Installation of a Fujitsu AIRSTAGE Aquila XLTH dual-zone heat pump in L’Île-Bizard–Sainte-Geneviève, Montreal

A precisely installed multi-zone solution in a residential side passage

This installation in L’Île-Bizard–Sainte-Geneviève perfectly illustrates the type of project in which the quality of the work depends as much on choosing the right dual-zone heat pump as on how the outdoor unit is integrated into the building. The owner wanted better temperature control in two separate spaces without adding multiple outdoor units around the residence.

We therefore installed a Fujitsu AIRSTAGE Aquila XLTH heat pump, configured to serve two zones. A single outdoor unit can therefore provide heating and cooling for two rooms or areas of the house, each controlled by its own indoor unit and remote control.

The photograph taken during our work shows several important features of this installation:

• the outdoor unit is positioned in a relatively narrow side passage;
• the exterior cladding of the house is vinyl;
• the heat pump rests on a rigid structure located above ground level;
• anti-vibration mounts are visible beneath all four support points;
• the proximity of a basement window and the foundation was taken into consideration;
• the clearance in front of the fan remains unobstructed;
• the unit uses R32 refrigerant, clearly indicated on the front panel;
• The unit was installed in a way that preserves access to the service panel.

The gloves and documents temporarily placed on the unit show that the photo was taken during the final stage of the installation, before the worksite was fully cleaned and the system was handed over to the customer.

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

In a house, two rooms of similar size may have very different heating and cooling needs. A room with many windows, exposed to afternoon sun, may accumulate a great deal of heat in summer. A bedroom located in another part of the building, on the other hand, may maintain a more stable temperature and require less air conditioning.

In winter, the situation can be reversed. A room located above a less-heated space, near an exterior wall, or exposed to prevailing winds may lose more heat than a central room.

With a Fujitsu dual-zone heat pump, each space has its own air-distribution point and setpoint temperature. For example, occupants can keep a bedroom at a lower temperature overnight while maintaining more warmth in a living area.

This zoning offers several advantages:

• a temperature better suited to how each room is used;
• less reliance on the natural movement of air between spaces;
• a single outdoor unit for two indoor units;
• a more discreet outdoor installation;
• power modulation according to actual demand;
• a reduced need to operate all zones at the same intensity.

According to Fujitsu documentation, H-series AIRSTAGE multi-zone systems can power several types of indoor units, including wall-mounted units, slim duct units, compact cassettes, and certain ducted units. Each indoor unit can be controlled independently, although the system as a whole operates in heating or cooling mode, not both modes simultaneously.

Choosing the outdoor location: a determining factor

The outdoor unit’s placement should never be decided solely based on where it seems to fit. In this project in L’Île-Bizard–Sainte-Geneviève, we had to work with a space between the house wall and the paved walkway.

The heat pump is located near the foundation, below the main level of the exterior cladding and near a basement opening. We maintained sufficient clearance in front of the fan so that air could be expelled without immediately encountering a wall, fence, or other obstacle.

Insufficient clearance in front of the unit can result in:

• recirculation of discharged air;
• reduced performance;
• increased pressure on the fan;
• more noise;
• faster accumulation of snow or debris;
• difficult access for HVAC maintenance.

The side containing the connections and technical panel must also remain accessible. During a future service call, the technician must be able to check the pressures, inspect the electrical connections, check the refrigerant connections, and access the internal components without having to move the equipment.

An installation on anti-vibration supports

The photo shows anti-vibration pads installed beneath the outdoor unit. These components are placed between the heat pump base and its support structure to limit vibration transmission.

This precaution is particularly important when the unit is installed near an exterior wall, a basement window, or an occupied room. Even a modern, well-designed appliance generates slight vibration from the compressor and fan.

An installation without adequate insulation can transmit this vibration:

• to the foundation;
• to the exterior cladding;
• to wooden structures;
• to the refrigeration lines;
• inside the house.

