An outdoor wall-mounted installation designed to free up ground space and protect the heat pump
In Calixa-Lavallée, in Montérégie, we installed a Fujitsu AIRSTAGE Altair 500 wall-mounted heat pump at a brick residence where the outdoor environment imposed a very practical constraint: the available space along the house was narrow, unpaved, and directly exposed to moisture, vegetation, and seasonal accumulation.
Rather than installing the outdoor unit directly on the ground, we chose a configuration on a metal wall bracket, securely fastened to the foundation. The project photograph clearly shows the benefit of this approach: the compressor is completely clear of the ground, with open space beneath the unit, while the refrigerant connections lead directly into the building behind the unit.
We also installed the outdoor electrical disconnect near the heat pump, on the foundation. The connection is accessible without encroaching on the passage around the house. The result is particularly compact: the outdoor unit, its lines, and its power supply were grouped in a precise technical area rather than spread along the façade.
The installed machine belongs to the Fujitsu AIRSTAGE Altair 500 family, a series of single-zone wall-mounted heat pumps using R-32 refrigerant and Inverter technology. The range includes models 09KPAS1, 12KPAS1, 18KPAS1, 24KPAS1, 30KPAS1, and 36KPAS1. The exact capacity of the equipment visible in this photo is not sufficiently legible on the nameplate to be stated with certainty; we therefore rely on the verified technical specifications of the series rather than arbitrarily assigning a BTU rating to the project.
Why we chose a wall-mounted installation rather than a ground installation
One of the most interesting features of this project in Calixa-Lavallée is the position of the outdoor unit.
In the photo, the ground is natural and uneven. Vegetation can also be seen in the immediate vicinity of the foundation. An installation directly at ground level would have required different preparation and would have placed the unit much closer to:
- soil;
- leaves;
- grass;
- surface water;
- accumulated snow;
- windblown debris.
The wall bracket, on the other hand, allows us to create permanent clearance beneath the heat pump.
This decision becomes particularly relevant in winter. A heat pump produces water during its defrost cycles. This water must be able to fall and drain away without becoming trapped beneath the chassis.
The additional clearance also makes future service easier. For our technicians, access to the underside and sides of the unit makes certain HVAC maintenance and diagnostic operations simpler.
A bracket that must withstand the weight, vibrations, and Quebec seasons
Installing a compressor on a wall is not simply a matter of screwing on two metal brackets.
We must take into account:
- the weight of the unit;
- the nature of the structure;
- the quality of the anchors;
- levelness;
- compressor vibrations;
- the forces exerted during operating cycles;
- prolonged exposure to outdoor conditions.
The Altair 500 range includes different outdoor unit sizes depending on capacity. According to the Fujitsu technical data sheet, the outdoor units weigh approximately 23 kg to 53 kg, or about 51 to 117 lb, depending on the model.
This weight must remain perfectly supported year after year.
In this installation, the heat pump rests on two horizontal crossbars of the bracket, which are themselves supported by triangulated arms. This geometry transfers the load to the building structure.
A very short and compact refrigerant run
The photograph also shows something we appreciate in this type of heat pump installation: the refrigerant lines enter the house directly behind the outdoor unit.
The insulated line set exits from the side of the unit and then enters the building through a sloped finish that protects the exterior passage.
This configuration reduces the amount of exposed piping.
When we can intelligently position the outdoor unit closer to the area corresponding to the indoor unit, we gain several advantages:
- less visible piping;
- fewer sections exposed to the elements;
- a more discreet exterior finish;
- fewer changes in direction;
- a simplified route when the interior layout allows it.
However, this does not mean that a short installation can be improvised. Fujitsu documentation specifies minimum piping lengths: approximately 3 m for the 9,000 to 24,000 BTU models and 5 m for the 30,000 and 36,000 BTU versions.
Even when the indoor unit is directly on the other side of the wall, we must therefore comply with the manufacturer's technical requirements.
Different copper dimensions depending on capacity
The lines visible in the photo are protected by an insulating sleeve. The actual diameters depend on the capacity of the installed Altair 500.
The Fujitsu technical specifications indicate:
- 9,000 and 12,000 BTU: 1/4 in. liquid line and 3/8 in. gas line;
- 18,000 and 24,000 BTU: 1/4 in. liquid line and 1/2 in. gas line;
- 30,000 and 36,000 BTU: 3/8 in. liquid line and 5/8 in. gas line.
