An installation adapted to a restricted space, with a raised outdoor unit and preserved technical access
In Saint-Jean-Baptiste, we completed this installation of a Fujitsu AIRSTAGE Altair 500 wall-mounted heat pump in an outdoor configuration that required careful space management. The outdoor unit was placed on a raised metal ground support, between a railing and a brick wall, in front of a concrete block surface.
The photo clearly shows the site's constraints: limited passage on the left, a masonry wall at the back, conduits and electrical boxes on the right, and a relatively compact circulation area. In this type of situation, we aim to preserve three essential elements: sufficient clearance for air circulation, a stable installation, and reasonable access for HVAC maintenance.
Choosing a raised ground support is particularly relevant here. The unit does not rest directly on the concrete slab. Instead, it is installed on a rigid four-legged structure that is itself securely anchored to the ground. This keeps the heat pump above the water, snow, and ice that can accumulate during Quebec winters.
Why this raised support is particularly useful in Saint-Jean-Baptiste
In several projects on the South Shore, we have to work with narrow outdoor spaces, balconies, stairs, foundation walls, and surfaces already occupied by other equipment.
Here, using a raised metal support provides several practical benefits:
- The heat pump remains a safe distance from the ground;
- The unit's base is less exposed to snow accumulation;
- Water can flow beneath the structure without directly surrounding the unit;
- Maintenance beneath the unit is simpler;
- The condenser's front remains completely unobstructed;
- The system is stabilized on an independent, robust structure.
Vibration isolation pads can also be seen beneath the outdoor unit. Their presence helps reduce the direct transmission of vibrations between the compressor and the metal structure.
This detail is important, especially when the unit is installed near a wall, patio, or occupied area.
The R-32 Fujitsu AIRSTAGE Altair 500: a wall-mounted heat pump designed for heating and cooling
The Fujitsu Altair 500 is part of the single-zone H AIRSTAGE series. The lineup includes several capacities, including models 09KPAS1, 12KPAS1, 18KPAS1, 24KPAS1, 30KPAS1, and 36KPAS1.
The exact capacity of the unit installed for this project cannot be read reliably enough from the photo. We therefore avoid assigning it a precise BTU rating without confirmation from the nameplate.
R-32 refrigerant clearly identified on the unit
The marking R32 is visible on the Fujitsu outdoor unit installed in Saint-Jean-Baptiste.
According to the Altair 500 series documentation, R-32 has a global warming potential of 675, compared with 2,088 for R-410A. Fujitsu indicates a 68% reduction in GWP compared with R-410A.
The documentation also specifies that R-32 models require less refrigerant while maintaining the desired heating performance.
However, when replacing an old wall-mounted heat pump, the requirements specific to the new refrigerant must be met, and the entire installation must be confirmed as compatible.
Inverter technology for more precise modulation
The Altair 500 series uses an Inverter compressor. Unlike a system that operates only at full capacity before shutting down completely, the Inverter can adjust its capacity according to the building’s needs.
This modulation notably helps to:
- maintain a more stable temperature;
- reduce comfort fluctuations;
- adjust consumption to the actual load;
- limit certain on-off cycles;
- make operation quieter at low demand.
This feature is particularly useful during the transitional periods of spring and fall, when heating or cooling demand varies significantly throughout the day.
Heating down to -15 °C according to the published operating range
The Fujitsu technical data sheet indicates an operating range in heating mode of -15 °C to 24 °C for Altair 500 series models.
This information must be understood correctly. The fact that a heat pump can operate at -15 °C does not mean that it retains exactly its rated capacity at that temperature. As with any heat pump, performance varies according to outdoor conditions.
For a property in Saint-Jean-Baptiste, the system choice must therefore take into account the home’s heating strategy, insulation, heat losses, and available supplementary heating.
Different efficiencies depending on the selected capacity
Fujitsu’s documentation lists the following TRÈS2 values:
- 26.0 for the 9,000 BTU model;
- 24.0 for the 12,000 BTU model;
- 22.0 for the 18,000 BTU model;
- 21.5 for the 24,000 BTU model;
- 22.0 for the 30,000 BTU model;
- 21.0 for the 36,000 BTU model.
This clearly shows that the specific installed combination must be evaluated rather than generalizing the performance of the entire range.
ENERGY STAR ratings also vary by model.
Indoor operation that can be very quiet
Fujitsu indicates a minimum indoor sound level of 19 dB(A) in quiet mode for the 9,000 and 12,000 BTU versions. Higher capacities have different minimum levels, including 26, 31, and 32 dB(A).
The series also offers six fan speeds plus automatic mode.
This flexibility is useful when an indoor unit is installed in a living room, bedroom, or open-plan area where perceived noise is part of overall comfort.
ProCore coils and Hydro Fin fins
Fujitsu’s documentation also presents ProCore copper coils, designed to offer better corrosion resistance. The Hydro Fin finned heat exchanger also helps improve the system’s durability.
These elements are important in an environment like Quebec, where outdoor equipment is exposed to significant temperature fluctuations, humidity, snow, and repeated freeze-thaw cycles.
A compact installation despite several elements around the unit
The Saint-Jean-Baptiste project clearly shows that a successful installation depends on more than just the heat pump itself.
To the right of the unit, several ducts and an electrical box are visible. On the left, a railing limits the available space. The rear wall is made of concrete blocks, while the adjacent wall is brick.