We also check that the unit is perfectly stable. All four support points must support the heat pump evenly. A unit that is tilted or placed on an unstable surface may produce additional vibrations and complicate water drainage during defrost cycles.

Ground and defrost water management

The side passage visible in the photo consists of gravel and concrete slabs. This configuration requires particular attention to water management.

In heating mode, the outdoor heat exchanger becomes cold and may accumulate frost. The heat pump then periodically initiates a defrost cycle. The resulting water must be able to drain beneath the unit without forming a mass of ice that could rise toward the chassis.

Poor ground preparation can result in:

• water accumulating beneath the heat pump;
• the formation of a sheet of ice;
• gradual shifting of the base;
• obstruction of the lower openings;
• premature deterioration of certain components;
• a slipping hazard in the passageway.

In this project, the unit is kept above the ground using rigid supports and anti-vibration blocks. This elevation creates useful space beneath the appliance and reduces direct contact with moisture, leaves, and small debris.

R32 refrigerant and appropriate installation practices

The label visible on the front confirms that this Fujitsu heat pump operates with R32This refrigerant is used in several newer appliances because of its thermodynamic performance and lower global warming potential than R410A.

However, R32 has characteristics that require installation using the appropriate tools and methods. In particular, we must comply with the requirements related to:

• to refrigeration fittings;
• to pressure testing;
• to leak detection;
• to pulling a vacuum;
• to refrigerant recovery;
• to workspace ventilation;
• to circuit protection.

Pulling a vacuum is an essential step. It is not enough to run a pump for a few minutes. We must remove the air and moisture present in the lines before opening the service valves. Residual moisture can react with the compressor oil, impair system operation, and reduce its lifespan.

An upgrade that protects long-term operation

The photographed unit is installed horizontally and stably. This leveling may seem simple, but it has direct consequences for operation.

An improperly leveled heat pump can:

• vibrate more;
• produce irregular noises;
• drain defrost water less effectively;
• place an uneven load on its support points;
• gradually shift the lines and connections;
• complicate future maintenance.

Before commissioning, we therefore check the level in several directions and confirm that the base cannot tip under the effect of the weight, vibrations, or freeze-thaw cycles.

The Fujitsu Aquila XLTH for personalized comfort

A multizone range suited to different configurations

Fujitsu documentation lists Aquila outdoor units rated at 18,000, 24,000, 36,000, and 45,000 BTU/h that can be connected to two, three, four, or five indoor units, depending on the model selected and the permitted combinations. The outdoor unit designed for two zones can accommodate several indoor-unit combinations, including 7,000 + 7,000 BTU, 9,000 + 9,000 BTU, 9,000 + 12,000 BTU, or 12,000 + 12,000 BTU, according to the manufacturer’s technical tables.

The exact capacity installed at this site cannot be read with sufficient precision from the photograph. We therefore do not infer it from the appearance of the unit alone. The precise model, the capacities of the indoor units, and the selected combination must always be confirmed using the nameplates and project documents.

This rigor helps avoid a common mistake: assuming a heat pump’s capacity based on the physical size of its cabinet. Several models use very similar chassis despite having different capacities and performance levels.

Sizing involves more than simply adding the BTUs

In a dual-zone configuration, it is tempting to simply add the nominal capacity of the two indoor units. This method is incomplete.

Sizing must take into account:

• of the building’s heat loss;
• of the wall and attic insulation;
• of the quality of the doors and windows;
• of solar exposure;
• of the actual area of each zone;
• of the ceiling height;
• of how frequently the rooms are used;
• of the line-set length;
• of the available capacity at low temperatures;
• of the simultaneous operation of both zones.

Fujitsu indicates in its tables that certain combinations may exceed 100% of the nominal connection capacity. However, the manufacturer specifies that this excess does not increase the outdoor unit’s total heating or cooling capacity. The available capacity is distributed among the indoor units according to demand.

An approved combination is therefore not automatically an ideal selection for every residence. The manufacturer recommends using its selection software to validate the system's actual capacity under the project's conditions.

