In Les Coteaux, a rooftop installation that required precise execution down to the connections
This installation in Les Coteaux immediately stands out because of a less common feature in residential settings: the outdoor unit of the Fujitsu AIRSTAGE Altair 700 wall-mounted heat pump was installed on a flat roof rather than on the ground or on a wall bracket.
The photo taken during the work provides a view of the project at a particularly interesting stage. The outdoor unit’s service panel is open, the electrical connections are accessible, the refrigerant lines run directly to the unit, and our technician is completing the final stages of the HVAC installation. The outdoor electrical panel is also nearby, while the unit itself rests on a metal structure above the roofing.
This type of configuration significantly changes how we need to plan the project.
With a conventional ground-level installation, we mainly have to contend with snow, foot traffic, fences, and foundations. On a flat roof, the considerations are different: unit stability, vibrations, service access, piping length, wind exposure, roof protection, electrical power supply, and positioning relative to other mechanical equipment.
In Les Coteaux, our goal was therefore to create an installation that would not only be functional at startup, but also accessible and durable for years to come.
A Fujitsu Altair 700 genuinely designed for a compact installation
The Fujitsu documentation provided for this project presents the AIRSTAGE Altair 700 H series in two single-zone configurations: the 09KMAS1 and the 12KMAS1. These are systems offering a nominal cooling capacity of 9,000 BTU/h and 12,000 BTU/h, respectively. The stated nominal heating capacities are 12,000 BTU/h and 14,000 BTU/h.
In the photograph of our installation in Les Coteaux, the Fujitsu AIRSTAGE outdoor unit is clearly visible, but the nameplate is not legible enough to reliably determine which of the two capacities is installed. We therefore prefer to preserve this distinction rather than arbitrarily assigning a capacity based on the cabinet size.
Both models also use an outdoor unit with the same dimensions, according to the technical data sheet:
- 799 mm wide, or 31 7/16 in;
- 542 mm high, or 21 5/16 in;
- 290 mm deep, or 11 7/16 in;
- net weight of approximately 32 kg or 71 lb.
This shallow depth is particularly useful on a roof, where each piece of equipment must use space efficiently without blocking circulation areas or access to other mechanical components.
Why install the outdoor unit on a roof?
An outdoor unit does not necessarily need to be installed near ground level.
Depending on the building’s configuration, a rooftop installation may sometimes be the most logical solution.
In Les Coteaux, this arrangement helps keep the mechanical equipment away from outdoor areas used by occupants. It can also simplify certain piping routes when the indoor unit is located near the roof or when a direct route downward is not desirable.
A rooftop installation can be particularly appropriate when:
- the area around the building is limited;
- passageways must remain clear;
- the façades are not suitable for wall mounting;
- the indoor unit is located near the top floor;
- the lines can be routed more efficiently from the roof;
- Several mechanical systems are already grouped on a mechanical roof.
However, this choice also requires greater rigor.
A roof is not a surface where we can simply place a heat pump and walk away.
A stable metal support to keep the equipment above the roof
The photo shows that the Fujitsu unit is installed on a horizontal metal structure, rather than directly on the roof covering.
This point is important for several reasons.
First, the equipment’s weight must be transferred properly. In addition, a heat pump contains a compressor and a fan that generate slight vibrations when operating. An inadequate base can transmit these vibrations to the building structure.
Elements used to isolate and stabilize the contact between the unit and its support can also be seen beneath the support points.
For us, the quality of a rooftop installation therefore begins even before the refrigeration connections are made.
We must ensure that the unit is:
- properly level;
- securely fastened;
- placed on a suitable base;
- sufficiently clear of the roof surface;
- accessible for future service work.
The service panel had to remain completely unobstructed
The job-site photo shows the heat pump’s electrical and service panel open.
This is an important detail because it illustrates exactly why we always plan the space around an outdoor unit with future maintenance in mind.
A technician must be able to access the electrical terminals, electronic components, and refrigeration connections without having to move the unit or dismantle a structure that was installed too close.
On a rooftop, this aspect becomes even more important because the options for moving the unit are more limited.
We therefore avoid positioning a heat pump against a parapet, duct, mechanical enclosure, or other equipment where opening its service panel would become difficult.
The refrigeration connections visible on this installation
On the lower part of the outdoor unit, the two brass service valves associated with the refrigeration circuit are clearly visible.
Fujitsu documentation indicates that both versions of the Altair 700 use:
- 1/4 in. for the liquid line;
- 3/8 in. for the gas line.
These two copper lines transfer refrigerant between the indoor and outdoor units.
The route must be properly sized, insulated, and protected.
Fujitsu specifies a minimum piping length of 3 m or 10 ft, and a maximum length of 20 m or 66 ft. The factory charge covers up to 14.9 m or 49 ft, while the maximum permitted vertical difference is also 14.9 m or 49 ft.
