Installation of a Fujitsu AIRSTAGE Orion XLTH wall-mounted heat pump on a flat roof in Sainte-Anne-de-Sorel, Montérégie

In Sainte-Anne-de-Sorel, a Fujitsu Orion XLTH installation where the real challenge was on the roof

For this installation carried out in Sainte-Anne-de-Sorel, the most interesting result is not found solely inside the building. The site photograph clearly shows what sets this project apart: the outdoor units Fujitsu AIRSTAGE Orion XLTH were installed on a flat roof, on raised supports, near existing ventilation equipment.

For a wall-mounted heat pump, the positioning of the outdoor unit is just as important as that of the indoor wall-mounted evaporator. On a roof, we must contend with circumstances that differ greatly from a standard ground-level installation: snow accumulation, ice resulting from defrost cycles, roof drainage, stronger winds, access for maintenance, and the need not to compromise the roofing membrane.

The photograph shows two Fujitsu outdoor units arranged in the same technical area. The unit in the foreground is mounted on a raised metal frame. Beneath this structure, support elements can be seen distributing the load across the roof surface rather than allowing the machine to rest directly on the roofing. The refrigerant lines and wiring are neatly grouped along the side. The marking R32 is also visible directly on the Fujitsu casing.

This is exactly the type of project where an apparently simple installation actually requires a great deal of thought before the heat pump is even turned on.

Why raise a heat pump installed on a roof?

In Sainte-Anne-de-Sorel, as elsewhere in Montérégie, an outdoor unit installed on a roof must continue operating when conditions become much less favorable than in summer.

During the winter, a heat pump must contend with, among other things:

• snow accumulation;
• freeze-thaw cycles;
• water produced during defrosting;
• ice that may form beneath or around the unit;
• stronger gusts on an exposed roof;
• the necessary access for future HVAC maintenance.

The structure visible in this installation keeps the Fujitsu unit above the immediate roof surface. This helps prevent a machine intended to operate during the winter from being too close to an area where snow, water, or ice could accumulate.

This precaution makes even more sense with a cold-climate heat pump.

Fujitsu documentation indicates that the AIRSTAGE Orion XLTH line can operate in heating mode down to -26 °C. The series shown includes the 09KZAH1, 12KZAH1, 15KZAH1, 18KZAH1, and 24KZAH1 capacities.

A machine capable of heating at this temperature must be installed in a way that allows it to breathe, drain defrost water, and remain accessible even when outdoor conditions are difficult.

Installing a heat pump on a flat roof requires a different approach to HVAC

When we install a heat pump at ground level, it is generally possible to work on a slab, base, or wall-mounted support.

On a flat roof, the priorities change.

Protecting the roof

The membrane and the roof structure are integral parts of the project. We avoid treating the roof as a simple platform on which to place a machine.

The unit must be stable, but the load must also be managed appropriately. In the photo, the system is not simply sitting directly on the gravel: we can see a support structure that creates a more organized and accessible installation.

Preserving access to other equipment

Another visible element in the photo is the proximity of a roof vent. In this type of configuration, we must allow enough space around the equipment to facilitate future maintenance.

A heat pump can operate for many years. During that time, it may be necessary to inspect:

• the electrical connections;
• the refrigerant connections;
• the outdoor heat exchanger;
• the fan;
• the drainage;
• the support;
• the lines;
• nearby rooftop equipment.

An installation squeezed in solely to save a few inches can make every future service visit much more complicated.

Fujitsu Orion XLTH: a product line designed for heating in cold climates

Choosing a Fujitsu Orion XLTH is particularly appropriate when a homeowner wants to use their heat pump as a true heating system rather than solely as an air conditioner with an occasional heating function.

The Fujitsu technical sheet indicates a heating operating range from -26 °C to 24 °C, while cooling operation is intended for temperatures between -10 °C and 50 °C.

The outdoor unit also uses an Inverter compressor. This technology makes it possible to modulate capacity according to the building's needs rather than operating solely according to an on-off logic.

Under real-world conditions, this modulation is useful because demand is never the same throughout the day. A heat pump may need to provide a great deal of heat in the morning, then gradually reduce its output as the sun warms the building.

A base pan heater that is particularly relevant to this project

The page devoted to the Orion XLTH series specifications indicates that the outdoor unit is equipped with a base pan heater designed for extremely cold climate regions.

On a rooftop installation like this one, this characteristic requires our particular attention.

A heat pump operating in heating mode must regularly defrost its outdoor coil when frost forms on it. The defrost cycle produces water, which must be able to drain properly. When the outdoor temperature is very low, this water can obviously freeze again.

