A meticulous indoor installation in a confined space between the window, ceiling, and masonry
In Franklin, in Montérégie, this Fujitsu AIRSTAGE Altair 700 wall-mounted heat pump installation required us to work with an interior layout where every centimeter mattered. The project photo perfectly illustrates the type of situation we regularly encounter in Quebec homes: a horizontal window occupies a large portion of the wall, the ceiling limits the available height, and an imposing brick masonry structure is immediately to the right.
Our goal was therefore not simply to find an empty wall. We had to determine a location that would allow the indoor unit to operate properly, distribute air efficiently throughout the room, and maintain a clean visual integration without compromising access to the window or the existing masonry.
The result is particularly interesting: the Fujitsu AIRSTAGE unit is installed directly above the window, centered within the available space, with controlled clearance below the ceiling. The heat pump’s white front panel blends naturally into the light-colored wall, while its proximity to the brick creates a contrast that makes the installation highly visible without making it look randomly added.
Why this location required careful HVAC planning
In a room like this, several constraints overlap.
The window considerably reduces the wall space available for a wall-mounted heat pump. On the right, the brick structure also limits the possibilities for lateral repositioning. Finally, the unit must remain far enough from the ceiling to allow proper airflow through its upper intake and to meet the clearances required for its operation and maintenance.
We therefore had to consider all of the following simultaneously:
- the width of the indoor unit;
- the available height between the window and the ceiling;
- the presence of the brick wall on the right;
- the refrigerant piping route;
- condensate drain flow;
- airflow direction;
- easy access for future HVAC maintenance;
- the visual appearance once the work is complete.
This is precisely the kind of installation where field experience makes a difference. A heat pump can be technically excellent, but poor placement can reduce the comfort it is supposed to provide.
A unit above the window: it's not just an aesthetic consideration
Positioning the unit above this window makes use of a section of wall that would otherwise be difficult to utilize.
But this choice also has a functional benefit. Installed high on the wall, the unit can project air across the room rather than directly toward the floor. With a wall-mounted heat pump, airflow direction has a major influence on comfort.
The Fujitsu Altair 700 has automatic vertical airflow direction, while the horizontal direction can be adjusted manually according to the manufacturer's specifications.
We always seek to use this airflow capacity logically. The goal is not merely to bring the internal thermostat to the set temperature, but to create as uniform a temperature as possible in the area actually being occupied.
The proximity of the masonry: a detail that must be taken seriously
The photo also shows a brick structure immediately to the right of the unit.
Masonry requires additional consideration because it can influence how we route the lines and where we can drill. We never treat a wall as a uniform surface without checking what is behind or around it.
In this Franklin installation, keeping the unit on the finished portion of the wall, rather than unnecessarily encroaching on the brick structure, results in a much more cohesive installation.
We must also anticipate how a technician will be able to open the front panel, remove the filters, and access the components during future cleaning or diagnostics.
Fujitsu AIRSTAGE Altair 700: two capacities on the same platform
The technical documentation for the Altair 700 series covers two single-zone systems:
- ASUH09KMAS / AOUH09KMAS1, with a rated cooling capacity of 9,000 BTU/h;
- ASUH12KMAS / AOUH12KMAS1, with a rated cooling capacity of 12,000 BTU/h.
The indoor photo clearly identifies the Fujitsu AIRSTAGE family, but it does not show the nameplate in sufficient detail to distinguish with certainty between the 9,000 BTU and 12,000 BTU versions. We therefore prefer to preserve this distinction rather than artificially assign a capacity to the project.
This detail is important: in our field, proper heat pump sizing matters more than a figure chosen at random based on the unit’s appearance.
Heating capacities exceeding the nominal cooling capacity
The Fujitsu data sheet presents a particularly interesting aspect.
The 9,000 BTU version offers:
- 9,000 BTU/h nominal cooling capacity;
- cooling modulation from 3,100 to 12,100 BTU/h;
- 12,000 BTU/h nominal heating capacity;
- a heating range from 2,800 to 14,500 BTU/h.
The 12,000 BTU version offers:
- 12,000 BTU/h nominal cooling capacity;
- modulation from 3,100 to 13,800 BTU/h;
- 14,000 BTU/h nominal heating capacity;
- a heating range of 2,800 to 15,000 BTU/h.