This is essential information when replacing a system.
We sometimes encounter properties where an old heat pump has already been removed and the owner wants to keep the existing piping. Before doing so, we must check the diameter, length, condition of the copper, and its compatibility with the new unit.
Incorrect piping can compromise system performance even if the heat pump itself is properly sized.
An electrical disconnect installed near the unit
To the right of the heat pump, you can see the outdoor electrical disconnect mounted on the wall.
This component is an integral part of the installation.
The Fujitsu Altair 500 operates at 208 to 230 V, 60 Hz, single-phase. However, the required circuit breaker varies according to capacity:
- 15 A for the 9,000 BTU models;
- 15 A for the 12,000 BTU models;
- 15 A for the 18,000 BTU models;
- 20 A for the 24KPAS1;
- 30 A for the 30,000 and 36,000 BTU models.
This is why we always check the electrical supply before installation.
An older wall-mounted air conditioner may have used a different circuit. The presence of an existing circuit therefore does not automatically mean that it is suitable for the new Fujitsu heat pump.
Fujitsu Altair 500: performance, heating, efficiency, and points to check before purchase
A range from 9,000 to 33,000 BTU nominal cooling capacity
The Fujitsu Altair 500 is not a single unit offered in one capacity.
The range includes:
- 09KPAS1 : 9,000 BTU/h nominal cooling capacity;
- 12KPAS1 : 12,000 BTU/h;
- 18KPAS1 : 18,000 BTU/h;
- 24KPAS1 : 22,000 BTU/h;
- 30KPAS1 : 30,000 BTU/h;
- 36KPAS1 : 33,000 BTU/h.
The published nominal heating capacities are 10,000, 14,000, 18,000, 24,000, 30,000, and 34,000 BTU/h, respectively.
This distinction is important for homeowners who sometimes equate the model name with its marketed capacity.
At AirGreen, we size a wall-mounted heat pump in Calixa-Lavallée based on the building, rather than simply using a round square-footage figure.
Inverter technology enables true modulation
The Altair 500 series uses an Inverter compressor that adjusts its output according to demand.
This modulation is shown directly in the manufacturer’s specifications.
The 12,000 BTU version, for example, can modulate its cooling output approximately between 3,100 and 13,600 BTU/h. In heating mode, it operates approximately between 2,700 and 17,000 BTU/h.
The 18,000 BTU model can reach up to 24,000 BTU/h in heating, depending on conditions.
This adaptability is useful when a home does not need the system’s full output throughout the day.
In spring or fall, a heat pump can operate at a reduced output instead of continuously shutting down and restarting completely.
A SEER2 rating of up to 26
Energy performance varies by capacity. The Fujitsu specifications sheet lists the following SEER2 values:
- 26.0 for the 09KPAS1;
- 24.0 for the 12KPAS1;
- 22.0 for the 18KPAS1;
- 21.5 for the 24KPAS1;
- 22.0 for the 30KPAS1;
- 21.0 for the 36KPAS1.
Several versions in the product line also have ENERGY STAR ratings, and some models are designated ENERGY STAR Cold Climate or ENERGY STAR Most Efficient in Fujitsu documentation.
For a customer comparing several heat pumps, it is therefore more relevant to analyze the exact combination of units than to compare only the brand logos.
Rebates: the system’s exact number must be verified
When a homeowner is looking for a heat pump rebate in Quebec, eligibility must always be verified based on the exact installed combination.
A product line can include several capacities with different ratings. A model named Altair 500 is therefore not necessarily interchangeable with all other Altair 500 versions in a financial assistance program.
We recommend checking:
- the indoor unit model;
- the outdoor unit model;
- the certified combination;
- the applicable program criteria;
- the rules in effect on the project date.
This is an important precaution to avoid planning a budget based on financial assistance that would not apply to the combination actually installed.
Heating down to -15 °C within the published range
The Altair 500 series technical data sheet indicates a heating operating range of -15 °C to 24 °C.
For homes in Calixa-Lavallée and the Montérégie region, this makes it possible to use the heat pump as a heating source for a significant portion of the season.
However, precision is important: a minimum operating temperature does not mean that the unit provides its full rated capacity at that temperature, nor that it can necessarily replace all of a home’s heating on its own during the coldest periods.
We always take the building’s heat losses and the existing supplementary heating system into account.
