A precise installation in a confined indoor space, above an opening and near a wall corner
In Bois-des-Filions, on the North Shore, we installed a Fujitsu Aquila XLTH dual-zone heat pump to heat and cool two distinct areas of the property using a single outdoor unit. The project presented a very practical constraint: one of the indoor units had to be integrated into an area where available wall space was limited by an opening, a corner, an adjacent window, and an existing curtain rod.
The photograph shows a Fujitsu AIRSTAGE wall-mounted unit installed above a passageway, near the ceiling. This choice preserves usable wall space and distributes air from a high point without encroaching on the circulation area. In a room where every section of wall matters, it is not enough to choose a location that appears open. It is also necessary to confirm that the unit will be able to draw in enough air, open its front panel, project airflow without obstruction, and remain accessible for filter cleaning.
This project clearly illustrates our approach to an HVAC installation: we adapt the positioning to the building’s actual constraints without overlooking the manufacturer’s technical requirements or future maintenance needs.
Why was a dual-zone heat pump the right choice?
A single-zone heat pump works well when one indoor unit can distribute air effectively throughout the entire intended space. In a home divided into several areas, this distribution is often insufficient.
Doors, corridors, stairwells, and changes in elevation limit the natural movement of air. A unit installed in the living room may maintain the temperature of an open-concept area perfectly while leaving a distant bedroom too hot in summer or too cold in winter.
The dual-zone configuration selected in Bois-des-Filions makes it possible to connect two indoor units to a single Fujitsu outdoor unit. Each unit directly serves its own area, improving comfort precision and reducing reliance on air circulation between rooms.
This solution is particularly suitable for properties comprising:
- a ground floor and an upper floor;
- a living area and a bedroom;
- a main room and a basement;
- an original section and an addition;
- two spaces used at different times;
- rooms with opposite sun exposures.
The homeowner can adjust each unit according to how its area is used. A rarely occupied room can be maintained at a more moderate temperature, while the main living space receives more heating or cooling.
Two independent controls, with a compatible overall mode
Each indoor unit in a Fujitsu multi-zone system can be controlled separately. The set temperature, fan speed, and airflow direction can be adjusted according to the needs of each area.
However, there is an important rule: units connected to the same compressor must operate in compatible modes. The system can heat or cool, but it cannot provide heating in one zone and cooling in the other simultaneously.
Fujitsu documentation clearly states that AIRSTAGE multi-zone systems provide heating and cooling, but not both modes at the same time.
In a residence, this limitation is generally easy to manage. During the winter, both areas usually require heating. During the summer, they require cooling. Nevertheless, we explain this operation to the homeowner during commissioning to avoid conflicting commands between the two units.
A wall-mounted unit installed above an opening
The most visible element of this installation is the positioning of the indoor unit above an opening.
This type of location can be advantageous when properly planned. It allows you:
- to use a section of wall that would otherwise be difficult to arrange;
- to preserve space for furniture;
- to distribute air from a central or unobstructed point;
- to minimize the unit’s visual impact;
- to position the wall-mounted head closer to the piping route.
However, several details must be checked before mounting.
The distance from the ceiling
A wall-mounted unit generally draws air in through its upper section. Insufficient space above the unit can restrict airflow and make it difficult to open the front panel.
In the photograph, the unit is positioned near the ceiling, reflecting the limited height available above the opening. In this type of situation, we must measure the usable clearance precisely and confirm that it remains compatible with the selected model.
Even when a unit can physically fit in the space, that does not automatically mean its installation will be functional there. Access to the filters and service fasteners is part of the assessment.
The proximity of the wall corner
The right side of the unit is near a wall return. This proximity requires precise alignment so that the casing does not touch the trim, rod, or adjacent elements.
We must also allow access to the side containing certain internal components and connections, depending on the model configuration. A unit placed directly against an obstacle can complicate future service.
The presence of the rod
A metal rod is visible near the unit. This existing element had to be taken into account so that it would not block the panel from opening or interfere with the movement of the airflow louver.