Heating in cold weather

The Aquila versions designed for cold climates are suited to Quebec winters. The H-series documentation indicates that CTEB units can continue operating in heating mode down to -26 °C. It also mentions the use of an inverter compressor, which modulates its operation according to the required load.

It is important to understand that a minimum operating temperature does not necessarily correspond to a constant maximum capacity. As with all heat pumps, heating capacity varies according to the outdoor temperature.

We therefore analyze the capacity produced at low temperatures rather than looking only at the nominal BTU rating indicated in the system name.

Depending on the building's needs, the heat pump can work with:

• electric baseboards;
• an existing heating system;
• convector heaters;
• another backup heat source;
• a control strategy suited to periods of extreme cold.

Two independent zones, but one shared mode

Each indoor unit can have its own setpoint temperature. One zone can therefore request 21 °C while the other is set to 19 °C. The compressor adjusts its output and distributes capacity according to demand.

However, both zones must operate in the same general mode. In practice:

• both can provide heating;
• both can provide cooling;
• one zone can be turned off while the other is operating;
• they cannot provide heating and cooling simultaneously.

We explain this operation to the owner when handing over the system. This step reduces service calls caused by conflicting settings on the remote controls.

Mistakes to avoid when installing a multi-zone system

Pairing the wrong cable with the wrong refrigerant circuit

Each indoor unit must correspond to the correct line set and communication connection. Reversing them can cause inconsistent responses: the control for one room activates the circuit associated with another unit.

We identify the circuits during installation and test each zone separately before commissioning the system.

Damaging the exterior siding

The vinyl siding visible on this residence must be handled with care. Wall outlets, fixtures, and finish caps must be installed without crushing the siding or preventing its natural movement with temperature changes.

Placing the unit too close to the wall

The back of the heat pump must be able to draw in enough air. Insufficient clearance reduces airflow through the heat exchanger and may decrease performance.

Forgetting about future maintenance

A successful HVAC installation must be serviceable. We plan access to the electrical panel, service valves, heat exchanger, and removal screws.

Leaving the lines unprotected

The refrigerant lines and outdoor wiring must be protected from ultraviolet rays, moisture, impacts, and animals. A properly installed exterior finish protects the system and improves the building’s overall appearance.

Our Commissioning Procedure

Before handing over a Fujitsu dual-zone heat pump to the owner, we perform several checks:

1. checking the stability and level of the outdoor unit;
2. inspecting the vibration-isolating supports;
3. checking the clearance around the heat exchanger and fan;
4. leak testing of the refrigerant lines;
5. a measured vacuum pull-down;
6. validating the electrical connections;
7. pairing each indoor unit with its circuit;
8. testing each zone in cooling mode;
9. testing each zone in heating mode;
10. checking the condensate drains;
11. checking supply-air temperatures;
12. explanation of the remote controls and operating modes.

We also remind the customer to keep the outdoor area clean. Leaves, grass, and visible debris around the passage should be removed periodically so they do not obstruct the base or the heat exchanger.

An Installation Designed for L’Île-Bizard–Sainte-Geneviève

The properties of L’Île-Bizard–Sainte-Geneviève feature a variety of layouts: detached homes, more spacious lots, side passages, finished basements, and buildings constructed during different periods. These characteristics make an on-site assessment particularly important.

In this project, we integrated a Fujitsu outdoor unit into a limited space while maintaining:

• functional clearance in front of the fan;
• a stable base;
• protection against vibrations;
• access to the service panel;
• adequate separation from the ground;
• an installation adapted to the exterior siding.

The result is a Fujitsu Aquila XLTH dual-zone heat pump capable of providing customized comfort in two areas of the home with a single, well-integrated outdoor unit.

At AirGreen, we carry out this type of heat pump installation in Montreal, Laval, Longueuil, the North Shore and the South Shore. Each project is planned according to the building’s actual needs, the available space, the capacities authorized by the manufacturer, and the operating conditions specific to Quebec’s climate.