Installation of a Fujitsu Aquila XLTH R32 dual-zone heat pump in Delson, on Montreal’s South Shore

An outdoor unit precisely installed on a wall bracket to better withstand Delson’s winter conditions

In Delson, on the South Shore of Montreal, we completed the installation of a Fujitsu Aquila XLTH dual-zone heat pump designed to heat and cool two distinct areas of the residence using a single outdoor unit. The project photograph highlights a fundamental aspect of our work at AirGreen: the quality of an installation is measured not only by the performance of the selected equipment, but also by the precision of the assembly, the stability of the support, and the accessibility of the components for years to come.

The Fujitsu AIRSTAGE R32 outdoor unit was mounted on a metal wall bracket anchored to the foundation. Blue anti-vibration pads were placed beneath the machine’s support points. A level is visible above the unit during the work, illustrating an essential installation step: we must confirm that the appliance is positioned correctly before finalizing the connections.

The exterior wall has two distinct materials: horizontal siding in the upper section and a stucco-covered foundation in the lower section. This configuration requires careful selection of the mounting points. The support must never rely solely on decorative siding. It must transfer the weight of the unit to a stable, suitable structure.

This heat pump installation in Delson was therefore designed to meet several objectives:

• keep the unit above snow and ice;
• limit the transmission of vibrations to the building;
• maintain sufficient clearance around the unit;
• make cleaning and maintenance easier;
• protect the refrigerant and electrical connections;
• provide two comfort zones without multiplying the number of outdoor units.

Why a dual-zone heat pump was suitable for this residence

A dual-zone heat pump uses a single outdoor unit to power two indoor units. Each indoor unit can be installed in a different space and controlled separately.

This configuration is particularly relevant when a home includes two areas with different needs, for example:

• a ground floor and an upper floor;
• an open-plan area and a bedroom;
• a room highly exposed to sunlight and a more shaded area;
• an extension and the main part of the residence;
• two distant spaces separated by a hallway or staircase;
• an area that is poorly served by the existing heating system.

In many homes in Delson, a single wall-mounted unit placed in a central area is not enough to ensure an even temperature. The conditioned air must pass through doors, partitions, and sometimes a change in level. By distributing the work between two indoor units, we can better target the spaces that are actually occupied.

The dual-zone system also helps reduce the amount of equipment outside. Rather than installing two separate condensers, we use a single multi-zone outdoor unit.

A clearly identified R32 Fujitsu AIRSTAGE unit

The photo clearly shows the Fujitsu, AIRSTAGE, and R32 markings on the front of the outdoor unit.

R32 is a refrigerant used in several recent HVAC systems. Its use requires appropriate procedures, instruments, and practices. The safety label visible on the nameplate also indicates the classification A2L, which is a mildly flammable refrigerant.

This characteristic should not be dramatized, but it must be taken seriously by the installer. An R32 installation requires, among other things:

• the use of compatible tools;
• appropriate ventilation during the work;
• precisely prepared refrigerant connections;
• a thorough leak check;
• a complete vacuum evacuation;
• compliance with the manufacturer’s requirements;
• commissioning performed by qualified technicians.

We never treat an R32 installation as a simple automatic replacement for an older system. The piping diameters, permitted lengths, refrigerant quantity, and electrical requirements must be confirmed for the exact model.

The wall bracket: a solution suited to Quebec winters

The Fujitsu unit was installed on a metal wall bracket rather than on a slab placed on the ground.

This decision offers several advantages for a residence on the South Shore.

Better protection against snow

An outdoor unit installed too low can quickly become surrounded by snow after a storm. If the heat exchanger or the lower part of the chassis is blocked, airflow decreases and the system may lose efficiency.

The wall-mounted support keeps the heat pump at a height that facilitates snow removal and reduces the risk of it being buried.

Better management of defrost water

During winter, the heat pump accumulates frost on its outdoor heat exchanger. It must periodically perform a defrost cycle to melt this buildup.

The water produced falls beneath the unit. An installation that is too close to the ground can gradually end up above a block of ice.

Raising the unit provides more space for drainage, although the ground and the area beneath the unit must still be monitored.

An installation independent of ground movement

Freeze-thaw cycles can shift some bases placed directly on the ground. A support properly secured to the foundation reduces this risk.

Stability nevertheless depends on the quality of the anchors, the building’s structure, and the choice of support.

Visible anti-vibration pads beneath the unit

The photograph shows blue pads installed beneath the feet of the outdoor unit.

