Installation of a Fujitsu AIRSTAGE Aquila XLTH dual-zone heat pump in Saint-Nazaire-d’Acton

A high-mounted installation on a brick façade, designed for two zones and a demanding Quebec winter

At Saint-Nazaire-d’Acton, we installed a Fujitsu AIRSTAGE Aquila XLTH dual-zone heat pump at a brick-fronted home. The project immediately stands out because of a detail visible in the photograph: the outdoor unit was installed high up on wall brackets, and the refrigerant lines run almost to the soffit inside a long vertical line cover that matches the façade.

This configuration was not chosen at random. It addressed several specific technical needs: protecting the unit from snow accumulation, keeping it off the ground, maintaining convenient access around the building, keeping the installation orderly despite the presence of two refrigerant circuits, and ensuring a clean exterior finish across a large masonry surface.

The photo also shows a long ladder extended along the wall. This clearly illustrates one of the challenges of this project: working at considerable height to route the lines to the two indoor zones. Such an installation requires meticulous planning, both for safety and for line routing, anchor quality, compliance with allowable lengths, and more.

Why a dual-zone heat pump was suitable for this home

A dual-zone heat pump allows two indoor units to be connected to a single outdoor unit. This solution is particularly useful when two areas of the home need to be treated separately, without adding two outdoor units to the façade.

In a home in Saint-Nazaire-d’Acton, needs can vary greatly between two rooms or two floors. One zone may be more exposed to sunlight, have more windows, or be located beneath a roof that gets hotter in summer. Another may experience greater heat loss in winter.

With a multi-zone system, each indoor unit can be adjusted independently. Occupants can, among other things:

• choose a different temperature in each zone;
• turn off a unit when the room is unoccupied;
• adjust the fan speed;
• adjust the louvers separately;
• schedule the zones according to separate schedules.

According to Fujitsu documentation, H-series AIRSTAGE multizone systems can power several types of indoor units, including wall-mounted units, Slim Duct units, compact cassettes, and certain Mid Static Duct units. The manufacturer also specifies that each indoor unit can be controlled independently, even though the system must operate in one shared general mode: heating or cooling, but not both simultaneously.

In other words, one zone can be stopped while the other operates, but one room cannot be heated while another is being cooled at the same time.

An elevated outdoor unit that remains functional despite snow

The photograph clearly shows that the Fujitsu outdoor unit is installed several feet above ground level. This height offers several advantages in a climate like Quebec’s.

In winter, a unit placed too low may be affected by:

• snow accumulating around the coil;
• ice forming beneath the chassis;
• reduced airflow;
• difficult access for maintenance;
• debris thrown by a shovel or snowblower;
• more problematic defrost cycles.

When a heat pump operates in heating mode, its outdoor coil may accumulate frost. The system then initiates a defrost cycle, producing water that must be able to drain freely.

By installing the appliance on elevated wall-mounted supports, we create significant space beneath the unit. This helps manage defrost water more effectively and reduces the risk of snow quickly reaching the bottom of the appliance.

Robust wall-mounted supports and fastening suited to masonry

The unit rests on a triangulated metal structure attached to the wall. This type of support must be properly sized and carefully anchored.

An outdoor heat pump is not only heavy. It also generates vibrations and is affected by wind. The supports must therefore withstand:

• the appliance’s static weight;
• compressor vibrations;
• startup cycles;
• wind;
• temperature variations;
• seasonal building movements.

On a brick façade, it is essential to determine where the load-bearing structure is located and which type of anchor is appropriate. Facing brick should not automatically be considered a sufficient structural material.

We specifically check:

• masonry quality;
• anchor placement;
• anchoring depth;
• support level;
• load distribution;
• the stability of the unit;
• the necessary clearances at the rear and on the sides.

A slightly tilted unit may vibrate more and make water drainage more difficult. Leveling is therefore an integral part of the quality of the HVAC installation.

