A Fujitsu heat pump installed on a rooftop with an elevated structure adapted to the realities of Quebec’s climate
In Saint-Chrysostome, our AirGreen team completed an installation of a Fujitsu AIRSTAGE Altair 700 wall-mounted heat pump in a configuration that required particular attention to the outdoor unit’s support. Here, the machine could not simply be placed on the ground against a foundation. It had to be installed on a flat roof already occupied by ventilation equipment and surrounded by mature vegetation.
The site photograph clearly shows the solution chosen: the Fujitsu outdoor unit is mounted on an elevated metal structure, itself installed on two long wooden bases resting on support blocks or slabs. This configuration keeps the heat pump well above the roof surface while distributing the load and creating generous space beneath the unit.
For a rooftop heat pump project in Saint-Chrysostome, this detail is extremely important. In winter, an outdoor unit must contend with snow, ice, defrost water, and buildup around the building. In summer, it must benefit from sufficient airflow and remain accessible for maintenance.
This project perfectly illustrates why a proper HVAC installation relies as much on analyzing the building as on selecting the model.
An elevated structure designed to allow the outdoor unit to breathe
One of the most visible elements of this installation is the height of the support.
The Fujitsu unit rests on a stable metal structure that creates several inches of clearance between the base of the machine and the roof. The metal crossbars properly support the unit’s feet, while the long wooden pieces beneath the supports help distribute the load.
This elevation provides several concrete benefits:
- better drainage of the water produced during defrosting;
- reduced risk of snow reaching the bottom of the heat exchanger directly;
- reduced permanent contact with roof moisture;
- easier access to connections and components during HVAC maintenance;
- better visibility and organization of the lines;
- increased protection of the machine against debris buildup.
On a flat roof, these details make a real difference over the long term.
Defrosting: a frequently overlooked aspect of heat pump installations
In heating mode, a heat pump draws heat from the outdoor air. When the temperature drops and humidity increases, frost can form on the outdoor coil.
To maintain its performance, the system automatically initiates a defrost cycle.
During this cycle, water from the melted ice drains beneath the unit. If the heat pump is placed too close to the roof, this water can freeze around its base and gradually create a significant mass of ice.
In Saint-Chrysostome, we avoided this type of problem by installing the outdoor unit high enough.
The space available beneath the unit allows water to disperse more easily and reduces the risk of ice rising directly to the frame.
An installation near an existing ventilation component
The photo also reveals another site constraint: the outdoor unit is located immediately beside an existing ventilation outlet on the roof.
For this type of installation, we must take several elements into account at the same time:
- maintain the necessary clearances around the unit;
- avoid blocking or disrupting the existing ventilation;
- maintain reasonable access to the system;
- choose an orientation that promotes airflow;
- avoid forcing a future technician to dismantle part of the installation simply to access the service panels.
These constraints are precisely why the positioning of an outdoor heat pump should never be improvised.
A roofing environment that requires careful planning
At this property in Saint-Chrysostome, the roof is covered with gravel, and several building elements are located nearby.
In particular, we note:
- a large ventilation duct or vent;
- roof parapets;
- a strong presence of trees around the building;
- other relatively nearby roof sections;
- a technical space that must remain accessible.
We therefore need to think not only about where the heat pump can physically fit, but also about how it will operate in that environment.
For example, installing the unit too close to an obstacle could restrict air discharge. Placing it too low would increase risks related to snow and defrosting. Positioning it too far from the point where the lines enter the building could unnecessarily increase the piping length.
The final result is therefore a technical compromise among several constraints.
Fujitsu AIRSTAGE Altair 700: a compact, quiet, and highly efficient R-32 wall-mounted heat pump
The Fujitsu AIRSTAGE Altair 700 used for this type of project belongs to Fujitsu’s H single-zone series. The documentation provided for this range covers two configurations: 09KMAS1 and 12KMAS1. They correspond, respectively, to rated cooling capacities of 9,000 and 12,000 BTU/h.
Since the full model number is not legible in the site photograph, it would be imprudent to confidently attribute either of these two capacities to the photographed unit. We therefore prefer to present both configurations documented by Fujitsu.
Performance of the 9,000 BTU version
For the 09KMAS1, Fujitsu indicates:
- rated cooling capacity: 9,000 BTU/h;
- cooling range: 3,100 to 12,100 BTU/h;
- rated heating capacity: 12,000 BTU/h;
- heating range: 2,800 to 14,500 BTU/h;
- SEER2: 30,0;
- HSPF2 Region V: 9,9;
- EER2: 16,4.
