In Saint-Bernard-de-Michaudville, a FUJITSU ORION XLTH installed on a flat roof with a raised structure designed for Quebec winters
This installation carried out by AirGreen in Saint-Bernard-de-Michaudville presents a particularly interesting case: that of a FUJITSU AIRSTAGE ORION XLTH wall-mounted heat pump whose outdoor unit was installed directly on a flat roof, in an environment where mechanical stability, snow, defrost water, and vibration had to be considered as carefully as the machine’s performance.
The project photo reveals several important technical details. We can see an outdoor FUJITSU AIRSTAGE unit using R32 refrigerant, the A2L marking on the side of the cabinet, a raised metal structure, and vibration-dampening supports placed beneath the mounting points. The equipment sits above a gravel-covered roof rather than directly on it.
The nameplate visible in our photo also identifies the outdoor unit as an AOUH24KZAH1, the 24K version in the ORION XLTH family. Fujitsu documentation associates this outdoor unit with the ASUH24KZAS indoor unit.
This is precisely the kind of project that demonstrates why an HVAC installation should never be reduced to simply choosing a brand or a number of BTUs.
An ORION XLTH 24K offering 22,000 nominal BTU/h in cooling
The term “24K” can easily cause confusion when comparing technical specifications.
For the ASUH24KZAS + AOUH24KZAH1 system, Fujitsu indicates:
- 22,000 nominal BTU/h in cooling;
- cooling modulation from 9,100 to 28,900 BTU/h;
- 25,200 nominal BTU/h in heating;
- heating modulation from 8,200 to 36,800 BTU/h.
In other words, this is not simply a 24,000 BTU air conditioner with a heating function added. It is an Inverter heat pump capable of significantly varying its output according to the building’s needs.
This modulation range is important for comfort. When demand is low, the machine can reduce its output rather than constantly operating at maximum capacity. When demand increases, it instead has a valuable reserve of capacity.
For a property located in Saint-Bernard-de-Michaudville, where the heating season accounts for a major share of a HVAC system’s annual use, winter performance characteristics are therefore just as important as cooling efficiency.
Heating down to -26 °C: a feature directly suited to Quebec
The FUJITSU ORION XLTH series is designed for heating in cold climates. The manufacturer indicates a heating operating range down to -26 °C for this entire family of heat pumps.
For the 24K model installed here, the technical specifications provide an even more useful detail: Fujitsu indicates a maximum heating percentage corresponding to approximately:
- 108% of nominal capacity at -15 °C;
- 95% at -21 °C;
- 80% at -26 °C.
These values provide a much more realistic picture of winter performance than a simple BTU figure included in the product name.
A common mistake when comparing wall-mounted heat pumps is to look only at the advertised minimum temperature. Two machines may both be listed as operating at -25 °C or -30 °C, yet not retain the same heating capacity at that temperature.
At AirGreen, we therefore place great importance on low-temperature performance charts, especially for our installations in Montreal, Laval, Longueuil, the North Shore, the South Shore, and rural municipalities around Greater Montreal.
Why did we place this unit on a raised structure?
The most striking feature of this installation in Saint-Bernard-de-Michaudville is undoubtedly the support.
The outdoor unit does not rest directly on the roof gravel. It is installed on a raised four-legged metal structure, positioned to keep the heat pump stable.
This decision is based on several practical considerations.
Keeping the unit clear of winter snow accumulation
A heat pump operating in heating mode must draw in and discharge significant volumes of outdoor air. Excessive snow accumulation around the heat exchanger can become problematic.
On a flat roof, snow can also be moved by the wind, creating accumulations that differ significantly from those observed at ground level.
Elevating the unit therefore creates additional clearance beneath the appliance.
Allowing room for defrost water
During winter, a heat pump must periodically perform a defrost cycle to remove frost accumulated on its outdoor heat exchanger.
This process produces water.
