A flat-roof installation in Saint-Anicet that required particular attention to support, clearance, and durability
At Saint-Anicet, we completed an installation of a Fujitsu AIRSTAGE Altair 700 wall-mounted heat pump in a setting very different from a standard residential ground-level installation. The job-site photo clearly shows the outdoor units installed on a flat roof covered with gravel, near several roof outlets and pieces of equipment. In this type of project, the challenge is not simply to place a condenser on a base: it is necessary to consider mechanical stability, the clearances required for airflow, drainage, vibrations, future maintenance, and winter conditions.
We installed the Fujitsu outdoor units on elevated metal supports, themselves positioned on a structure suited to the roof. This configuration keeps the units above the roofing surface, prevents direct contact with the gravel, and facilitates clearance beneath the equipment.
The photo also shows several elements characteristic of a real job site: a gravel roof, ventilation bases, parapets, neighboring buildings, and an installation that must coexist with the roof’s other mechanical components. These constraints are precisely why an HVAC installation on a flat roof requires much more detailed planning than an installation on a simple ground-level slab.
Why elevate the outdoor unit on a flat roof
For a heat pump used for heating, the outdoor unit produces water during its defrost cycles. When outdoor temperatures are low, this water can freeze.
Placing a heat pump directly on gravel or too close to the roofing membrane would create several potential problems:
- ice accumulation beneath the unit;
- difficult access for technicians;
- partial obstruction of the underside of the unit;
- vibrations transmitted to the roof;
- increased risk of shifting or instability;
- unnecessary exposure of the unit to water and snow accumulation.
In this Saint-Anicet installation, the outdoor units are clearly elevated above the roof on a metal structure. This detail improves both durability and accessibility.
It is also important to ensure that air can circulate freely around the condenser. The outdoor fan must discharge air without immediately encountering a wall, parapet, or other equipment that could cause recirculation.
An installation where vibration matters as much as BTUs
The photograph also shows support points between the unit and its metal structure. On a roof, vibration management becomes particularly important because a minor vibration outside can be transmitted to the building's structure and become noticeable indoors.
At AirGreen, we therefore pay particular attention to:
- the rigidity of the support;
- leveling the unit;
- the mounting points;
- vibration isolation;
- the distance between the units;
- the routing of the refrigerant lines.
The quality of a heat pump installation is not judged solely when the system starts up. A well-designed installation must remain stable and accessible for several years after commissioning.
The Fujitsu Altair 700: a single-zone wall-mounted heat pump using R-32
The Fujitsu AIRSTAGE Altair 700 series belongs to the H series of single-zone wall-mounted systems.
Fujitsu documentation presents two main capacities:
- 09KMAS1, with a nominal cooling capacity of 9,000 BTU/h;
- 12KMAS1, with a nominal cooling capacity of 12,000 BTU/h.
The exterior photo does not make it possible to identify with certainty which of the two capacities was installed in Saint-Anicet, since the exact number on the nameplate would need to be read. We therefore prefer to retain this qualification rather than arbitrarily assigning a capacity based on the appearance of the condenser.
For both models, Fujitsu uses R-32 refrigerant, a fluid with a reported global warming potential of 675, compared with 2,088 for R-410A. Fujitsu therefore indicates an approximately 68% reduction in GWP.
Heating and cooling capacities
The Fujitsu Altair 700 09KMAS1 version offers:
- 9,000 BTU/h of nominal cooling;
- cooling modulation from 3,100 to 12,100 BTU/h;
- 12,000 BTU/h of nominal heating;
- heating modulation from 2,800 to 14,500 BTU/h.
The version 12KMAS1 provides:
- 12,000 BTU/h of nominal cooling;
- modulation from 3,100 to 13,800 BTU/h;
- 14,000 BTU/h of nominal heating;
- modulation from 2,800 to 15,000 BTU/h.
These modulation ranges are possible thanks to Inverter technology.
Instead of operating only at full capacity and then shutting off completely, the compressor adjusts its operation to the actual load. This variation helps maintain a more stable temperature and limit short cycling when heating needs are low.
Heating down to -15 °C
The Fujitsu Altair 700 is designed to operate in heating mode down to -15 °C.
The operating range published by Fujitsu is:
Cooling: -10 °C to 50 °C
Heating: -15 °C to 24 °C
Fujitsu also indicates that the outdoor unit can provide up to 33% additional heating capacity compared with the stated nominal capacity, depending on operating conditions.
However, this feature must be interpreted correctly. A minimum operating temperature does not automatically mean that the heat pump can cover all of a building’s heat losses when the thermometer reaches -15 °C.
In Saint-Anicet, as with our projects in Montreal, Laval, Longueuil, the North Shore, and the South Shore, we must always take the building’s actual load into account.