A long vertical line-set cover that protects both circuits

One of the most visible elements of this project is the large brown line-set cover that rises almost to the top of the wall.

In a dual-zone installation, several components must be routed from the outdoor unit to the two indoor units:

• two sets of refrigerant lines;
• the insulation for each line;
• the communication cables;
• the required conductors;
• the condensate drains, depending on the configuration;
• the connections and transitions.

Leaving these elements exposed would have compromised the façade’s durability and appearance. We therefore grouped them inside a rigid line-set cover.

The chosen color matches the shade of the brick and the building’s dark architectural elements. This visual integration is particularly important when a vertical run extends over almost the entire height of the house.

Why the length of the run matters

The longer the run, the more precisely we must check:

• the total length of each circuit;
• the height difference between the outdoor unit and the indoor units;
• the limits permitted by the manufacturer;
• the refrigerant charge;
• the bending radii;
• insulation;
• the fastening of the lines.

A long, poorly supported run can vibrate, sag, or transmit noise to the structure.

We therefore fasten the line-set cover at regular intervals and avoid unnecessary changes in direction.

The importance of safety when working at height

The tall ladder visible in the photo highlights an essential aspect of the project: access to the upper sections of the wall.

When the lines must rise near the soffit, the installation becomes work at height. We must plan:

• access;
• the stability of the ladder;
• the handling of the lines;
• the transport of the equipment;
• the fastening of the line-set cover;
• the safety of the technicians;
• the protection of the windows and masonry.

A refrigerant line must never be forced or bent sharply simply because it is difficult to handle from a ladder. The bending radius must be respected to prevent the copper from being crushed.

The electrical box installed near the unit

An electrical device is visible beneath and to the right of the outdoor unit. Its location provides convenient access during maintenance or service work.

A Fujitsu heat pump must be supplied by a properly sized circuit. The electrical installation includes, among other things:

• panel protection;
• the proper conductor gauge;
• grounding;
• an accessible disconnecting means;
• communication wiring;
• connection verification.

In a two-zone system, the wiring must also correspond precisely to each refrigeration circuit. Reversing two zones can lead to inconsistent operation: a controller may call for the wrong unit.

We therefore identify each circuit during installation and test the two zones separately before final commissioning.

The Fujitsu Aquila XLTH: a multi-zone configuration that must be selected methodically

The different capacities of the H Series

Fujitsu documentation indicates that H Series AIRSTAGE systems can use 18,000, 24,000, 36,000, or 45,000 BTU/h outdoor units. Depending on the model selected, they can power up to two, three, four, or five indoor units.

For the two-zone configuration, the table on page 2 presents several approved combinations, including:

• 7,000 + 7,000 BTU/h;
• 7,000 + 9,000 BTU/h;
• 7,000 + 12,000 BTU/h;
• 7,000 + 15,000 BTU/h;
• 9,000 + 9,000 BTU/h;
• 9,000 + 12,000 BTU/h;
• 9,000 + 15,000 BTU/h;
• 12,000 + 12,000 BTU/h.

The exact capacity of the outdoor unit shown in the photograph cannot be confirmed with certainty from the image alone. We therefore do not infer its BTU rating solely from the cabinet size.

An approved combination is not enough to validate a project

Fujitsu’s tables make it possible to confirm which units can be connected together. However, they do not replace a complete sizing assessment.

The manufacturer also indicates that these tables should not be used alone for capacity selection and recommends using its Design Simulator software.

We analyze in particular:

• the floor area of each zone;
• heat losses;
• solar gains;
• insulation;
• ceiling height;
• glazed area;
• wind exposure;
• piping length;
• height difference;
• low-temperature capacity;
• the likelihood of simultaneous use of both zones.

Two zones with equal floor areas may require different capacities depending on their orientation and thermal envelope.

A connection capacity exceeding 100%

Fujitsu indicates that certain multi-zone units can accept a total indoor-unit capacity of up to 130% of the outdoor unit’s nominal capacity.