On the page dedicated to the technical specifications of the ORION XLTH, Fujitsu specifies that the outdoor unit includes a base pan heater designed for extremely cold climate regions.
Even with this equipment, the physical positioning of the machine remains important. Water must be able to leave the unit without gradually creating a block of ice immediately beneath the cabinet.
The height visible in our installation helps provide more space for managing winter conditions.
Do not place the heat pump directly on the roof surface
An outdoor unit in this category has a considerable weight. Fujitsu gives an approximate net weight of 53 kg, or 117 lb, for the 24K outdoor unit.
We must therefore consider how this load is supported and stabilized.
The structure visible in the photo makes it possible to create a separate technical platform for the heat pump rather than treating the roof as a simple slab where the unit could be placed without preparation.
Vibration-dampening pads visible at the mounting points
Looking more closely at the photo, we can see the vibration-dampening pads placed under the feet of the outdoor unit.
This detail is important on a roof.
Even a relatively quiet Inverter heat pump has a compressor and a fan in motion. If its vibrations are transmitted directly to a building structure, they can sometimes become noticeable indoors despite a reasonable outdoor sound level.
For this 24K version, Fujitsu indicates an outdoor sound level of approximately 49 dB(A) in cooling mode and 50 dB(A) in heating mode.
A proper installation therefore aims to achieve two different things:
- limiting the noise produced by the machine itself;
- preventing mechanical vibrations from being amplified by the structure supporting it.
The vibration-dampening components visible on this installation directly contribute to the second objective.
A compact outdoor unit despite its substantial capacity
The heat pump shown in the photo appears imposing because it is viewed up close, but the outdoor unit of the 24K model remains relatively compact for its capacity.
The Fujitsu specifications indicate approximately:
- 632 mm high;
- 799 mm wide;
- 290 mm deep;
- 53 kg net weight.
This relatively limited depth is useful when a unit must be installed on a roof, a mechanical terrace, or in a location where we need to maintain walkways around the equipment.
Nevertheless, the installation clearances specified by the manufacturer must always be respected. A compact machine does not mean it can be enclosed between obstacles.
A TRÈS2 rating of 24.0 for this capacity
The 24K model in the ORION XLTH series has a TRÈS2 of 24.0, along with a TRE2 of 12.5 and a regional V CPSC2 of 9.4, according to Fujitsu’s technical table.
The range is also presented with ENERGY STAR ratings, including the cold-climate designations indicated by Fujitsu.
These figures are particularly useful when we compare heat pumps with similar capacities.
A homeowner can easily encounter two units, each labeled “24,000 BTU,” even though their electricity consumption, low-temperature capacity, modulation, and seasonal efficiency are very different.
That is why at AirGreen, we analyze the complete system, not just the number printed on the box.
Rebates: always verify the exact model rather than just the brand
An ENERGY STAR-certified cold-climate heat pump may be of interest in the context of various energy-efficiency programs, but eligibility for a heat pump rebate should never be assumed solely because the unit bears the Fujitsu or ORION XLTH name.
Programs may require:
- a specific combination of indoor and outdoor units;
- an eligible AHRI reference;
- a given capacity;
- an installation meeting specific criteria;
- proof of purchase and installation;
- certain building characteristics.
We therefore recommend verifying eligibility using the exact model numbers ASUH24KZAS and AOUH24KZAH1 whenever financial assistance is part of the purchasing decision.
R32 and A2L marking: what we can see directly on the installation
The photo from Saint-Bernard-de-Michaudville clearly shows two markings on the unit: R32 on the front panel and A2L on the side.
Fujitsu documentation specifies that this series uses R32 refrigerant and compares its global warming potential with that of R410A. The manufacturer states a GWP of 675 for R32 versus 2088 for R410A, representing an announced reduction of 68%.
For us, the transition to R32 mainly means that installation and technical service work must follow the appropriate procedures and use equipment suitable for the refrigerant being used.
Replacing an old heat pump should never be treated as a simple physical swap between two same-sized units.