This load depends in particular on:
- of the floor area;
- of the insulation;
- of the fenestration;
- of air infiltration;
- of the orientation;
- of the room configuration;
- of the supplemental heating system;
- of the building’s use.
Very high energy efficiency for a wall-mounted system
The published ratings for the Altair 700 series are particularly interesting.
Fujitsu Altair 700 9,000 BTU
The 09KMAS1 model displays:
- EER2: 30.0;
- HSPF2 Region V: 9.9;
- SEER2: 16.4;
- COP2: 4.64.
Fujitsu Altair 700 12,000 BTU
The 12KMAS1 model displays:
- EER2: 27.5;
- HSPF2 Region V: 8.5;
- SEER2: 13.5;
- COP2: 4.32.
The technical data sheet provided by Fujitsu also lists both systems with the ENERGY STAR, ENERGY STAR Cold Climate, and ENERGY STAR Most Efficient classifications.
For a homeowner looking for an efficient wall-mounted heat pump in Saint-Anicet, this data provides a much more precise idea of performance than a simple nominal BTU capacity.
A compact outdoor unit, ideal for a crowded roof
In the job-site photo, the Fujitsu unit takes up relatively little space despite the presence of several pieces of equipment on the roof.
The documentation indicates the following for the outdoor unit:
- width: 799 mm, or approximately 31 7/16 in.;
- height: 542 mm, or approximately 21 5/16 in.;
- depth: 290 mm, or approximately 11 7/16 in;
- weight: approximately 32 kg or 71 lb.
This compact format is especially useful on a roof where the available space is shared by several mechanical installations.
However, we must maintain sufficient clearance between and around the units so as not to compromise airflow.
A compact unit should never be used as an excuse to place several condensers too close together.
What this rooftop installation in Saint-Anicet reveals about the technical details that really matter
Refrigerant lines: 1/4 in liquid and 3/8 in gas
Both Altair 700 models use the same piping dimensions:
- liquid: 1/4 in;
- gas: 3/8 in.
The specified minimum piping length is 10 ft, while the maximum length can reach 66 ft.
The refrigerant charge covers up to approximately 49 ft of piping, and the maximum permitted vertical difference is also 49 ft.
These values become even more important during a rooftop installation.
When the indoor unit is several floors below or in a remote part of the building, the refrigerant line run must be planned precisely. The total length, elevation difference, and mechanical routing of the lines must be checked before finalizing the outdoor unit location.
The ability to accommodate 66 ft of piping provides greater flexibility
In urban or commercial projects, the place where we can locate the outdoor unit is not always directly behind the indoor unit.
A roof like the one shown in the photo can become the solution when:
- the exterior walls are difficult to access;
- the owner wants to preserve the façade;
- floor space is limited;
- the units must be grouped in a mechanical area;
- the building configuration requires a long run.
The Altair 700’s maximum 66 ft of piping can therefore facilitate certain projects, provided all Fujitsu requirements are met.
208–230 V power supply with a 15 A circuit breaker
The Altair 700 series operates on a:
208 to 230 V / 60 Hz / single-phase
The documentation specifies a 15 A circuit breaker for both capacities.
The 09KMAS1 model has a maximum current of:
- 6.4 A in cooling mode;
- 9.4 A in heating mode.
The 12KMAS1 model has a maximum current of:
- 6.9 A in cooling mode;
- 9.4 A in heating mode.
This relatively low electrical demand is an advantage in some buildings where panel capacity must be carefully managed.
Nevertheless, we always verify the electrical circuit according to the installed model and the requirements applicable to the actual project.
Outdoor unit noise and choosing its location
Another interesting consideration for a rooftop installation is the condenser’s sound level.
For the 09KMAS1 model, Fujitsu indicates approximately:
- 44 dB(A) in cooling mode;
- 47 dB(A) in heating mode.
For the 12KMAS1:
- 48 dB(A) in cooling mode;
- 50 dB(A) in heating mode.
The series also includes a low-noise outdoor operating mode.
Even with relatively quiet equipment, positioning remains important. A unit installed near a bedroom, balcony, or reverberant wall may seem much louder than an identical unit placed in an open environment.
On a roof, we have the advantage of being able to move the equipment farther away from certain occupied areas, but we must also consider structural vibrations.
The roof imposes particular requirements during winter
An installation like the one in Saint-Anicet must be designed to operate throughout all four seasons.
In winter, we must take into account:
- snow accumulation;
- ice produced during defrost cycles;
- wind;
- support stability;
- accessibility for servicing;
- clearance around the outdoor heat exchanger.
The Fujitsu documentation also lists various optional accessories for the outdoor unit, including:
- a hail guard;
- a snow hood;
- a wind deflector.
These accessories are not necessarily required for every installation, but they clearly show that the outdoor environment is an integral part of a heat pump system’s design.