This data is particularly useful for a rooftop installation, since the height difference between the wall-mounted unit and the outdoor unit may be greater than in a conventional installation behind an exterior wall.
R-32 is clearly identifiable on the installed unit
The label R32 is visible in several places on the photographed outdoor unit.
The Altair 700 belongs to the new generation of Fujitsu systems using R-32 refrigerant.
According to the manufacturer's documentation, the global warming potential indicated for R-32 is 675, compared with 2088 for R-410A, which Fujitsu presents as a 68% reduction in GWP.
For us, this change is not merely a line in a brochure.
The type of refrigerant directly influences the work methods and precautions required during installation.
The project photo also shows the regulatory labels associated with the refrigerant, as well as the service valves accessible during the work.
A R-32 heat pump installation requires the technician to know exactly which product they are handling and to apply the corresponding procedures during pressurization, evacuation, and commissioning.
Evacuation: an invisible step once the project is complete
Most homeowners see the completed heat pump, but rarely the steps that precede its commissioning.
After the mechanical connections, the refrigeration circuit must be properly prepared before opening the outdoor unit's valves.
This part of the work is essential.
The lines must be clean, leak-tight, and free of moisture before the system is commissioned. An installation that looks beautiful can nevertheless develop premature problems if the refrigeration steps have been neglected.
That is precisely why we place as much importance on what happens behind the service panel as we do on the exterior finish.
A 208 to 230 V power supply on a 15 A circuit
The Fujitsu technical data sheet indicates a power supply of the following for the 09KMAS1 and 12KMAS1 models:
- 208 to 230 V;
- 60 Hz;
- single-phase;
- with a 15 A circuit breaker.
The photo also shows an outdoor electrical enclosure installed immediately next to the heat pump.
This proximity makes it easier to access the electrical disconnect during servicing.
The electrical installation of a heat pump must be designed as an integral part of the HVAC project. The circuit, protection, and connection method must be adapted to the exact model installed.
That is why we verify this data before commissioning, rather than treating electrical work as a last-minute formality.
This rooftop project in Les Coteaux demonstrates what a professional installation adds to the performance of the Fujitsu Altair 700
An Inverter heat pump that modulates instead of simply starting and stopping
One of the main technical advantages of the Fujitsu AIRSTAGE Altair 700 is its Inverter compressor.
Rather than operating only at a fixed capacity, the equipment can modulate its output according to demand.
For the 09KMAS1 version, cooling capacity ranges from 3,100 to 12,100 BTU/h, while heating capacity extends from 2,800 to 14,500 BTU/h.
The 12KMAS1 offers a range of 3,100 to 13,800 BTU/h in cooling and 2,800 to 15,000 BTU/h in heating.
This allows the heat pump to reduce its output as the building approaches the desired temperature, then increase it again when demand becomes greater.
For the occupant, this generally translates into a more stable temperature and fewer abrupt fluctuations.
Particularly impressive efficiency for these small capacities
The Fujitsu specifications sheet lists a 30.0 TRÈS2 for the 9,000 BTU version and 27.5 for the 12,000 BTU version.
The regional V CPSC2 is listed as 9.9 for the 09KMAS1 and 8.5 for the 12KMAS1.
The two configurations listed in the documentation also have ENERGY STAR ratings, including references associated with cold climates.
This performance may be of interest to a homeowner who wants to reduce their reliance on electric resistance heating during part of the winter.
Actual performance nevertheless remains linked to sizing, the building envelope, and how the unit is used.
Heating down to -15 °C according to Fujitsu
The manufacturer’s stated heating operating range extends down to -15 °C, while the cooling range extends up to 50 °C and down to -10 °C.
This explains why an outdoor installation must be designed with very different conditions in mind.
A rooftop unit is more exposed to wind than a unit installed at ground level against a wall. It may also be directly exposed to snow.
The unit’s positioning and immediate surroundings therefore become important for maintaining airflow.
Fujitsu also lists a snow hood, a wind deflector, and a hail guard among the range’s optional accessories, according to the series documentation.
This demonstrates how much external conditions can influence the final configuration choice.
A relatively quiet outdoor unit, well suited to a rooftop
The stated outdoor sound level varies according to capacity.
For the 09KMAS1, Fujitsu indicates 44 dB(A) in cooling and 47 dB(A) in heating.
For the 12KMAS1, the values are 48 dB(A) and 50 dB(A).
On a roof, the distance from occupied rooms can help reduce the perception of outdoor noise.
Nevertheless, it is important to prevent vibrations from being transmitted to the building structure. This is one reason why the quality of the support and mounting points must be taken seriously.
The indoor model can operate at only 19 dB(A)
Indoors, the Altair 700 can operate at a rated sound level of only 19 dB(A) in cooling in quiet mode, and 21 dB(A) in heating.