A window accessory, thick curtain, or improperly positioned rod can disrupt airflow or make maintenance more difficult. We therefore check the space actually being used, not just the wall when it is unobstructed.
The importance of air distribution
A wall-mounted heat pump does not heat or cool only the air directly beneath it. Its effectiveness depends on its ability to project air into the room and create consistent circulation.
The unit visible in the photo is installed at a height that allows the airflow to spread above the occupied area.
In cooling mode, cold air naturally descends. A more horizontal airflow helps distribute it before it falls.
In heating mode, warm air rises. The louver can then be angled farther downward to direct heat toward the occupied part of the room.
The louver setting is therefore important. Even a properly sized unit may seem less comfortable if its airflow is directed straight at a person, door, or obstacle.
Fujitsu Aquila XLTH: a solution suited to North Shore winters
The Fujitsu Aquila XLTH range is intended for applications where cold-weather heating performance is an important criterion.
Fujitsu documentation for the H Aquila and Aquila CTEB series indicates heating operation down to -26 °C for models designed for cold climates.
In Bois-des-Filions, this capacity is relevant, since winter temperatures can fall well below freezing.
However, it is important to understand that the minimum operating temperature is not the only factor to consider. The capacity actually available decreases or varies depending on the outdoor temperature and the demand from both zones.
Our selection takes into account:
- the area of each zone;
- level of insulation;
- type of windows;
- ceiling height;
- wind exposure;
- air infiltration;
- solar orientation;
- the capacity of the existing heating system;
- the simultaneous operation of the two zones.
An approximate calculation based solely on square footage can produce an incorrect result. Two rooms of similar dimensions may have very different loads if one has several windows and the other does not.
Multi-zone configurations from 18,000 to 45,000 BTU/h
The Fujitsu range presented in the documentation includes outdoor units rated at 18,000, 24,000, 36,000, and 45,000 BTU/h.
Depending on the model, the system can power from two to five indoor units. For a dual-zone installation, several capacity combinations are permitted.
The documentation indicates, among other things, that the outdoor unit designed for two zones can be paired with different wall-mounted units with various rated capacities.
However, it is essential not to confuse the sum of the indoor units’ capacities with the compressor’s actual capacity.
Some authorized combinations exceed 100% of the outdoor unit’s rated capacity. Fujitsu specifies that this excess does not increase the system’s production capacity.
This means that an outdoor unit does not automatically produce the total capacity listed on the two wall-mounted units when both are operating at maximum simultaneously. The available capacity must then be distributed among the zones.
For this reason, Fujitsu recommends using its Design Simulator software to select H Series AIRSTAGE equipment. Combination tables confirm that an assembly is authorized, but they do not replace load analysis.
The technical steps behind a discreet interior finish
Choosing the piping route before mounting
A wall-mounted unit requires a passage for the refrigerant lines, wiring, and condensate drain.
When the unit is installed above an opening, we must take the wall structure into account. Headers, studs, cables, and finishing elements may limit the drilling location.
Before installing the mounting plate, we check:
- the wall structure;
- the likely position of the studs;
- the route to the outside;
- the slope required for the drain;
- the distance from the trim;
- future access to the unit;
- protection of the interior finish.
A poorly positioned hole may require creating a longer route or using a condensate pump that could have been avoided.
Maintaining reliable drainage
In air conditioning, the indoor unit removes moisture from the air. This water must drain through the drain line without flowing back toward the pan.
An installation located above an opening requires particular attention, since a leak could affect the wall finish, the frame, or the passage area below.
We check:
- the pipe slope;
- the absence of kinks;
- the stability of the connections;
- drainage to the outlet;
- the tank’s watertightness;
- operation during testing.
Even a slight reverse slope can cause water to accumulate, leading to odors or overflow.
Prepare the refrigeration connections
Each indoor unit of a dual-zone heat pump has its own set of lines.