A SEER2 of 30.0 places this configuration among the highest-efficiency wall-mounted units in its category.
Performance of the 12,000 BTU version
For the 12KMAS1, the technical data sheet indicates:
- rated cooling capacity: 12,000 BTU/h;
- cooling range: 3,100 to 13,800 BTU/h;
- rated heating capacity: 14,000 BTU/h;
- heating range: 2,800 to 15,000 BTU/h;
- SEER2: 27,5;
- HSPF2 Region V: 8,5;
- EER2: 13,5.
These modulation ranges are particularly interesting because they show that the system can operate at reduced capacity when demand is low.
Inverter technology: why modulation matters
The Fujitsu Altair 700 uses Inverter technology.
Unlike a traditional unit that operates essentially at full capacity and then stops, an Inverter compressor can vary its speed according to the building’s needs.
This makes it possible in particular to:
- to maintain a more stable temperature;
- to reduce the number of abrupt starts;
- to better match consumption to the actual load;
- to improve comfort when demand is low;
- to avoid excessively short cycles under certain conditions.
For a small room, apartment, or specific zone, this modulation capacity is often more important than the nominal BTU figure alone.
Heating down to -15 °C according to Fujitsu
The Altair 700 series is designed to operate in heating mode down to -15 °C, with an official range of -15 °C to 24 °C.
In cooling mode, the indicated operating range is -10 °C to 50 °C.
For a property in Saint-Chrysostome, this data must always be put into context.
The fact that a heat pump can operate down to -15 °C does not automatically mean that it will be sufficient as the sole heating source for all buildings. A home with high heat losses may need supplemental heating well before reaching the unit’s operating limit.
Proper sizing therefore remains essential.
R-32 refrigerant: clearly visible on the installed unit
In the photograph, the identification R32 is clearly visible on the right side of the outdoor unit.
Fujitsu states that R-32 has a global warming potential of 675, compared with 2,088 for R-410A, representing an approximately 68% reduction in GWP in the comparison presented in its documentation.
R-32 therefore significantly reduces the refrigerant’s potential climate impact compared with R-410A.
For the installer, this also means following the methods and procedures appropriate for this type of refrigerant during commissioning.
Refrigerant piping: 1/4 in. liquid and 3/8 in. gas
The Fujitsu Altair 700 uses relatively compact piping.
For both documented models:
- liquid: 1/4 po;
- gas: 3/8 po.
The documentation also indicates:
- minimum length: 10 feet;
- maximum length: 66 feet;
- precharge up to 49 feet;
- maximum vertical difference: 49 feet.
These values give installers good flexibility, particularly for rooftop projects where the outdoor unit may be located far from the indoor unit.
A 208–230 V power supply with a 15 A circuit breaker
The documented Altair 700 configurations operate with a power supply of:
208–230 V / 60 Hz / single-phase
and require a 15 A circuit breaker according to the technical specifications.
The indicated maximum current is:
- 6.4 A in cooling mode for the 09KMAS1;
- 6.9 A in cooling mode for the 12KMAS1;
- 9.4 A in heating mode for both models.
For a heat pump replacement or a project where electrical panel capacity is limited, this detail can be particularly interesting.
A compact outdoor unit suited to technical spaces
The outdoor unit in the Altair 700 series measures approximately:
- 31 7/16 in. wide;
- 21 5/16 in. high;
- 11 7/16 in. deep.
Its net weight is 71 lb.
This shallow depth partly explains why the machine can be integrated relatively easily on a roof already occupied by other equipment.
On the Saint-Chrysostome project, the compact outdoor unit can be positioned very close to a ventilation component while maintaining a circulation and access area.
Up to 19 dB(A) indoors
The Fujitsu Altair 700 indoor unit can operate at only 19 dB(A) in cooling mode on quiet setting.
In heating mode, this level is listed as 21 dB(A).
For the outdoor unit, the specifications indicate:
- 44/47 dB(A) in cooling/heating mode for the 09KMAS1 model;
- 48/50 dB(A) for the 12KMAS1 model.
In rooms where silence is important, such as a bedroom, office, or workspace, this reduced noise level is a real advantage.
Built-in Wi-Fi and app control
The Altair 700 series also includes built-in Wi-Fi connectivity.
The owner can therefore use the AIRSTAGE mobile app to monitor and control the system remotely.