This is one of the reasons why we place so much importance on the unit's height, its support, and the space available beneath the machine.

R-32 is visible directly on the installed machine

In the photo of the Sainte-Anne-de-Sorel project, the R32 marking is clearly visible on the right side of the outdoor unit.

Fujitsu states that the Orion XLTH series uses this refrigerant and compares its global warming potential with that of R-410A. According to the documentation provided, the listed GWP drops from 2,088 for R-410A to 675 for R-32, representing a reduction of 68 %.

For us, however, the switch to R-32 is not merely environmental information. It also involves technical considerations during installation.

Equipment must be installed according to the manufacturer's specific requirements, and we never assume that old piping or a previous installation is automatically suitable for a new heat pump.

Five Orion XLTH capacities, with different performance levels

Fujitsu documentation presents several variants of the product line.

Their nominal cooling capacity is as follows:

• 09KZAH1: 9,000 BTU/h;
• 12KZAH1: 12,000 BTU/h;
• 15KZAH1: 14,500 BTU/h;
• 18KZAH1: 18,000 BTU/h;
• 24KZAH1: 22,000 BTU/h.

The nominal heating capacities are respectively 12,000, 16,000, 18,000, 21,600 and 25,200 BTU/h.

The exterior photo does not make it possible to read the nameplate precisely enough to confirm which of these capacities corresponds to the unit in the foreground. We therefore do not artificially assign it a BTU rating.

This point may seem secondary, but it is essential when discussing a professional HVAC installation. Two visually similar Fujitsu units may have different piping, electrical power, and performance specifications.

High energy efficiency ratings depending on the capacity selected

The series has TRÈS2, or SEER2, values ranging from 24.0 to 33.1:

• 09KZAH1 : 33,1;
• 12KZAH1 : 30,5;
• 15KZAH1 : 27,5;
• 18KZAH1 : 25,5;
• 24KZAH1 : 24,0.

The regional V CPSC2 values provided by Fujitsu range from 9.4 to 10.7 depending on capacity.

The technical data sheet also classifies the models shown as ENERGY STAR, including the designations associated with cold climates.

For a homeowner looking for a heat pump eligible for financial assistance, this certification is important information. Actual eligibility and the amount of a grant must nevertheless always be verified using the exact combination of indoor and outdoor models, as well as the program rules in effect on the installation date.

Performance at -26 °C: more useful figures than a simple operating threshold

A common mistake when comparing heat pumps is to stop at the statement “operates down to -26 °C.”

We prefer to look at the actual capacity remaining as the temperature drops.

The Fujitsu data sheet specifically provides the maximum heating percentage at very low temperatures. At -26 °C, it indicates:

• 127% for the 09KZAH1;
• 102% for the 12KZAH1;
• 109% for the 15KZAH1;
• 106% for the 18KZAH1;
• 80% for the 24KZAH1,

according to the calculation method described by Fujitsu in the technical data sheet.

For a homeowner in Sainte-Anne-de-Sorel who wants to reduce their use of traditional electric heating, this type of data deserves much more attention than the simple advertised minimum temperature.

Why sizing remains essential

Installing the largest available Orion XLTH would make no sense if the building does not need it.

Sizing depends on several factors:

• area actually served;
• ceiling height;
• insulation quality;
• air infiltration;
• glazed area;
• window orientation;
• interior configuration;
• floors;
• location of the wall-mounted unit;
• building’s heat load.

A good wall-mounted heat pump in Sainte-Anne-de-Sorel is one whose capacity matches the building’s actual needs.

Oversizing can impair the unit’s performance at partial load, while undersizing can limit heating capacity when demand becomes significant.

Different piping dimensions depending on the model

The Orion XLTH series also demonstrates why replacing an old heat pump must be carefully evaluated.

Fujitsu specifies the following diameters:

• 09KZAH1: liquid 1/4 po, gas 3/8 po;
• 12KZAH1: liquid 1/4 po, gas 3/8 po;
• 15KZAH1: liquid 1/4 po, gas 1/2 po;
• 18KZAH1: liquid 3/8 po, gas 5/8 po;
• 24KZAH1: liquid 3/8 po, gas 5/8 po.

For a rooftop installation, this aspect is particularly important because the route between the indoor and outdoor units can be much longer and more complex than with a unit simply installed on the exterior wall behind the evaporator.

