A multizone installation completed in an outdoor space already occupied by another Fujitsu system
In Charlemagne, we installed a Fujitsu Aquila XLTH dual-zone heat pump to serve two distinct areas of the home with a single outdoor unit. This project presented a particularly interesting constraint: the exterior wall already housed another Fujitsu heat pump, which reduced the space available for the new unit, its electrical supply, and the routing of its refrigerant lines.
The installation photograph clearly shows the new Fujitsu AIRSTAGE system using R32 refrigerant, mounted on a metal wall bracket above the ground. To its left is an existing Fujitsu Halcyon system, also elevated. Between the two units, the electrical disconnects are grouped on the wall, while the new system’s lines are protected inside a white line-set cover installed on the foundation.
In this configuration, it was not enough to find an open surface on which to mount the heat pump. We had to maintain the required clearances around both units, preserve access to the electrical components, avoid blocking the basement window, and plan for the drainage of water produced during defrost cycles.
The result is a compact, well-structured HVAC installation adapted to Charlemagne’s winter conditions.
Why choose a dual-zone heat pump for this home
A dual-zone heat pump consists of an outdoor unit connected to two indoor units. Each of these units serves a specific zone and can have its own temperature setting.
This configuration is particularly suitable when a home has two spaces with different needs, for example:
- a ground floor and an upper floor;
- a living room and a primary bedroom;
- an older section and an addition;
- an open-concept area and a more enclosed space;
- two distant rooms that cannot be properly served by a single wall-mounted unit.
In a home where a heat pump is already installed, adding a dual-zone system can also help target areas that remained less comfortable without immediately removing the existing equipment.
However, the building’s electrical capacity, the available outdoor space, and the required routes for the two new indoor units must be assessed. Adding a system does not simply involve placing a second machine next to the first.
A Fujitsu AIRSTAGE R32 unit installed on a wall-mounted support
The new heat pump visible in the photo bears the Fujitsu, AIRSTAGE, and R32 identifiers. The unit was installed on a metal support fastened to the foundation rather than placed directly on the ground.
This method offers several advantages in the Charlemagne area, where snow accumulation and freeze-thaw cycles must be taken into consideration.
By keeping the unit above the ground, we reduce the risk that:
- snow obstructs the air intake;
- ice accumulates immediately beneath the chassis;
- the unit is exposed to mud splashes;
- landscaping work damages the lines;
- the base shifts as a result of ground frost.
The support also includes pads installed between the rails and the outdoor unit. These components help limit the transmission of vibrations to the building structure.
Why the foundation is an important attachment point
The exterior siding visible in the photo consists of horizontal panels. This type of cladding should not be considered a sufficient load-bearing element for a heat pump.
The support must be fastened to a structure capable of bearing the weight of the unit and the dynamic loads generated by the compressor and fan.
In this project, the vertical support posts extend down to the foundation. This configuration makes it possible to position the equipment at an appropriate height while avoiding placing its entire load solely on the siding.
Precise coordination with the existing Fujitsu system
The presence of a second heat pump on the same wall required additional planning.
Each unit must be able to draw in and discharge air without being obstructed by the other. An outdoor unit expels a large amount of air through its front fan. If the units are too close together or poorly oriented, the discharged air can recirculate toward the heat exchanger.
This recirculation can reduce performance, particularly during periods of high demand.
We therefore paid attention to:
- the distance between the two units;
- access to the service panel;
- front clearance;
- the position of the refrigerant connections;
- cable routing;
- future maintenance of both units;
- circulation around the basement window.
The new unit was positioned to the right of the existing equipment, with its fan oriented toward a clear area. The front is not obstructed by a fence, shed, or nearby structure.
Two clearly separated electrical disconnects
The photograph shows two electrical enclosures installed between the units. This separation is important because each system must have its own accessible means of disconnecting power.
The disconnect allows a technician to de-energize the equipment before servicing it.
For a compliant and safe installation, we check in particular:
- the supply voltage;
- the circuit rating;
- the minimum required current;
- the maximum permitted protection;
- the cable type;
- grounding;
- the sealing of the outdoor connections;
- compatibility with the nameplate.
The number of zones alone does not determine the breaker size. Electrical selection must be based on the precise data for the installed outdoor model.
The proximity of the two disconnects makes them easy to identify, but the circuits must remain clearly identifiable to avoid any confusion during servicing.