The connections must be prepared precisely to prevent leaks. After assembly, we perform the necessary testing and evacuation procedures before commissioning.
Evacuation removes air and moisture from the circuit. This step is essential for compressor durability and stable operation.
Do not mix up the zones
On a dual-zone system, the refrigeration lines and wiring for each unit must be connected to the correct port on the outdoor unit.
A mix-up can cause communication problems or inconsistent operation.
We therefore identify the two zones during the work, then test them separately:
- starting the first unit;
- confirmation of the corresponding circuit;
- checking the second unit;
- heating test;
- cooling test;
- simultaneous operation;
- drainage check.
The refrigerant and A2L requirements
New generations of equipment use refrigerants whose classification may require adapted work practices.
Although the owner does not need to work on the circuit, it is important not to drill into the casing, move the lines, or disconnect the connections.
All refrigeration work must be performed with the appropriate tools, training, and procedures.
Mistakes to avoid in a compact location
The photograph of this project shows an installation integrated into a very precise space. In this type of configuration, several mistakes can compromise the result:
- install the unit without sufficient overhead clearance;
- block the front panel opening;
- place the rod too close to the louver;
- neglect the drain route;
- direct the air straight into an opening;
- choose a unit that is too wide for the space;
- secure the mounting plate without checking the structure;
- leave the lines visible without finishing;
- install the unit in a place that is impossible to clean;
- forget the capacity shared between the two zones.
We always seek to balance three objectives: performance, appearance, and accessibility.
Fujitsu indoor unit maintenance
The owner can directly contribute to the system’s performance by cleaning the filters regularly.
The filters are located behind the front panel. Access to them must therefore remain unobstructed even after adding curtains or decorative elements.
We recommend:
- a monthly inspection during periods of intensive use;
- cleaning with a soft vacuum cleaner or water;
- complete drying before putting them back in place;
- the absence of harsh products;
- a professional inspection when the heat exchanger or blower wheel is dirty.
A clogged filter reduces airflow and increases the time required to reach the desired temperature.
The owner should also monitor:
- water droplets;
- unusual odors;
- new noises;
- error codes;
- abnormal temperature fluctuations;
- the reduction in airflow.
Winter operation and defrost cycles
In heating mode, the heat pump extracts heat from the outdoor air. Frost may then form on the outdoor unit.
The system periodically performs a defrost cycle. During this cycle, the indoor unit may temporarily reduce or stop blowing air.
This behavior is generally normal. The owner may also notice a change in sound or steam around the outdoor unit.
A significant accumulation of ice that does not disappear, however, should be checked.
Subsidies: verify the complete combination
Subsidy eligibility depends on the outdoor model, the indoor units, and the installed combination.
It is not enough for the unit to bear the Fujitsu brand or the XLTH designation.
The following must be confirmed:
- the exact outdoor unit number;
- the model of each of the two indoor units;
- the recognized combination;
- the applicable performance reference;
- the installation date;
- the rules of the program in effect.
The interior photograph does not make it possible to confirm the exact capacity or a complete reference. Therefore, we cannot assign a precise subsidy amount based solely on the image.
The result of the installation in Bois-des-Filions
This Fujitsu Aquila XLTH dual-zone heat pump installation in Bois-des-Filions now allows the owner to manage two areas with greater precision.
The project stands out for:
- the use of a single outdoor compressor;
- two separately controlled zones;
- an indoor unit integrated above an opening;
- efficient use of limited wall space;
- air distribution from an elevated point;
- a system designed for cold-climate heating;
- an installation planned with future maintenance in mind.
At AirGreen, we install wall-mounted and multi-zone heat pumps in Bois-des-Filions, on the North Shore, as well as in Montreal, Laval, Longueuil, and on the South Shore.
Every project is different. Some properties offer large unobstructed walls; others require installation near a window, above a door, in a corridor, on a balcony, or beneath a structure.
Our role is to transform these constraints into a functional, clean, and durable installation, without losing sight of sizing, drainage, airflow, and service access.