Installation of a FUJITSU AIRSTAGE ORION XLTH+ wall-mounted heat pump in Saint-Paul-de-l'Île-aux-Noix: R-32 outdoor unit installed on a flat roof

In Saint-Paul-de-l'Île-aux-Noix, a rooftop installation where the choice of support and clearances makes all the difference

For this wall-mounted heat pump installation in Saint-Paul-de-l'Île-aux-Noix, we worked with a FUJITSU AIRSTAGE ORION XLTH+, a product line designed to provide heating and cooling in particularly demanding conditions. This time, our job-site photograph focuses on an aspect that is less visible from inside a home: the installation of the outdoor unit on a flat roof.

The context deserves closer attention. Several ventilation outlets and rooftop mechanical components are located around the heat pump. The area is relatively clear, but each location must be assessed because an outdoor unit needs sufficient airflow while remaining accessible for maintenance.

We therefore installed the unit on a raised metal structure, itself resting on a base that distributes the support points across the roof. In the photo, two long pieces of wood are also visible along the base. This type of installation avoids treating the roof as though it were simply a concrete slab on the ground. On a roof, we must consider the support, stability, vibrations, drainage, and future access to the equipment.

The heat pump itself clearly displays the FUJITSU, AIRSTAGE, and R32 identifiers. The latter is important: the ORION XLTH+ generation presented in the technical documentation uses R-32 refrigerant and is specifically designed for heating in cold climates. The brochure indicates a heating operating range down to -30 °C (-22 °F).

Why elevate an outdoor unit on a Quebec rooftop

One of the costliest mistakes in a heat pump installation is to consider only the conditions on the day the work is carried out.

On a dry day, a unit installed very close to the roof may seem perfectly functional. In January, conditions are different: snow accumulation, ice, water from defrost cycles, and significant temperature variations.

A heat pump in heating mode draws energy from the outdoor air. Under certain conditions, frost forms on the outdoor heat exchanger, and the system automatically initiates a defrost cycle. The resulting water must then be able to drain properly.

That is why the unit's height is important.

In this Saint-Paul-de-l'Île-aux-Noix installation, the metal structure keeps the unit above the immediate roof surface. This notably helps to:

• leave space beneath the heat pump;
• limit problems related to snow accumulation around the base;
• facilitate drainage from defrost cycles;
• keep the unit accessible;
• avoid direct contact with the roofing membrane.

The FUJITSU ORION XLTH+ also has a base pan heater designed for extremely cold climates, according to the manufacturer's documentation. This equipment is particularly relevant in Québec, but it can never replace a well-planned outdoor installation. The unit's technology and the installer's work must complement each other.

Several nearby ventilation outlets: a location that must be selected carefully

The photograph clearly shows that this unit is not alone on a vast empty roof. Several ducts and ventilation outlets already occupy the area.

In this kind of situation, we must avoid simply placing the heat pump in the first available space.

An outdoor unit must be able to draw in and discharge air effectively. An installation too close to an obstruction can promote air recirculation, reduce performance and complicate servicing.

We therefore assess:

• the direction of the air discharge;
• the height of nearby equipment;
• the necessary clearances around the unit;
• access to the service side;
• the route of the lines;
• the possibility of snow accumulation;
• the constraints of the roof.

This approach is particularly important for a flat-roof HVAC installation, whether the project is in Saint-Paul-de-l'Île-aux-Noix, Montréal, Laval, Longueuil, on the North Shore or the South Shore.

A compact outdoor unit that facilitates certain complex installations

FUJITSU presents the ORION XLTH+ outdoor unit as a compact model offering up to 20 metres, or 66 feet, of piping under the conditions specified in its technical data sheet. The maximum indicated vertical difference is 14.9 metres, or approximately 49 feet.

This flexibility can become particularly useful when the indoor unit is located on another level of the building.

For a rooftop installation, we must always verify the actual length of the refrigeration circuit before confirming the final location. It is not enough to estimate the straight-line distance; the actual route of the lines must be taken into account.

For the range presented, Fujitsu specifies piping of:

• 1/4 in. for the liquid line;
• 3/8 in. for the gas line.