We therefore positioned the unit to:
- keep the fan grille clear;
- avoid wedging the unit against the walls;
- keep access to the service side;
- protect the connections;
- maintain adequate clearance from the ground;
- limit encroachment into the passageway.
This approach is important for installations of wall-mounted heat pumps in Montreal, Laval, Longueuil, the North Shore, and the South Shore, where properties may offer very little available space for the outdoor unit.
Good airflow in front of the condenser
The Fujitsu outdoor fan occupies a large portion of the front of the unit. Therefore, an obstacle should not be placed directly in front of it.
On this installation, the front area remains open. The railing on the left does not directly obstruct the fan grille, and the space in front remains clear.
This allows the system to move air properly through the heat exchanger.
Poor airflow around an outdoor unit can reduce performance, increase compressor strain, and make the system less efficient.
Piping dimensions vary by model
The Altair 500 series uses several refrigerant pipe sizes.
According to Fujitsu:
- 9,000 and 12,000 BTU: 1/4 in. liquid and 3/8 in. gas;
- 18,000 and 24,000 BTU: 1/4 in. liquid and 1/2 in. gas;
- 30,000 and 36,000 BTU: 3/8 in. liquid and 5/8 in. gas.
This information is particularly important when replacing a system.
We sometimes encounter installations where homeowners wish to automatically reuse the existing lines to reduce the amount of work. This may be possible in some cases, but only if the size, condition, and compatibility truly meet the requirements of the new system.
Different line lengths depending on capacity
Fujitsu also indicates maximum piping lengths of up to:
- 20 m for the 9,000 and 12,000 BTU models;
- 30 m for the 18,000 and 24,000 BTU models;
- 50 m for the 30,000 and 36,000 BTU models.
The maximum vertical difference can reach 15, 25, or 30 m, depending on the capacity.
This offers valuable flexibility in homes where the indoor and outdoor units cannot be installed directly on opposite sides of the same wall.
The electrical supply must match the selected model
All versions listed in the Fujitsu specifications operate at 208–230 V, 60 Hz, single-phase.
However, the circuit breaker requirements are different:
- 15 A for the 9,000, 12,000, and 18,000 BTU models;
- 20 A for the 24,000 BTU;
- 30 A for the 30,000 and 36,000 BTU versions.
The project photo also shows the electrical connection positioned near the unit. The goal of a professional HVAC installation is to coordinate the refrigeration, mechanical, and electrical work so that everything is coherent and easy to maintain.
Why future access is just as important as the initial installation
When we install a heat pump, we also think about the technician who may eventually need to return.
A unit wedged between two obstacles can become difficult to clean or repair. An inaccessible panel can turn a simple service call into a much more complex job.
In this Saint-Jean-Baptiste installation, despite the limited space, the front remains completely accessible and the sides retain sufficient clearance to allow the necessary technical work.
The mistakes we avoid with this type of installation
For a wall-mounted heat pump, several installation errors can reduce the quality of the result:
- installing the unit directly at ground level;
- leaving too little space in front of the fan;
- installing the compressor in an enclosed corner;
- placing the unit where snow can easily cover it;
- using refrigerant lines of the wrong diameter;
- neglecting the condensate drain;
- making the service panel inaccessible;
- fastening the support to an insufficiently stable surface;
- leaving cables and pipes unorganized.
The Saint-Jean-Baptiste project demonstrates a particularly interesting solution when wall mounting is not desirable or when the building’s configuration favors a freestanding support.
The raised ground support: an alternative to the wall-mounted support
We use different types of supports depending on the building.
A wall-mounted support can be an excellent choice when the foundation is suitable for anchoring and when we want to completely clear the ground. But in some situations, a raised freestanding support is a better solution.
In this case, the structure rests directly on the slab. All four feet are secured to the ground, and the heat pump is positioned above the structure.
This choice avoids adding a load to the concrete-block wall while keeping the unit at an appropriate height.
A solution particularly well suited to urban and semi-urban spaces
Although Saint-Jean-Baptiste has a different residential layout than denser areas of Montreal, we often encounter the same constraints: narrow façades, stairs, balconies, fences, side passages, and existing electrical equipment.
Our experience with installations in Montreal, Laval, Longueuil, on the North Shore and the South Shore allows us to adapt the support and line routing rather than use the same method everywhere.
This flexibility is essential in HVAC.
Sizing remains the first technical decision
The Altair 500 series covers several important capacities, but the choice should never be based solely on the size of the home.
We consider, among other factors:
- heat losses;
- insulation;
- fenestration;
- orientation;
- the number of floors;
- open or partitioned areas;
- the natural movement of air;
- the existing heating system;
- the homeowner's expectations.
An oversized heat pump may operate in shorter cycles than ideally desired, while an undersized unit may run continuously during periods of high demand.
An AirGreen installation designed to go beyond startup
This Fujitsu AIRSTAGE Altair 500 installation in Saint-Jean-Baptiste is interesting because it demonstrates a solution that differs from conventional wall-mounted installations.
Here, the choice of an elevated, independent support addresses the site's actual constraints. The unit remains stable, accessible, clear of obstructions, and positioned above the slab.
That is exactly what we strive for at AirGreen: an installation that works properly today, but that still makes sense several years later when HVAC maintenance, cleaning, or repairs become necessary.
The heat pump itself is important. But the support, clearance, routing of the lines, electrical connection, and accessibility have an equally important impact on the final quality of the project.