Why we avoid placing a unit directly on the roof
A mistake we sometimes encounter in older installations is an outdoor unit resting directly, or almost directly, on the roof surface.
This can create several problems:
- Insufficient drainage during defrosting.
- Ice accumulation around the base.
- Transmission of vibrations to the building.
- Difficult access beneath the unit.
- Increased exposure to standing water.
- Snow obstruction.
- More difficult maintenance.
In contrast, the photo of our installation in Saint-Anicet clearly shows the units elevated and secured on dedicated supports.
It is a visually simple detail, but technically essential.
Future maintenance must be planned from the time of installation.
A technician must be able to reach the condenser without dismantling other equipment or walking in a dangerous area of the roof.
During planning, we therefore ask ourselves:
- will we be able to remove the service panels?
- are the refrigerant valves accessible?
- will we be able to clean the heat exchanger?
- will we be able to measure the pressures or temperatures?
- will we be able to work without blocking another unit?
The photograph shows that the equipment is positioned with visible access around the main sides.
For us, HVAC maintenance therefore begins on the day of installation.
Integrated Wi-Fi and remote controls
The Fujitsu Altair 700 also offers integrated Wi-Fi connectivity with the AIRSTAGE mobile app.
This feature notably makes it possible to manage certain heat pump settings remotely.
For a homeowner in Saint-Anicet who does not occupy their residence year-round, this option can be particularly convenient.
The system can also support several accessories and control interfaces, including certain wired controls as well as solutions compatible with BACnet and Modbus for more advanced integrations.
Fujitsu also includes a wireless remote control with the indoor unit.
Indoors: as low as 19 dB(A)
Even though the photo of this project focuses on the outdoor installation, the indoor unit’s noise level is one of the Altair 700’s advantages.
In quiet mode, Fujitsu announces:
- 19 dB(A) in cooling;
- 21 dB(A) in heating.
At high speed, the indoor unit reaches approximately 40 dB(A) in cooling and 42 dB(A) in heating.
The fan offers four speeds in addition to automatic mode.
This low noise level is appreciated in a bedroom, living room, open-concept area, or office, where the constant noise of a heat pump can become more significant than homeowners anticipate when making their purchase.
ProCore coils and washable filters
According to Fujitsu, the Altair 700’s indoor unit is equipped with highly corrosion-resistant copper ProCore coils.
The system also has washable air filters.
To maintain good airflow, we recommend inspecting and cleaning them regularly before they become completely clogged.
Periodic cleaning helps preserve:
- airflow;
- heating capacity;
- cooling capacity;
- dehumidification;
- noise level;
- energy efficiency.
Rebates: the exact model number remains essential
Fujitsu documentation associates the Altair 700 models with the ENERGY STAR Cold Climate classifications.
This may be relevant to financial assistance programs applicable to heat pumps.
However, we never calculate a rebate solely based on the commercial name “Fujitsu Altair 700.”
The exact combination must be verified.
For the 9,000 BTU:
- indoor unit: ASUH09KMAS;
- outdoor unit: AOUH09KMAS1.
For the 12,000 BTU:
- indoor unit: ASUH12KMAS;
- outdoor unit: AOUH12KMAS1.
The specific model, its certification number, and the program rules in effect at the time of installation must be verified before confirming eligibility or an amount.
This Saint-Anicet project clearly represents the difference between installing a machine and designing an installation.
The photograph of this installation does not simply show a Fujitsu heat pump placed on a roof. It shows several technical decisions made before the system was even powered on.
We had to take into account:
- the roof structure;
- the presence of gravel;
- other mechanical equipment;
- the spacing between the units;
- the height of the supports;
- vibrations;
- service access;
- the piping route;
- future snow and ice accumulation;
- the clearance required for the outdoor fan.
That is exactly what defines our approach at AirGreen.
A wall-mounted heat pump installation in Saint-Anicet should never be treated as a simple task involving securing an indoor unit and connecting an outdoor condenser.
The system must operate properly in July, but also remain stable, accessible, and efficient in January.
AirGreen: Fujitsu heat pump installation in Saint-Anicet and Greater Montreal
We carry out HVAC installations in Saint-Anicet, as well as in Montreal, Laval, Longueuil, the North Shore, and the South Shore.
The Fujitsu AIRSTAGE Altair 700 combines several interesting features:
- R-32 refrigerant;
- Inverter technology;
- heating down to -15°C;
- high seasonal efficiency;
- built-in Wi-Fi;
- indoor operation from 19 dB(A);
- compact dimensions;
- piping that can reach 66 ft;
- ENERGY STAR-rated systems according to the published combinations.
But even an excellent unit must be supported by a well-planned installation.
In Saint-Anicet, this flat-roof installation illustrates precisely what we strive for: a properly positioned, elevated, accessible Fujitsu heat pump integrated into the existing mechanical environment, to support its operation and maintenance for many years.