The indicated minimum length is 3 meters, or 10 feet.

These specifications must be followed when preparing the site and selecting refrigeration equipment.

FUJITSU ORION XLTH+: why this heat pump is particularly well suited to projects requiring heating in extreme cold

Three capacities in the range, with different performance levels

The technical documentation provided with this project presents three ORION XLTH+ configurations:

• 09KTAP1 : 9,000 BTU/h nominal cooling capacity;
• 12KTAP1 : 12,000 BTU/h nominal cooling capacity;
• 15KTAP1 : 14,500 BTU/h nominal cooling capacity.

The nominal heating capacities are 12,000, 15,300, and 17,400 BTU/h, respectively.

The outdoor photo does not show the nameplate clearly enough to identify with certainty which of these three capacities applies to the installation shown. We therefore prefer to preserve this distinction rather than inventing a tonnage or BTU rating.

This is also good advice for homeowners: when a contractor simply refers to a “Fujitsu ORION,” always ask for the exact combination of the indoor and outdoor model numbers.

The documentation specifically identifies the following combinations:

• ASUH09KTAS / AOUH09KTAP1;
• ASUH12KTAS / AOUH12KTAP1;
• ASUH15KTAS / AOUH15KTAP1.

Very high seasonal efficiencies

The technical sheet lists TRÈS2 values of:

• 33.5 for the 09 version;
• 31.5 for the 12 version;
• 28.7 for the 15 version.

The regional V CPSC2 values are 11.5, 11.3, and 10.7, respectively. All three configurations also carry the ENERGY STAR ratings indicated in the Fujitsu documentation.

These figures allow capacities to be compared within the same product family, but they should never be used alone to size a project.

Excellent performance on paper does not compensate for poorly selected capacity or improper installation.

Heating capacity that remains impressive at very low temperatures

The main advantage of the ORION XLTH+ for an installation in Quebec remains its performance when the outdoor temperature drops sharply.

Fujitsu publishes maximum heating percentages at different temperatures. At -26 °C, the documentation indicates:

• 147% for the 09 model;
• 128% for the 12 model;
• 116% for the 15 model.

Even at -30 °C, the indicated values are 113%, 103%, and 101%, respectively, based on the measurement conditions explained by the manufacturer.

For us, this information is much more useful than the simple claim that a heat pump “operates at -30 °C.”

The real question is rather how much capacity it retains when it is very cold.

This is particularly relevant in Saint-Paul-de-l'Île-aux-Noix, where purchasing a wall-mounted heat pump is often motivated as much by heating needs as by summer cooling.

Inverter technology: adapting output rather than constantly operating at maximum capacity

The FUJITSU AIRSTAGE ORION XLTH+ uses an Inverter compressor.

The principle is to vary the system's capacity according to actual needs. When there is a high demand for heating or cooling, the system increases its output. When the indoor temperature approaches the setpoint, it can reduce its output.

This modulation helps achieve:

• more consistent temperature;
• fewer on-off cycles;
• more stable comfort;
• generally quieter operation at reduced load;
• energy use better adapted to demand.

For equipment designed to operate during a large part of the winter, this behavior is particularly interesting.

R-32: clearly identifiable on the photographed unit

A small detail visible on the front of the outdoor unit deserves particular attention: the identification R32.

Fujitsu explains in its brochure that R-32 has a global warming potential of 675 according to the reference used, compared with 2088 for R-410A, representing a 68% reduction in the comparison presented by the manufacturer.

For the homeowner, it may seem to be nothing more than a refrigerant difference.

For our technicians, this also means that the preparation, tools, and work methods must be compatible with the installed system. A new generation of equipment must be accompanied by appropriate installation practices.

Support stability: a detail invisible from inside, but essential on the roof

In the photo, the structure supporting the machine is clearly visible.

This part of the project deserves as much attention as the unit itself.

A heat pump contains a compressor and a fan that generate movement and slight vibrations during operation. On a foundation wall or slab, these vibrations are transmitted in a certain way. On a roof, the behavior may be different.

We therefore need to look for an installation that is:

• stable;
• level;
• sufficiently rigid;
• suitable for the equipment's weight;
• compatible with the roof surface;
• accessible without compromising the membrane.