Lines grouped inside an exterior line-set cover
Below the new Fujitsu AIRSTAGE unit, the connections are routed into a white line-set cover mounted horizontally on the foundation.
This channel generally protects and organizes:
- the refrigerant lines;
- their insulation;
- the communication cable;
- certain electrical connections;
- the drainage components, depending on the configuration.
Without protection, the refrigerant insulation can be damaged by ultraviolet rays, animals, gardening tools, or work carried out around the house.
The line-set cover also provides a much cleaner finish. On a wall that already contains several pieces of equipment, careful organization of the connections prevents the installation from looking improvised.
The lower passage visible in the photo
A section of piping runs down beneath the line-set cover toward the ground. It must remain protected from physical damage and monitored to ensure it is not blocked by snow, vegetation, or landscaping work.
For every project, we aim to reduce the amount of piping left exposed. However, some sections must remain accessible or follow a specific route depending on the interior layout.
The proximity of the basement window
The new unit is installed immediately to the left of a basement window. Its positioning was intended to preserve access to this opening and avoid blocking natural light.
A heat pump installed directly in front of a window can cause several problems:
- reduced natural light;
- more difficult access to the window;
- more noticeable noise indoors;
- obstruction of a functional opening;
- insufficient space for maintenance.
In this project, the fan remains offset from the window. The appliance is also installed high enough not to unnecessarily obstruct the glazed area.
We must always check the window's function. When it is an opening used for bedroom egress, additional requirements may apply. An outdoor unit must not compromise the safe use of the opening.
Managing water during defrosting
In winter, a heat pump naturally accumulates frost on its outdoor heat exchanger. The system periodically initiates a defrost cycle to melt this buildup.
The water produced falls beneath the unit. If the appliance is too close to the ground, this water can form a block of ice that gradually rises toward the chassis.
The wall bracket visible in the photo maintains clearance beneath the equipment, which facilitates drainage.
We must nevertheless take into account:
- the slope of the ground;
- the proximity of the foundation;
- the presence of the window;
- the traffic area;
- the risk of ice accumulation;
- winter maintenance.
The homeowner must keep the area clear after storms. Snow should never be pushed against the heat pump or piled up in front of its fan.
The features of a properly selected Fujitsu Aquila XLTH system
A multizone range designed for multiple indoor configurations
The Fujitsu AIRSTAGE Aquila series allows different types of indoor units to be connected to multizone outdoor units.
The manufacturer's documentation presents 18,000, 24,000, 36,000, and 45,000 BTU/h outdoor units. Depending on the model, they can accommodate two to five indoor units.
Compatible styles include:
- the wall-mounted units;
- the Slim Duct units;
- the compact cassettes;
- the Mid Static Duct units.
For a dual-zone heat pump, the 18,000 BTU/h outdoor unit can be connected to two indoor units in several approved combinations. Page 2 of the Fujitsu documentation specifically presents combinations of indoor-unit capacities ranging from 7,000 to 15,000 BTU/h for this configuration.
This does not mean that every combination is automatically suitable for every home. The tables confirm technical compatibility, but they do not replace a heat-loss calculation.
Heating suited to cold temperatures
Fujitsu’s cold-climate range can operate in heating mode down to -26 °C, depending on the applicable model.
This capacity is particularly important for an installation in Charlemagne. A heat pump used in Lanaudière must continue producing heat when the outdoor temperature drops well below freezing.
However, exact performance varies with temperature. As with any heat pump, available capacity and efficiency generally decrease as the cold becomes more intense.
The selection must therefore consider:
- the home’s heating load;
- the unit’s low-temperature capacity;
- existing supplemental heating;
- heat distribution between rooms;
- occupant habits.
We avoid presenting a minimum operating temperature as a guarantee that the unit will independently cover the building’s entire needs under all conditions.
Inverter technology and capacity modulation
The Inverter compressor adjusts its speed to match the demand from the zones.
When both indoor units require little heating or cooling, the system can operate at a reduced output. As the load increases, it gradually speeds up.
This modulation helps to:
- reduce temperature fluctuations;
- extend low-power cycles;
- limit certain abrupt starts;
- improve comfort;
- adjust consumption to actual demand.
In a dual-zone installation, this modulation capability is important because one zone can operate while the other is off or requires less power.
Independent zone operation has limitations
Each indoor unit can be controlled separately. Occupants can adjust the temperature and fan speed in each space.