R-32: an important feature of this generation of Altair 500
All Altair 500 models presented in the documentation use R-32. Fujitsu reports a global warming potential of 675 for this refrigerant, compared with 2,088 for R-410A in its comparison, representing an announced 68% reduction in GWP.
The use of R-32 also affects technical procedures.
The equipment, handling methods, and service practices must be adapted to the refrigerant used. For this reason, replacing an older system does not simply involve connecting the new unit to the existing installations.
A compact heat pump suited to narrow side passages
The Calixa-Lavallée installation clearly illustrates one of the advantages of a relatively compact outdoor unit.
The building has a narrow side passage. The compressor was not supposed to unnecessarily block access to the backyard.
Depending on capacity, Altair 500 outdoor units measure approximately:
- 663 mm wide for the 9,000 and 12,000 BTU versions;
- 799 mm for the 18,000 and 24,000 BTU models;
- 940 mm for the 30,000 and 36,000 BTU units.
However, the choice of location must take clearances into account, not just the physical dimensions of the cabinet.
We avoid installing a unit where its heat exchanger would be blocked or where the technician could no longer properly access the components.
Relatively quiet outdoor operation
Depending on capacity, Fujitsu publishes approximate outdoor-unit sound levels ranging from 46 to 56 dB(A), depending on the model and operating mode.
In a side passage between two properties, this factor deserves particular attention.
The distance from windows, outdoor living areas, and neighboring properties influences our choice of location.
The wall-mounted support must also be rigid and properly secured so that the building structure does not become a resonance chamber.
What the image does not show: the important steps before commissioning
Once the unit has been installed on its support, several technical steps remain necessary.
In particular, we must ensure:
Refrigerant connection integrity
Even a minor leak can eventually affect system performance.
Vacuum quality
Moisture and air in the lines must be removed according to the proper procedures before commissioning.
Wiring
The connections must meet the manufacturer’s requirements.
Drainage
The indoor unit produces condensate during cooling. It must drain continuously without flowing back toward the unit.
Complete operation
We check the startup, airflow, controls, temperatures, and the system’s overall response.
These steps are not visible in a final photo, but they represent an essential part of a professional HVAC installation.
Why this installation differs from a project on a ground slab
On several installations carried out in Montreal, Laval, Longueuil, the North Shore and the South Shore, we can use a slab or ground-mounted base when the surroundings allow it.
In Calixa-Lavallée, the visible layout of the property made the wall-mounted support particularly appealing.
This allows us to achieve:
- more clearance beneath the equipment;
- minimal use of ground space;
- a well-organized technical area;
- a very compact refrigerant connection;
- clear access to the side passage;
- an installation suited to the natural terrain.
These are precisely the decisions that change from one property to another.
A standardized installation does not always produce a good result. We prefer to adapt the support, piping route, and unit positioning to the actual building.
Mistakes to Avoid in a Similar Installation
In a narrow outdoor configuration like this one, several mistakes can have long-term consequences.
We specifically aim to avoid:
- a heat pump positioned too close to the ground;
- an insufficiently rigid wall bracket;
- insufficient clearance behind the heat exchanger;
- a unit that blocks the passage;
- refrigerant lines bent too tightly;
- damaged insulation outdoors;
- a disconnect that is difficult to access;
- piping incompatible with the model;
- poor management of defrost water;
- a location that makes heat pump maintenance difficult.
The right location therefore depends not only on where it is quickest to drill through the wall.
AirGreen in Calixa-Lavallée: Designing the Installation Around the Home
This Fujitsu AIRSTAGE Altair 500 wall-mounted heat pump project in Calixa-Lavallée illustrates an important part of our work at AirGreen: adapting the machine to the building’s physical constraints.
Here, we had a brick facade, an accessible foundation, a relatively narrow side passage, and a property that was not as naturally suited to a very low ground-level installation.
The metal wall bracket, compact connection through the foundation, and nearby electrical disconnect help keep the installation organized and accessible.
This is the same approach we use on our heat pump projects in Montreal, Laval, Longueuil, the North Shore, the South Shore, and throughout Greater Montreal: we do not consider only the machine’s performance. We also consider its real-world environment.
A Fujitsu Altair 500 can offer excellent modulation, attractive energy efficiency, R-32 refrigerant, and several capacities suited to different needs. But its long-term performance also depends on the quality of its installation: support, electrical supply, piping, drainage, location, and commissioning.
In Calixa-Lavallée, this elevated installation allows these elements to be brought together in a compact, practical configuration suited to the property’s outdoor conditions.