These components serve an important purpose. The compressor and fan naturally produce some vibration during operation. When the unit is attached to the structure, part of this vibration can be transmitted to the building.

Under certain conditions, occupants may perceive a humming sound in a room on the other side of the wall, particularly at night.

Anti-vibration pads help limit this transmission. However, their effectiveness depends on the installation as a whole:

• rigidity of the support;
• quality of the anchors;
• leveling of the machine;
• position of the lines;
• contact with the wall;
• tightness of the fasteners;
• proximity to bedrooms.

We also check that the refrigerant lines are not rubbing directly against the foundation, since this contact can become another path for noise transmission.

Leveling the unit is not merely an aesthetic detail

The visible level above the heat pump reflects an important stage of the installation.

An outdoor unit must be positioned correctly for several reasons:

1. ensure good mechanical stability;
2. avoid uneven loads on the support points;
3. maintain the frame’s geometry;
4. facilitate the drainage specified by the manufacturer;
5. achieve a clean finish;
6. limit abnormal vibrations.

We do not rely solely on the lines of the exterior cladding. A façade can appear straight while having a slight slope, and the foundation parging can be uneven.

We therefore use a level before permanently tightening the fasteners.

A mounting system that respects the façade materials

The upper part of the wall is covered with horizontal siding. The lower part consists of a foundation covered with stucco.

The heat pump support must not be anchored only in the siding. The siding protects and covers the building, but is not necessarily designed to support the weight and vibrations of an outdoor unit.

We must locate a load-bearing structure and choose anchors suited to the material encountered.

An improperly designed mounting system can lead to:

• sagging of the support;
• excessive vibration;
• cracks in the stucco;
• deformation of the siding;
• misalignment of the unit;
• noise transmitted to the residence.

Our method consists of assessing the wall before drilling, selecting suitable anchor points, and checking the final rigidity of the support.

The technical characteristics and design decisions behind this multi-zone installation

Fujitsu Aquila XLTH: a range designed for multiple combinations

The Fujitsu AIRSTAGE Aquila range belongs to the H-series multi-zone systems. According to the documentation provided, Fujitsu offers 18,000, 24,000, 36,000, and 45,000 BTU/h outdoor units that can be combined with different indoor units.

Compatible unit types include:

• wall-mounted models;
• Slim Duct units;
• compact cassettes;
• Mid Static Duct units.

For a dual-zone configuration, the 18,000 BTU/h outdoor unit can be connected to two compatible indoor units. Page 2 of the Fujitsu document presents various combinations using 7,000, 9,000, 12,000, and 15,000 BTU/h units.

However, the photo does not make it possible to confirm with certainty the exact capacity of the installed unit. The outdoor dimensions may be similar from one model to another. The capacity must be verified using the complete model number, the quotation, and the nameplate.

Heating designed for cold conditions

The Aquila series documentation indicates that the cold-climate versions can operate in heating mode down to -26 °C.

This information is particularly important in Delson, where winter temperatures require a heat pump capable of continuing to produce heat well below freezing.

However, three concepts must be distinguished:

• the minimum operating temperature;
• the capacity actually available at that temperature;
• the residence’s heating load.

The fact that a unit can operate down to -26 °C does not automatically mean that it will cover 100% of each home’s heat loss on its own at that temperature.

We must consider insulation, windows, airtightness, and the auxiliary heating system.

Sizing is not limited to floor area

To select a dual-zone heat pump, we analyze each space separately.

The main factors include:

• floor area;
• ceiling height;
• the number of windows;
• solar orientation;
• insulation;
• the age of the building;
• exposed walls;
• air infiltration;
• the number of occupants;
• the presence of an open staircase;
• airflow between the zones.

Two 400 sq. ft. rooms may require different capacities. An open-plan area with several west-facing windows may accumulate much more heat than a shaded bedroom.

An oversized system may reach the setpoint quickly and run excessively short cycles. In cooling mode, this can reduce dehumidification.

An undersized system may run continuously without achieving the requested comfort during extreme conditions.

Understanding combinations exceeding 100% capacity

In some multi-zone configurations, the combined rated capacities of the indoor units may exceed the outdoor unit’s rated capacity.

Fujitsu indicates a connection capacity of up to 130 % may be permitted depending on the combination. However, the manufacturer clearly states that exceeding 100% does not increase the system’s maximum output.