Up to 50 metres of piping for certain capacities

Fujitsu allows a maximum piping length of:

• 25 m for the 09 and 12 models;
• 30 m for the 15 model;
• 50 m for the 18 and 24 models.

The maximum permitted vertical difference also varies from 20 m to 30 m depending on capacity.

This flexibility makes certain projects easier, where the outdoor units must be grouped on a roof while the indoor units are located in different parts of the building.

That does not mean, however, that long piping is desirable by default. At AirGreen, we always seek a coherent, accessible route that complies with the manufacturer’s limits.

Several outdoor units should remain organized when grouped together

The photograph shows at least two Fujitsu units installed in the same roof area.

When a building requires several heat pumps, grouping the equipment can produce a more orderly result, but the machines must not be placed so close together that their airflow or technicians’ access is compromised.

We must therefore think of the roof configuration as a small mechanical area.

Each unit must be able to:

• draw in enough air;
• expel air without significant obstruction;
• be accessible for cleaning;
• be repairable without having to dismantle the neighboring installation;
• allow inspection of the connections;
• remain compatible with the operation and maintenance of the other roof equipment.

This type of organization is part of installation quality, even if occupants hardly ever go onto the roof.

The electrical requirements also vary according to capacity

The entire Orion XLTH series presented operates on a 208 to 230 V, 60 Hz, single-phase power supply.

However, the specified breaker rating varies:

• 15 A for the 09KZAH1 and 12KZAH1 models;
• 20 A for the 15KZAH1, 18KZAH1, and 24KZAH1 models.

This is another reason why we never recommend replacing a heat pump based solely on its physical dimensions.

Capacity, refrigerant lines, and electrical supply must be considered together.

This Sainte-Anne-de-Sorel project shows why a professional installation goes beyond the machine

A beautiful heat pump can be improperly installed

Product quality cannot compensate for poor placement.

A Fujitsu AIRSTAGE Orion XLTH can offer particularly impressive performance, but several mistakes can reduce the expected benefits:

Placing the unit too close to the roof

This can make the unit more vulnerable to the accumulation of snow, ice, or water.

Blocking access to the service side

A repair that should have been simple then becomes unnecessarily time-consuming.

Neglecting drainage during defrosting

The Quebec winter quickly turns poor drainage into an accumulation of ice.

Running the lines without proper organization

Poorly protected or inadequately supported lines make future work more difficult and compromise the overall quality of the installation.

Choosing capacity based solely on price

A difference of a few hundred dollars should not lead to installing a system that is improperly sized for the building.

Ignoring the roof’s specific characteristics

Drainage, structure, other equipment, and technician access must all be taken into account.

A compact outdoor unit designed for demanding work

Fujitsu also describes the outdoor unit as compact and equipped with a low-noise operating mode. The documentation indicates outdoor sound levels ranging from approximately 46/47 dB(A) to 49/50 dB(A), depending on the model and heating/cooling mode.

On a roof, this feature can be beneficial because the equipment is sometimes located above bedrooms, dwellings, or occupied spaces.

The actual noise level inside the building also depends on the support, the roof structure, and how vibrations are transmitted. That is why we always consider the mechanical installation part of acoustic comfort.

What we take away from this AirGreen installation in Sainte-Anne-de-Sorel

This project highlights a less visible aspect of our work at AirGreen.

The client wanted to benefit from the heating and cooling provided by a Fujitsu Orion XLTH wall-mounted heat pump, but the building’s configuration required an outdoor rooftop installation.

We therefore had to approach the project not only as heat pump installers, but as HVAC specialists dealing with the realities of a Quebec flat roof: elevating the units, routing the lines, ensuring future access, working around existing mechanical equipment, and maintaining winter operation.

The result visible in the photo is clean and well organized: the Fujitsu units are grouped together, elevated, and installed on dedicated supports, while the lines are routed along the mechanical area.

For a homeowner in Sainte-Anne-de-Sorel, Montreal, Laval, Longueuil, on the North Shore or the South Shore, this project above all highlights one thing: a high-end heat pump only reaches its full potential when it is installed according to the actual building.

At AirGreen, we therefore strive to offer more than just a machine. We analyze the location, sizing, electrical requirements, piping, airflow, drainage, and future maintenance so that the installation remains practical for many years after we leave.

The Fujitsu AIRSTAGE Orion XLTH offers features particularly well suited to Quebec: heating down to -26 °C, R-32 refrigerant, Inverter technology, a base pan heater, ENERGY STAR certification, several available capacities, and detailed low-temperature performance data.

Our role is then to install this technology in conditions that allow it to truly do its job.