This feature can be particularly useful for:
- adjust the temperature before returning home;
- manage a secondary building;
- monitor a rental space;
- avoid leaving an excessive setpoint while away;
- check certain operating parameters.
Fujitsu also offers several controller and interface options for more advanced installations, including systems compatible with BACnet or Modbus.
Copper ProCore coils
The Altair 700 documentation mentions highly corrosion-resistant copper ProCore coils in the indoor unit.
This detail is beneficial for the equipment’s durability, particularly in a system that may operate for much of the year in heating, cooling, or dehumidification mode.
The available features also include:
- economy mode;
- energy-saving mode;
- minimal heat mode;
- automatic defrosting;
- automatic restart;
- wireless remote control;
- automatic vertical airflow adjustment.
An ENERGY STAR system, but the subsidy must be verified precisely
Fujitsu’s documentation indicates the applicable ENERGY STAR ratings for both models in this series.
For a Saint-Chrysostome homeowner looking for a heat pump subsidy, it is nevertheless important to verify the exact model installed and the program conditions at the time of the project.
We always advise against relying solely on:
- the brand name;
- the “cold climate” designation;
- the ENERGY STAR logo;
- a subsidy amount seen in an advertisement.
Programs generally use specific combinations of indoor and outdoor units, certification numbers, and defined performance criteria.
Why the bases beneath the structure are important
In the photograph, we can see that the metal structure is not simply placed directly on the roof gravel.
It rests on wider support elements that help distribute the weight.
This is an important approach for several reasons.
Load distribution
A small support surface can concentrate more pressure on the roof.
A longer base distributes this load.
Stability
An outdoor unit may be exposed to vibrations and wind-related forces. A more stable base helps keep the support in place.
Roof protection
Limiting direct contact points helps reduce the risk of surface damage.
Access
The structure creates a clear space beneath the heat pump, making it easier to inspect the base and the lines.
A common mistake: choosing the support based solely on price
When we inspect an existing heat pump installation, we regularly see supports that are too low, too narrow, or poorly suited to the building.
An inexpensive support may seem sufficient during the first summer.
The problems sometimes appear later:
- ice beneath the unit;
- sagging;
- instability;
- maintenance difficulties;
- contact with the roof;
- snow accumulation;
- vibrations transmitted to the building.
At AirGreen, we therefore consider the support to be a genuine component of the HVAC installation, not merely an accessory.
What the Saint-Chrysostome photo reveals about the completed work
The final photograph shows a very clear installation.
The Fujitsu AIRSTAGE unit is clearly visible, installed horizontally on its metal support. The feet are secured to the crossbars, the machine is elevated above the roof, and the bases are aligned beneath the structure.
The immediate area in front of the fan remains clear, allowing the air expelled by the outdoor unit to circulate without directly encountering a wall.
The result looks simple, but this visual simplicity is precisely the sign of a well-organized job.
A rooftop installation requires more than a good heat pump
On paper, the Fujitsu Altair 700 offers very attractive specifications: up to 30 SEER2, heating down to -15 °C, R-32 refrigerant, quiet operation, built-in Wi-Fi, and piping that can reach 66 feet.
On the job site, these features only become truly useful if the installation is properly carried out.
This includes:
- select the right location;
- provide a suitable support;
- respect the required clearances;
- plan the refrigerant line routing;
- perform an adequate vacuum;
- check for leaks;
- make the appropriate electrical connections;
- check the drainage;
- test its operation;
- ensure that the unit will remain accessible.
It is the combination of all these steps that turns a simple heat pump sale into a durable installation.
AirGreen in Saint-Chrysostome and throughout the Greater Montreal area
This installation in Saint-Chrysostome reflects the same approach we apply to our heat pump projects in Montreal, Laval, Longueuil, on the North Shore and the South Shore.
We adapt every project to the actual building.
A heat pump installed on a detached house requires a different strategy than a unit installed on a balcony, in a condominium, a commercial building, or on a flat roof.
For this Fujitsu AIRSTAGE Altair 700, our priority was clear: to achieve a stable, sufficiently elevated outdoor installation compatible with the technical space available on the roof.
The result is a properly positioned Fujitsu wall-mounted heat pump designed for daily operation, defrost cycles, and future maintenance.
For a homeowner currently comparing several heat pump quotes, our advice is simple: don’t compare only the brand, the number of BTUs, and the price. Also look at how the contractor plans to install the unit.
The support, height, piping layout, roof protection, service access, and winter management are just as much a part of the system as the compressor itself.