This modulation capability is one of the advantages of Inverter technology. Instead of operating only at full power and then stopping, the compressor can adjust its operation to the room’s needs.
In a residential area like the one shown in the photo, this promotes a more consistent temperature and reduces significant fluctuations between cycles.
Particularly high energy efficiency
According to the technical data sheet provided by Fujitsu, the 09KMAS1 achieves a TRÈS2 rating of 30.0, while the 12KMAS1 has a rating of 27.5.
The regional V CPSC2 values are, respectively:
- 9,9 for the 9,000 BTU system;
- 8,5 for the 12,000 BTU system.
Both configurations are also presented with ENERGY STAR ratings, including the cold-climate designation in Fujitsu’s documentation.
For a homeowner comparing different wall-mounted heat pumps in Franklin, Montreal, Laval, Longueuil, on the North Shore or the South Shore, these figures are much more useful than a simple claim that a unit is “efficient.”
They make it possible to genuinely compare the performance of different systems.
Heating down to -15 °C: what this means in practical terms
Fujitsu specifies an operating range in heating mode from -15 °C to 24 °C for both Altair 700 units. In cooling mode, the units can operate between -10 °C and 50 °C.
This information must be interpreted correctly.
The fact that a heat pump can operate at -15 °C does not automatically mean that it can cover the entire heating load of any home on its own at that temperature.
Actual demand depends in particular on:
- insulation;
- floor area;
- building airtightness;
- windows;
- room layout;
- number of exterior walls;
- outdoor temperature;
- of the heat pump’s exact capacity.
That is why we always distinguish between minimum operating temperature and capacity required to heat an entire building.
From R-32 to a 19 dB sound level: the technical details that matter every day
A new generation from Fujitsu operating with R-32
The AIRSTAGE Altair 700 series uses R-32 refrigerant.
Fujitsu documentation compares a global warming potential of 675 for R-32 with 2,088 for R-410A, representing a reported 68% reduction in GWP.
For the homeowner, this difference may seem abstract, but for us HVAC installers, the refrigerant change also has practical implications.
A new R-32 heat pump must be installed and commissioned according to the methods, equipment, and requirements applicable to this refrigerant. Refrigerant connections, evacuation, testing, and system handling must be carried out rigorously.
1/4 in. and 3/8 in. refrigerant lines
For both Altair 700 capacities, Fujitsu specifies:
- 1/4 in. for the liquid line;
- 3/8 in. for the gas line.
The minimum piping length is 10 ft, while the maximum length can reach 66 ft. The maximum permitted height difference is 49 ft. The documentation also indicates a factory charge covering up to 49 ft of piping.
These figures are particularly important when the indoor unit must be installed in an architecturally constrained location.
The pipe route should never be improvised solely to shorten the work time. We must strike a balance between:
- compliance with the manufacturer’s limits;
- installation appearance;
- future access;
- pipe protection;
- proper condensate drainage;
- outdoor unit location.
A relatively compact power supply
The Altair 700 series operates at 208 to 230 V, 60 Hz, single-phase, with a 15 A circuit breaker specified in the technical data sheet.
The maximum current specified in heating is 9.4 A for both capacities. In cooling, the maximum is 6.4 A for the 9,000 BTU model and 6.9 A for the 12,000 BTU model.
Before each installation, however, we check the exact model and the nameplate requirements of the equipment actually delivered.
This preliminary check prevents discovering an electrical incompatibility once the unit is already mounted on the wall.
The low sound level is particularly relevant in this room
The photo gives the impression of a residential space used daily: finished wall, window, recessed lighting, and interior masonry. In a place like this, the indoor unit’s sound level has a direct impact on comfort.
The Fujitsu Altair 700 can go as low as 19 dB(A) in cooling and 21 dB(A) in heating in quiet mode.
At the higher speeds, Fujitsu indicates:
- 30/33 dB(A) at low speed;
- 35/38 dB(A) at medium speed;
- 40/42 dB(A) at high speed.
The ventilation offers four speeds plus an automatic mode.
This quiet operation is useful when a unit is located near a relaxation area, office, or space where conversation and silence are important.
A compact indoor unit despite its capabilities
Both versions use an indoor unit measuring approximately:
- 32 13/16 in. wide;
- 10 5/8 in. high;
- 8 3/4 in. deep.
It weighs approximately 22 lb.
These dimensions partly explain why the system could be integrated into the visible space above the window.