For example, two indoor units may be technically compatible with an outdoor unit whose rated capacity is lower than their combined capacity. This configuration may be appropriate when the two zones do not reach their maximum load at the same time.

However, if both areas simultaneously demand their full capacity, the outdoor unit distributes its capacity between them.

An approved combination is not a load calculation

The manufacturer’s charts are used to confirm permitted combinations between units. They do not automatically determine the appropriate capacity for a home.

The documentation specifies that Fujitsu’s “Design Simulator” software should be used to select equipment for the H series.

Two separately controlled zones, but one shared mode

Each indoor unit can be controlled individually. Occupants can adjust separately:

• temperature;
• fan speed;
• shutters;
• schedules;
• startup.

The two units nevertheless share the same refrigerant circuit. They generally must operate in the same primary mode.

The system can heat both zones or cool them, but it normally cannot provide heating in one room while the other simultaneously calls for cooling.

Fujitsu documentation states that the system provides heating and cooling, but not both simultaneously.

This feature should be explained to occupants to avoid conflicting commands from the remote controls.

Inverter modulation in a dual-zone application

The inverter-driven compressor adjusts its speed according to demand.

When only one indoor unit is operating, the system can reduce its output. When both zones require more heating or cooling, it can gradually increase its operating rate.

This modulation promotes:

• more stable temperatures;
• longer cycles;
• fewer abrupt startups;
• quieter operation at partial load;
• consumption better suited to demand.

In a dual-zone installation, this flexibility is particularly useful because the two areas are not necessarily occupied at the same time.

Protecting the refrigerant lines

Although the lines are not visible in the front-facing photograph, they must be connected to the service side of the outdoor unit and protected along their route.

The system generally includes:

• two sets of copper piping;
• insulation;
• communication cables;
• certain electrical components;
• drainage from the indoor units.

In a multi-zone installation, each indoor unit has its own connection circuit to the outdoor unit.

Proper protection prevents:

• deterioration of the insulation;
• damage caused by ultraviolet rays;
• tool impacts;
• animal bites;
• water infiltration;
• thermal losses.

A complete commissioning after installation

Physically securing the unit is only part of the work.

Before startup, we notably perform:

1. checking the refrigerant connections;
2. a leak test;
3. a vacuum evacuation;
4. checking the electrical power supply;
5. confirming communication between the units;
6. starting each zone;
7. measuring system behavior;
8. inspecting vibrations and noises;
9. checking the indoor drainage.

Vacuum evacuation is essential for removing air and moisture from the lines. Rushing the commissioning process can affect compressor reliability and system performance.

Mistakes to Avoid with This Type of Outdoor Installation

Secure the unit only to the cladding

Exterior cladding is not necessarily load-bearing. The bracket must be anchored to an appropriate structure.

Install the unit too close to the ground

Snow, ice, and debris can obstruct the heat exchanger or drainage.

Neglect leveling

A tilted unit may be less stable and result in a poor finish.

Omit anti-vibration components

An overly rigid mounting can transmit more noise into the building.

Block the service side

The technician must be able to access the components and connections without dismantling permanent structures.

Enclose the unit under a poorly designed shelter

An enclosure that is too closed can cause discharged air to recirculate and reduce performance.

Push snow in front of the fan

The front clearance must remain unobstructed throughout the winter.

Recommended Maintenance After Installation

The owner must keep the area around the unit clear.

We specifically recommend:

• remove leaves and debris;
• trim vegetation around the bracket;
• clear snow after storms;
• do not place objects against the grille;
• monitor ice buildup;
• keep access to the service panel;
• visually inspect the pads and bracket.

Inside, the filters of both units must be cleaned regularly. A clogged filter reduces airflow and may make it seem as though the system lacks capacity.

An Installation Designed to Last in Delson

This Fujitsu Aquila XLTH dual-zone heat pump installation in Delson highlights several elements that directly influence the reliability of an HVAC system:

• a sturdy wall bracket;
• anchoring into the foundation;
• a height suited to winter conditions;
• anti-vibration pads;
• verified leveling;
• a clearly identified R32 unit;
• full front clearance.

At AirGreen, we install wall-mounted heat pumps, multi-zone systems, and central solutions in Montreal, Laval, Longueuil, the North Shore, and the South Shore.

Each project is adapted to the actual building. The façade type, expected snow depth, window placement, electrical access, and piping route influence our approach.

Our goal is to deliver a clean, stable, accessible HVAC installation suited to Quebec’s climate conditions, while giving occupants precise comfort control in each of the two zones.