Four-season comfort in a space with cathedral ceilings and skylights
At AirGreen , we carry out HVAC installations that respect the architecture of Montreal homes while maximizing energy efficiency. This project, located in Plateau-Mont-Royal , presented a specific challenge: air conditioning and heating a large volume with a cathedral ceiling crossed by skylights , without compromising aesthetics or wall space. The chosen solution, a high-efficiency Fujitsu wall-mounted heat pump , perfectly meets the client's comfort needs, reduces dependence on electric baseboards and blends discreetly into the decor.
The context: a luminous volume, variable thermal loads
The living room is bathed in natural light thanks to two large southwest-facing skylights. This configuration provides significant solar gain during the day in summer and significant loss at night in winter. The main wall already has an electric baseboard heater at the base of the wall: typical of Montreal apartments, efficient as a supplement but energy-intensive.
Our objectives:
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ensure uniform cooling without drafts felt under the skylights;
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guarantee stable heating even in very cold weather thanks to the heat pump ;
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preserve the visual purity of the volume and the circulation on the ground.
The chosen equipment and its advantages
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Type : wall-mounted heat pump (mini-split).
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Brand : Fujitsu (high efficiency wall-mounted range, low temperature compatible).
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Capacity : sized for a large open living room (high ceiling), calculated after thermal assessment (envelope, orientation, glazed surface).
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Performance : high coefficients in air conditioning and heating; performance maintained at -25°C , meeting the requirements of the subsidy programs in force in Quebec when combined with other eligibility criteria.
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Acoustics : very low noise level indoors and outdoors, ideal in dense urban environments.
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Control : infrared remote control, time programming and Wi-Fi module compatibility (optional) for remote management.
Wall-mounted head installation: strategic height and controlled diffusion
The interior head is placed high on the living room gable , under the ridge, a good distance from the skylights. This choice:
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completely frees up low wall space, useful for furniture;
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promotes controlled stratification : the blown air descends in a layer and homogenizes the temperature of the volume;
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avoids the direct impact of solar rays on the probe, ensuring a reliable reading of the ambient temperature.
We adjust the directional shutters so that the flow bypasses the roof glazing area, minimizing the effect of a hot wall in summer and a cold wall in winter. The flow rate is set to Auto mode with different day/evening profiles to optimize comfort without unnecessary noise.
Refrigeration path and condensate evacuation: clean, short and discreet
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Drilling : single, from the head to the adjacent attic, sealed and insulated.
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Refrigerant connections : routed through the attic then exited to the outside; limited length to limit pressure losses and optimize efficiency.
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Capping : white finish to match the walls and woodwork; clean, watertight transitions.
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Condensate : gravity drainage to the outside with a controlled slope; the route prevents any water stagnation. A backflow preventer and an odor eliminator complete the system.
Outdoor condenser: discretion, protection and performance in winter
For this type of unit, two common layouts are common in Montreal: flat roof on an anti-vibration support with snow guards, or courtyard/backyard on a raised slab. Here, the outdoor unit is installed on a raised support, free from snow accumulations and protected from potential ice falling from skylights. The layout complies with:
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the manufacturer's recommended clearances ;
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air circulation without recirculation;
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management of defrost condensates (free flow, no ice cubes under the battery).
Silent blocks limit vibration transmission to the building and neighbors—as important for comfort as for compliance.
Electricity and compliance: safety and sustainability
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Dedicated circuit from the panel, rating in accordance with the maximum current of the unit;
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double-pole circuit breaker and external disconnect box near the condenser;
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UV-resistant and properly anchored outdoor wiring ;
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insulation tests and pressure gauge leak check before commissioning;
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vacuum placed at 500 microns then stabilized, loading according to the actual length of the line;
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controlled start-up and verification of pressures at stabilized speed, in air conditioning and heating.
Construction site challenges and technical responses
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Cathedral ceiling & stratification
High volumes encourage the accumulation of warm air at the ridge. We use a high installation height and a calculated blowing angle to break up stratification, supported by a moderate fan speed in heating mode to avoid excessive mixing while bringing the heat back to the occupied area. -
Skylights & localized overheating
The airflows were directed to sweep across the opposite wall and not directly hit the windows. The result: uniform temperature and the elimination of hot pockets that would trigger short cycles in summer. -
Aesthetics & integration
All the cappings follow the lines of the volume, passed through the attic as much as possible to leave the wall clean . The finishes are made in a matte white palette, invisible from the living area.
Results observed after commissioning
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Rapid cooling of the living room on a sunny afternoon; the target temperature is reached without any drafts.
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Stable heating from dusk, with a significant reduction in the use of electric baseboards .
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Imperceptible noise level during conversation; cycles are long and regular, a guarantee of efficiency and durability .
Recommended HVAC Maintenance: Maintain Performance
To maintain the performance and longevity of the heat pump :
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Clean filters every 4 to 8 weeks during periods of heavy use;
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Annual inspection by our technicians: heat exchange, fan, condensate tray, electrical tightening, operating pressure, cleaning of the outdoor unit (fins);
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Winter clearance of the outdoor unit: at least 45 cm free all around after each snowfall.
Grants and savings: what the owner gains
High-efficiency wall-mounted heat pumps like Fujitsu are generally eligible for grants available in Quebec when the installation meets performance and implementation criteria. We support our clients in:
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validate eligibility (performance, operating temperature);
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prepare the required documents (quotes, detailed invoices, proof of installation);
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optimize the financial structure and the work schedule.
On a daily basis, the reduction in consumption linked to direct electric heating (baseboards) constitutes the bulk of the savings, amplified by the efficiency of the heat pump in mid-season.
Why AirGreen for a Montreal home with an atypical volume?
Our teams understand the constraints of Plateau-Mont-Royal housing: historic load-bearing walls, narrow attics, roof access, snow and ice management, and coexistence with existing electric baseboard heaters . We provide:
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appropriate sizing engineering (thermal load, orientation, air renewal rate);
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careful implementation (waterproofing, acoustics, aesthetics);
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comprehensive support (grants, warranty, HVAC maintenance ).
We operate daily in Montreal, Laval, Longueuil, North Shore and South Shore , with controlled deadlines and responsive after-sales service.
Conclusion
This Fujitsu wall-mounted heat pump installation in Plateau-Mont-Royal proves that a cathedral ceiling space can benefit from uniform comfort without visual compromise. By combining thermal studies, installation at the right height, and careful attention to detail (gravity condensate, discreet cappings, winter protection), we deliver a reliable, quiet, and economical system, ready to face Montreal's climate all year round.