But “compact” does not mean that the required clearances can be eliminated. A wall-mounted heat pump draws air in particularly through its upper section. The proximity of the ceiling must therefore always be considered during planning.
The ProCore coils and washable filters
Fujitsu equips this series with ProCore coils, described in the documentation as being made of highly corrosion-resistant copper.
The indoor unit also has washable air filters.
To preserve system performance, these filters must remain accessible and be cleaned periodically.
A unit installed in a place where it is practically impossible to open the panel or remove the filters quickly becomes problematic. This is another reason why we incorporate accessibility into our planning before drilling.
Integrated Wi-Fi simplifies everyday control
The Altair 700 series includes integrated Wi-Fi connectivity with the AIRSTAGE mobile app.
The homeowner can therefore manage the system remotely, which can be useful for adjusting the temperature before arriving home or more easily controlling an area that is not occupied continuously.
The documentation also mentions several optional controller and interface options, including solutions compatible with BACnet and Modbus for certain more advanced applications.
An often-overlooked detail: dehumidification in summer
A wall-mounted heat pump does more than simply lower the temperature.
The Fujitsu specifications state a moisture-removal capacity of:
- 1.38 L/h for the 9,000 BTU model;
- 1.73 L/h for the 12,000 BTU model.
In a room located in the lower part of a house or simply subject to significant summer humidity, this aspect can make a noticeable difference in perceived comfort.
Two rooms displaying 23 °C can feel very different if one retains high humidity and the other does not.
Mistakes we avoid when installing above a window
This Franklin project illustrates several mistakes we seek to prevent when installing wall-mounted heat pumps:
- Installing the unit too close to the ceiling, to the point of obstructing air intake.
- Off-centering it unnecessarily, which can compromise air distribution or create a visually unbalanced result.
- Ignoring the window opening or its trim.
- Choosing the wall solely based on the shortest piping route.
- Directing the airflow straight toward a permanently occupied area.
- Creating a drain route without an adequate slope.
- Making the filters difficult to remove.
- Drilling near a masonry structure without sufficient planning.
- Choosing a capacity based solely on square footage.
- Overlooking future access for maintenance and repairs.
In a professional HVAC installation, these invisible decisions often determine whether the homeowner will be satisfied five or ten years later.
Proper sizing remains more important than the largest BTU number
Since the Altair 700 is available in 9,000 and 12,000 BTU, it may be tempting to automatically choose the higher capacity.
That’s not how we work.
Instead, we assess the heat load and the characteristics of the area. A properly sized heat pump can modulate more effectively, maintain a consistent temperature, and control humidity.
Conversely, choosing a unit that is too large simply “to be sure” can be a poor strategy.
The performance of a Fujitsu heat pump depends as much on its sizing and installation as on the figures printed in its specification sheet.
ENERGY STAR and financial assistance: verify the exact combination
Fujitsu documentation classifies the Altair 700 systems presented in the specification sheet as ENERGY STAR, including categories related to cold climates.
This classification is relevant when a homeowner is reviewing financial assistance programs applicable to heat pumps.
However, the brochure alone does not confirm a specific subsidy amount in Quebec for this Franklin installation. Programs may require an exact combination of indoor and outdoor units, a certification reference, and several conditions specific to the building and applicant.
We therefore always prefer to validate the exact combination installed and the applicable program criteria rather than present a subsidy as automatically guaranteed.
What this Franklin installation demonstrates particularly well
This project is not spectacular because it involves an extraordinary amount of equipment. It is interesting because it demonstrates how an apparently simple installation requires several constraints to be resolved simultaneously.
We had a wall with:
- a window occupying the central area;
- limited clearance above;
- a brick structure in the immediate vicinity;
- an interior finish that had to be preserved;
- a need for consistent air distribution throughout the room.
The Fujitsu AIRSTAGE Altair 700 was integrated neatly into this space without blocking the window or visually encroaching on the masonry.
That is exactly the approach we take at AirGreen on our wall-mounted heat pump projects, whether in Franklin, Montreal, Laval, Longueuil, on the North Shore, the South Shore, or elsewhere in Montérégie: we do not look only at where the unit can physically fit. We look for the location where it can operate properly, remain accessible, and integrate neatly into the home.
A good Fujitsu heat pump installation is judged as much by what is visible after the work as by all the technical decisions made before the unit is mounted on the wall.