Depending on capacity, the outdoor units in the product line shown weigh approximately 86 to 97 lb. The load is therefore not enormous compared with certain central systems, but that never justifies an improvised installation.

Beware of roof penetrations

When working on a flat roof, every potential penetration must be treated with caution.

A heat pump installation should not create a future water-infiltration problem.

Whenever possible, we plan the supports and the technical route in a way that preserves the existing watertightness. When penetrations are necessary, they must be made and sealed using a method appropriate for the roofing system.

This is one of the major differences between a ground-level installation and a project at height: the building's watertightness is part of the HVAC equation.

The best location should also facilitate future maintenance

We always think about the technician who may return a few years later.

It must be possible to:

• remove the service panels;
• check the connections;
• access the valves;
• clean the heat exchanger;
• take electrical measurements;
• inspect the drain and piping;
• perform work without having to move several neighboring pieces of equipment.

In the photo of this installation in Saint-Paul-de-l'Île-aux-Noix, the unit remains accessible from the front and has a generous amount of working space in front of it.

This detail may seem insignificant during installation, but it becomes particularly important when HVAC maintenance or repairs are required.

A system also designed to operate quietly

The outdoor unit's sound levels vary according to capacity.

The specification sheet indicates, among other things:

• 44 dB(A) for the 09 version;
• 48/49 dB(A), depending on the mode, for the 12 version;
• 51/49 dB(A) for the 15 version.

Fujitsu also mentions a low-noise operating mode for the outdoor unit.

However, the actual perceived noise level depends heavily on the installation.

On a roof, we must consider not only airborne sound, but also vibrations that can travel through the building structure. This is another reason why the choice of support should never be treated as a mere finishing detail.

ENERGY STAR and grants: verify the exact combination before calculating financial assistance

The FUJITSU specification sheet lists the three capacities along with the ENERGY STAR ratings applicable to the product line.

This is an important consideration when a homeowner is looking for a heat pump eligible for financial assistance.

However, eligibility for a grant should never be determined solely by the logo shown on a brochure.

We recommend checking:

1. the exact indoor and outdoor unit numbers;
2. the corresponding AHRI or ENERGY STAR reference;
3. the installed capacity;
4. the criteria of the financial assistance program in effect at the time of installation;
5. the documents required to submit the application.

Programs and amounts may change. It is therefore preferable to confirm the eligibility of the specific system rather than assume that all machines bearing the same commercial name automatically qualify for the same amount.

This project clearly illustrates our approach to more complex installations

A photograph of a completed unit can sometimes give the impression that the installation itself is simple.

In reality, this FUJITSU ORION XLTH+ project in Saint-Paul-de-l'Île-aux-Noix involves several technical decisions: determining a viable location on a roof already occupied by mechanical equipment, providing a support structure that is high enough, preserving airflow, managing the lines, and keeping the unit accessible.

In addition, there are all the steps that the photo does not show:

• refrigerant line connection;
• insulation;
• power supply;
• communication between the indoor and outdoor units;
• circuit testing and preparation;
• vacuuming;
• commissioning;
• verification of heating and cooling operation.

That is precisely where field experience matters.

What homeowners should keep in mind before a rooftop heat pump installation

A quality heat pump such as the FUJITSU AIRSTAGE ORION XLTH+ provides an excellent technical foundation. But it still needs to be installed in an environment that allows it to operate properly.

For a flat-roof project, we recommend paying particular attention to clearance, height above the snow, support stability, winter drainage, vibrations, watertightness, and service accessibility.

These are exactly the principles we apply at AirGreen for our installations in Saint-Paul-de-l'Île-aux-Noix and throughout Greater Montreal, including Montreal, Laval, Longueuil, the North Shore, and the South Shore.

The result we seek is not simply a heat pump that starts properly on the day of installation. We want a system whose location, supports, and connections remain logical after several summers, several winters, and numerous defrost cycles.

This rooftop installation clearly demonstrates that philosophy: a FUJITSU ORION XLTH+ R-32 designed for cold climates, installed on an elevated structure and carefully integrated among the building’s existing equipment.