This does not mean that the outdoor unit produces 130% of its nominal capacity. The manufacturer clearly states that exceeding 100% does not increase the total production capacity.

When both zones require substantial capacity at the same time, the outdoor unit distributes the available capacity.

This concept is important for homeowners who compare only the numbers shown on the wall-mounted units.

Operation in extreme cold

Fujitsu documentation for the H series indicates that CTEB units designed for cold climates can continue operating in heating mode down to -26 °C. It also mentions an inverter compressor and several built-in protection features.

This information is particularly relevant in Saint-Nazaire-d’Acton, where the heat pump must be able to contribute to heating for a large part of the winter.

However, it is important to distinguish between:

• minimum operating temperature;
• available heating capacity;
• performance at that temperature.

A heat pump’s capacity changes as the outdoor temperature drops. We therefore check the actual performance of the exact model before determining whether supplemental heating will be necessary.

The inverter compressor and comfort in both zones

The Fujitsu system uses an inverter-driven compressor. It can modulate its speed according to demand.

When the load is low, the compressor can slow down instead of operating only at full capacity. This helps to:

• maintain a more stable temperature;
• reduce on and off cycles;
• adjust energy consumption;
• distribute capacity between the zones;
• reduce comfort variations;
• limit certain fluctuations in sound levels.

In a dual-zone system, this modulation is particularly useful when one of the two zones quickly reaches its setpoint while the other continues to call for heating or cooling.

Managing condensate from indoor units

Each indoor unit produces water when operating in cooling mode. This water must be drained properly.

In a project where the units may be located at significant heights, we need to plan the drains from the outset.

We check:

• the slope;
• the length;
• the discharge point;
• passages through walls;
• the risk of freezing;
• maintenance options;
• the possible need for a condensate pump.

A poorly designed drain can cause a leak several weeks after installation, especially during a very humid period.

Mistakes to avoid when installing an outdoor unit at height

Installing the unit too high without considering maintenance

Snow protection is useful, but the unit must remain accessible for servicing.

Using insufficient supports

Weight, vibrations, and wind must be taken into account.

Underestimating the length of the lines

A long run may require a charge adjustment or additional verification.

Installing the line-set cover without proper alignment

A very long vertical run makes even the slightest misalignment immediately visible.

Making bends in the copper too tight

A crushed line can reduce performance and create long-term problems.

Neglecting access to the electrical box

The disconnect must remain accessible.

Allowing the lines to vibrate inside the cover

Improper fastening can transmit noise through the wall.

Our commissioning procedure

Before handing the system over to the customer, we perform a series of checks:

1. checking the outdoor unit’s level;
2. inspection of the wall brackets;
3. checking the anchors;
4. checking the clearance around the heat exchanger;
5. inspection of the line-set cover;
6. checking the bend radius;
7. pressure test;
8. leak test;
9. vacuuming;
10. wiring verification;
11. identification of both circuits;
12. testing the first zone;
13. testing the second zone;
14. simultaneous operation of both units;
15. heating test;
16. cooling test;
17. checking the drains;
18. an explanation of the controls to the owner.

This commissioning confirms that the two zones correspond to their respective circuits and that the installation operates as intended.

An installation adapted to the constraints of Saint-Nazaire-d’Acton

This installation demonstrates that a Fujitsu Aquila XLTH dual-zone heat pump can be cleanly integrated into a large brick façade, even when the indoor units are located at a considerable height.

The distinctive elements of this project include:

• a raised outdoor unit;
• sturdy wall brackets;
• a protected long vertical run;
• an exterior finish matching the façade;
• organized electrical access;
• an installation adapted to snow;
• two zones powered by a single outdoor unit;
• complete commissioning.

At AirGreen, we install dual-zone heat pumps in Saint-Nazaire-d’Acton, as well as on the South Shore, in Longueuil, Montreal, Laval, and on the North Shore. Each project is adapted to the building’s actual structure, height restrictions, climate, and the manufacturer’s technical requirements.