However, the two indoor units share the same refrigerant circuit. They must therefore operate in the same general mode.
The system can:
- heat both zones;
- cool both zones;
- operate only one zone;
- maintain different setpoints.
It normally cannot heat one zone while the other simultaneously calls for cooling.
This feature should be explained during the selection process. It prevents occupants from assuming that “dual zone” means two completely independent systems.
Understanding the capacity for connections of up to 130%
Fujitsu documentation indicates that a multizone outdoor unit can accept connected indoor capacity of up to 130% in certain configurations.
This allows some flexibility when the indoor units do not all demand their full capacity at the same time.
However, Fujitsu clearly states that exceeding 100% does not increase the outdoor unit’s output capacity. If both zones demand high output simultaneously, the available capacity must be divided between them.
This concept is essential for properly sizing a multi-zone heat pump.
An approved combination is not necessarily the ideal combination
A combination may be technically approved by the manufacturer but poorly suited to a home’s needs.
For example, two large indoor units connected to a smaller outdoor unit may be suitable when the zones rarely reach their maximum load at the same time. The same combination could be unsuitable if both spaces constantly require their full capacity.
The choice should be based on the building’s actual use.
Factors we analyze before confirming the BTU rating
We cannot determine the appropriate capacity based solely on floor area.
We also assess:
- insulation;
- airtightness;
- orientation;
- windows;
- ceiling height;
- number of floors;
- exposed walls;
- air circulation;
- the presence of a basement;
- existing heating equipment.
Fujitsu’s documentation itself specifies that its combination tables are not intended to select system capacity. The manufacturer recommends using its design software to select H series AIRSTAGE equipment.
Commissioning is just as important as the physical installation
A heat pump can be perfectly secured to the wall and still perform poorly if commissioning is neglected.
After installation, we specifically check:
- quality of the refrigerant connections;
- system tightness;
- evacuation;
- communication between the units;
- power supply;
- operation of both zones;
- supply air temperature;
- vibrations;
- abnormal noises;
- indoor drainage;
- operating cycles.
Evacuation is particularly important. It removes air and moisture from the circuit before startup.
Moisture left in the lines can damage the compressor oil and cause long-term problems.
Mistakes to avoid when two outdoor units share the same wall
Installing the equipment too close together
Insufficient clearance can restrict airflow and make maintenance more difficult.
Block the disconnect switches
Disconnecting devices must remain accessible.
Stacking the lines without organization
Crossed routes make repairs more difficult and increase the risk of confusion.
Neglecting the basement window
The unit must not block the opening or unnecessarily reduce natural light.
Installing the unit too low
Snow and ice can obstruct the heat exchanger or drainage.
Forgetting about vibrations
Properly adapted pads and a secure fastening system help limit noise transmitted to the building.
Relying solely on the capacity listed on the indoor units
The two zones share the outdoor unit’s capacity. The total BTU rating of the indoor units does not automatically represent the power available simultaneously.
Maintenance required around the two heat pumps
The presence of two units side by side requires a well-maintained outdoor area.
We particularly recommend:
- trim the grass around the supports;
- remove leaves and debris;
- keep the fans clear;
- avoid leaning objects against the units;
- clear snow without striking the lines;
- monitor ice buildup;
- preserve access to the electrical panels.
The outdoor heat exchangers must be able to draw in air freely. Dust, pollen, or debris can reduce heat exchange.
Inside, the filters of both units in the dual-zone system should be inspected regularly. Even a less frequently used area can accumulate dust.
An installation adapted to Charlemagne’s real-world constraints
This Fujitsu Aquila XLTH dual-zone heat pump installation in Charlemagne stands out for its integration alongside an existing Fujitsu system.
We had to coordinate:
- the wall bracket;
- the clearances for both units;
- the electrical disconnects;
- the basement window;
- the line-hide cover;
- winter drainage;
- maintenance access.
The final photograph shows a neat installation, with the new elevated AIRSTAGE R32 unit, clear front clearance, and lines grouped along the foundation.
At AirGreen, we install wall-mounted heat pumps, multi-zone systems, and central equipment in Montreal, Laval, Longueuil, the North Shore, and the South Shore, including Charlemagne and neighboring municipalities in Lanaudière.
Our approach is to adapt each project to the existing building rather than impose an identical setup everywhere. Window placement, the presence of other equipment, the foundation type, and the occupants’ needs directly influence the quality of an HVAC installation.