From pipe selection to future service: the details that determine the true quality of an HVAC installation
This 24K version uses 3/8 in. and 5/8 in. lines
The model shown in the photograph is also a good example of the importance of checking the refrigerant piping during a replacement.
For the 24K system, Fujitsu specifies:
- 3/8 in. for the liquid line;
- 5/8 in. for the gas line.
The specified minimum piping length is 5 m, or 16 ft, while the maximum length can reach 50 m, or 164 ft. The specified maximum vertical difference is 30 m, or 98 ft.
These figures offer considerable flexibility when designing the route between the indoor and outdoor units.
They also show why we never assume that existing piping will automatically be suitable.
The other capacities in this same family also use different diameters. Replacing a 12K with a 24K, for example, cannot be assessed solely by checking whether the old lines “still seem suitable.”
An electrical supply suited to the actual capacity
The AOUH24KZAH1 version operates at 208 to 230 V, 60 Hz, single-phase, and the specification sheet indicates a 20 A circuit breaker for this capacity.
The indicated rated power consumption is:
- 1.76 kW in cooling mode;
- 1.86 kW in heating mode.
The indicated maximums are 3.05 kW and 3.55 kW, respectively.
These characteristics must be considered during project planning so that the electrical supply is designed for the equipment actually being installed.
An indoor unit designed for quiet operation
Although the project photo primarily highlights the outdoor unit, the homeowner’s comfort obviously also depends on the operation of the indoor wall-mounted unit.
For the 24K model, Fujitsu specifies several fan speeds in addition to Auto mode.
In Quiet mode, the advertised indoor sound level drops to approximately 30 dB(A). The unit also has a washable filter and automated vertical airflow direction.
Page 3 of the documentation also mentions the highly corrosion-resistant copper ProCore coils, several operating modes, a backlit remote control, and various control options.
Built-in Wi-Fi for remote control
The ORION XLTH series also features integrated Wi-Fi connectivity with remote monitoring through the AIRSTAGE mobile app, according to Fujitsu documentation.
This function is useful for a heat pump used as the primary heating appliance for an area: the owner can adjust the settings without being physically in front of the unit.
It can also make it easier to manage a residence whose occupancy varies throughout the week.
Mistakes this installation helps prevent
This rooftop project in Saint-Bernard-de-Michaudville is an excellent example of several mistakes we systematically strive to avoid:
- placing the outdoor unit directly on an unsuitable surface;
- overlooking the clearance required beneath the heat pump during winter;
- forgetting to manage defrost water;
- rigidly mounting the unit without considering vibrations;
- choosing the piping based on the old equipment rather than the new model;
- installing a heat pump too close to an obstacle that could disrupt its airflow;
- making the equipment difficult to access for future HVAC maintenance;
- sizing solely according to the floor area without considering the building’s actual heat losses.
The support visible in the photo is therefore not merely an accessory. It is part of the installation strategy.
An installation that must remain practical several winters after it is commissioned
At AirGreen, we judge an installation not only by its appearance on the day we complete the work, but also by how it will age.
In a few years, a technician may need to clean the heat exchanger, check the connections, diagnose a problem, or perform maintenance.
The unit must therefore remain stable and accessible.
On this FUJITSU ORION XLTH 24K installation in Saint-Bernard-de-Michaudville, the elevated structure, vibration-isolation points, clearance around the unit, and the refrigerant line route visible on the side create a much more practical configuration than equipment simply placed as low as possible on the roof.
This same approach is applied to our installations of wall-mounted heat pumps in Montreal, Laval, Longueuil, on the North Shore and the South Shore, whether it is a small 9,000 BTU residential unit, a high-efficiency 12,000 BTU model, or a larger-capacity heat pump such as this FUJITSU 24K.
The quality of an HVAC system depends on the combination of three elements: proper sizing, the right equipment, and an installation suited to the building. When these three elements are handled with the same level of rigor, the heat pump can truly deliver the performance for which it was designed.