At high speed, the levels are 40 dB(A) in cooling and 42 dB(A) in heating.
The unit has four fan speeds plus automatic mode.
Airflow ranges from approximately 260 m³/h in quiet mode to 680 m³/h at high speed.
This range allows the system to operate quietly when low capacity is sufficient, while providing higher airflow when the temperature needs to be changed quickly.
Integrated Wi-Fi and remote control
The Altair 700 documentation also indicates integrated Wi-Fi connectivity, notably enabling use of the AIRSTAGE mobile app for monitoring and remote control.
This feature is convenient for a unit installed in a building where occupants want to adjust the settings without always being present on-site.
The series is also compatible with several control accessories, including certain wired controllers and BACnet or Modbus interfaces, depending on the selected configuration.
A roof requires special attention to the routing of the lines
On a flat roof like the one shown in the photo, the refrigerant lines must be routed so they do not create a vulnerable point.
The lines must be adequately protected, and their insulation must remain intact.
We must also consider building penetration when necessary. The roof’s watertightness must never be compromised simply to shorten the route of the lines.
An error in this area can cost much more than the difference of a few feet of piping.
That is why the route is planned based on the entire building, not just the shortest distance between the two units.
Mistakes to avoid when installing a heat pump on a roof
Placing the unit directly on the membrane
A heat pump must have a suitable base. Weight, vibrations, and seasonal movement can affect the roof if the installation is improvised.
Blocking the service panel
The photo from Les Coteaux clearly shows all the space needed to access the electrical panel and the connections.
This access must remain available after the installers leave.
Leaving the lines unprotected
Sun, weather, and foot traffic on a roof can gradually damage exposed lines.
Neglecting vibrations
Even a small Inverter unit produces vibrations. The mounting structure must limit their transmission to the building.
Forgetting winter conditions
A roof may be exposed to more wind and snow than a protected ground-level location.
The choice of location must therefore take all four seasons into account.
Neglecting future roof access
A heat pump will eventually require inspection, cleaning, or diagnostics.
The installation must therefore remain reasonably accessible to a technician.
The job-site image also reveals the difference between an installed machine and a commissioned machine
It is easy to look at a completed heat pump and believe that the essential work consists of mounting two units and connecting a few lines.
This photograph taken in Les Coteaux shows the other side of the trade.
The service panel is open. The refrigerant connections are accessible. The electrical conductors must be connected to the correct terminals. The lines must be checked. The system must be prepared before commissioning. Every connection must be inspected.
This is often the stage of the project when the technical quality of an HVAC installation is determined.
An attractive finish is important, but a heat pump must above all be commissioned under the conditions specified by the manufacturer.
Rebates must be verified using the exact combination
The Altair 700 models listed in the technical specifications have ENERGY STAR ratings, including cold-climate ratings.
However, when a customer wants to determine their eligibility for a rebate, we do not rely solely on the trade name “Fujitsu Altair 700.”
We verify the exact combination of the indoor and outdoor units, the applicable references, and the program criteria at the time of installation.
Programs and rebate amounts can change. Therefore, a subsidy promise based solely on a brochure or the heat pump brand is not a sound approach.
An installation different from our conventional wall-mounted projects
At AirGreen, we install heat pumps in a wide variety of environments in Montreal, Laval, Longueuil, on the North Shore and South Shore, as well as in several municipalities west and southwest of Montreal.
Some installations require an exterior wall bracket. Others call for a slab or ground support. Here, in Les Coteaux, choosing a rooftop installation required a different approach.
The challenge was not finding a few inches above an interior door or protecting the unit from ground-level buildup.
Instead, we had to design a clean mechanical installation on a flat roof, ensure the unit's stability, maintain access to the electrical and refrigerant connections, and properly coordinate the routing of the lines.
It is this ability to adapt the installation method to the actual building that distinguishes a well-planned project from a generic installation.
A properly installed Fujitsu Altair 700 begins with details that are almost never visible.
This Fujitsu AIRSTAGE Altair 700 heat pump installation in Les Coteaux nicely sums up our approach at AirGreen.
The unit offers interesting features: Inverter technology, R-32 refrigerant, high efficiency, built-in Wi-Fi, quiet operation, and heating down to -15 °C according to Fujitsu documentation.
But none of these features can replace a properly executed installation.
The metal base, access to the service panel, the nearby electrical cabinet, the refrigerant connections, line protection, and placement planning are just as important as the efficiency figures listed on the technical data sheet.
This is precisely what this photo taken during our work shows: a heat pump still open and in the middle of the connection phase, before everything is closed up and the system begins heating and cooling quietly.
For us, this is where the real work behind a wall-mounted heat pump installation in Les Coteaux takes place.