs of the second indoor unit;
• the outdoor unit’s capacity.

In the room shown in the photograph, the window may account for a significant portion of the heat load. Its orientation and exposure to sunlight therefore matter more than a simple measurement of floor area.

An oversized system is not necessarily more comfortable

A common mistake is choosing more BTUs “to be safe.”

An oversized unit can cool the room very quickly, then greatly reduce its operation before removing enough moisture.

In summer, this can result in a room that is cool but too humid.

Sizing should aim for steady, modulated operation rather than a succession of very short starts.

A carefully executed installation, right down to the invisible details

Routing the lines behind the unit

In the photograph, the lines do not visually dominate the installation. This is exactly what we are looking for when a route can be completed discreetly.

A wall-mounted unit nevertheless requires several connections:

• liquid refrigerant line;
• gas refrigerant line;
• communication cable;
• power supply according to the configuration;
• condensate drain;
• pipe insulation.

The exit point behind or near the unit must be planned before securing the wall plate.

An error of just a few centimeters may require:

• decenter the unit;
• add an unnecessary line set cover;
• create a bend that is too tight;
• compromise the drain's slope;
• change the unit's final position.

The condensate drain must work without compromise

In air-conditioning mode, water forms on the indoor coil.

This water is collected and then discharged through a drain.

Poor drainage can cause:

• a leak beneath the unit;
• marks on the wall;
• a musty odor;
• water accumulating in the pan;
• damage to the paint or flooring.

When the drain operates by gravity, it must maintain a consistent slope to the drainage point.

When installing near a window and decorative elements, precise routing is particularly important to prevent damage that is difficult to repair.

Vacuum Pumping: An Essential Step Never Seen in the Final Photo

A professional HVAC installation is not limited to the appearance of the assembly.

Before commissioning, the refrigeration circuit must be properly prepared.

Vacuum pumping removes:

• air;
• moisture;
• non-condensable gases.

An installation left with moisture in the circuit may experience oil contamination and long-term deterioration.

We also check the tightness of the connections before commissioning.

These steps are invisible once the installation is complete, but they play a major role in the compressor's lifespan.

The Inverter Compressor and Comfort in Both Zones

Fujitsu documentation indicates the use of an inverter-driven compressor.

This technology varies the compressor speed according to demand instead of operating only at full capacity.

In a dual-zone system, this is particularly useful when:

• only one zone requires heating;
• the second is approaching its setpoint;
• both rooms require low capacity;
• needs change throughout the day.

Modulation helps maintain a more stable temperature and avoid certain unnecessary cycles.

The operation of the two zones must be clearly explained

Each indoor unit can have its own temperature, but the system remains shared.

For example, one zone can be set to 21 °C and the other to 23 °C in heating mode.

However, it is not possible to request heating in one room and air conditioning in the other at the same time.

This distinction is important for homes where the two zones have very different orientations.

A very sunny room may need cooling while another remains cool. Zone selection and daily use must therefore be considered from the outset.

Mistakes to avoid when installing near a curtain

Allowing the curtain to touch the unit

It may be drawn toward the filter or disrupt airflow.

Installing the unit too close to the ceiling

Air intake and filter access may become insufficient.

Forgetting the molding

A decorative molding can further reduce clearance compared with the ceiling itself.

Constantly directing air at the bed or sofa

Perceived comfort can be poor even if the ambient temperature is correct.

Choosing capacity based solely on floor area

Windows and solar exposure can significantly change the actual requirement.

Installing oversized indoor units simply because the combination is permitted

A technically approved combination does not automatically mean it is suitable for the building.

Regular indoor unit maintenance

The filters should be cleaned periodically to maintain good airflow.

In a room with curtains, textiles, and furniture, fibers can accumulate on the filters over time.

A heat pump maintenance service should notably include:

• filter cleaning;
• coil inspection;
• fan check;
• drain inspection;
• examination of visible connections;
• inspection of the outdoor unit.

It is also recommended to regularly check that the curtain has not shifted against the unit.

An installation designed for everyday comfort in Acton Vale

This Fujitsu Aquila XLTH dual-zone heat pump installation in Acton Vale clearly illustrates the importance of working with a room’s actual architecture.

The indoor unit had to fit between a ceiling molding, a wall corner, and a curtain. We used the upper part of the wall to preserve living space while maintaining effective air distribution.

The shutter remains fully functional, the panel stays accessible, and the unit blends naturally with the room’s light-colored finish.

The dual-zone system can simultaneously serve a second space with the same outdoor unit while giving each zone its own control.

At AirGreen, we install multi-zone heat pumps, wall-mounted air conditioners, and complete heating and cooling systems in Acton Vale and throughout Greater Montreal, including Montreal, Laval, Longueuil, the North Shore, and the South Shore.

Each project requires an analysis of the building, windows, furnishings, architectural constraints, and refrigerant line routing. A clean installation should be just as logical behind the wall as it is in front of it.

It is this planning that allows a Fujitsu heat pump to provide consistent comfort while blending discreetly into the home.