Optimize a narrow space under a metal staircase, without compromising performance or maintenance access
The context of a Plateau plex and our objectives
At AirGreen , we are working in a typical Plateau-Mont-Royal plex: red clapboard side facade, corner brick wall, green metal exterior staircase and narrow courtyard. The owner wants to improve the comfort of the main floor all year round, while keeping the circulation space free and limiting noise pollution in a shared courtyard. We offer a Sharp wall-mounted heat pump (recent range with R-32 refrigerant), known for its fine modulation and its Plasmacluster™ module favorable to indoor air quality.
Choice of equipment and consistency with the home
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Inverter technology : the machine modulates continuously, which avoids the short cycles that are common in the small volumes of Montreal plexes.
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R-32 : Reduced charge and better heat transfer than R-410A, with seasonal efficiency gains.
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Acoustics : Outdoor fan with low profile and quiet mode useful in interior courtyards.
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Plasmacluster™ : Indoor air purification popular in urban housing with limited ventilation.
Depending on the heated area and the building's permeability, we size the capacity (often 12,000 to 18,000 BTU for an open living area). The goal is to operate mostly at low and medium settings to optimize actual SEER/HSPF and comfort.
Implementation study: constraints and decisions
The site constraints are clear:
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Narrow space under the stairs;
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Two materials (cladding and brick);
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Pedestrian path along the wall;
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Shared courtyard requiring acoustic vigilance.
Our technical decisions:
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Fixing on galvanized wall brackets with extended reach , anchored in the load-bearing brick . This configuration clears the floor, frees the passage and guarantees rear/lateral clearances for air intake.
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High density silent blocks to cut vibration transmission to the masonry (near stairs).
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Raised height above the ground to protect the device from water and snow accumulations and to facilitate maintenance.
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Waterproof external disconnect box , positioned to the right of the unit for immediate access during maintenance.
Refrigeration path and power supply
The line set route is short and direct to the indoor area, with wall penetration behind the unit. We form wide bend radii to preserve the integrity of the tubes. The closed-cell insulation is continuous and UV-protected outdoors. The indoor unit drain follows a permanent gravity slope towards the outside; the drilling is inclined to prevent any water backflow.
The power supply is dedicated from the main panel of the dwelling, calibrated according to the nameplate, and protected by a suitable curved circuit breaker. The disconnection is fixed at the regulatory height, wired in conduit approved for outdoor use, with an anti-drip loop before entering the box.
Installation and anchoring: precision and durability
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Drillings made in the brick with chemical sieves to anchor the stainless steel studs; tightening controlled to the torque.
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Leveled brackets to avoid mechanical stress on the chassis and to maintain quiet operation.
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Clearances respected on the sides and front for air circulation, despite the nearby staircase.
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Corrosion protection on all exposed cuts and fasteners.
Instrumented commissioning
Our commissioning protocol guarantees performance and reliability:
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Pressure-controlled nitrogen test on the complete assembly.
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Deep vacuum (< 500 microns) maintained without rising during the stabilization period.
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Opening and balancing valves ; checking supply/return temperatures.
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Manifold readings and clamp thermometry to confirm thermal drift under different fan speeds.
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Acoustic control at 1 m and 5 m; adjustments as needed (tightening, leveling, blade/obstacle check).
A commissioning report always accompanies the HVAC installation, with serial numbers, photos and readings.
Results achieved for the client
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Stable comfort in winter and summer; modulation reduces perceived temperature differences.
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Lower consumption compared to previous auxiliary heaters thanks to partial load operation.
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Careful integration : clear passage, clean aesthetics, simplified maintenance thanks to accessible disconnection.
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Silence in the inner courtyard : choice of night speed and effective anti-vibration support.
Details visible on the installation
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Framed wall bracket , reach arms adapted to wall and staircase alignment.
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Clean capping and routing, regular radius, continuous insulation.
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Disconnection on the right, within easy reach, covered against the weather.
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Clearance above ground for defrost drainage and no water stagnation.
Good practices and pitfalls to avoid (in dense environments)
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Anticipate recirculation : avoid directing air discharge towards walls or under an enclosed staircase.
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Raise correctly : installation that is too low encourages the blades to be buried by snow and freeze.
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Take care of the drain slope : a drain without slope or one that is too exposed will freeze and can cause overflows.
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Limit line length : short, isolated routes = better performance and less noise.
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Observe the clearances required by the manufacturer and by the applicable code for safety and maintenance.
Maintenance and sustainability
Annual HVAC maintenance is recommended:
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cleaning of interior/exterior exchangers;
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electrical tightening and checking of intensities;
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visual inspection of insulation and anchor points;
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purge and drain test.
We schedule a callback with the client at the beginning of winter and early summer. Keeping the area free of leaves and dust between visits ensures consistent performance.
Yields, operating costs and subsidies
Recent generation R-32 wall-mounted heat pumps offer high mid-season COPs and remain efficient in cold weather. In Greater Montreal ( Montreal , Laval , Longueuil , North Shore , South Shore ), they are generally eligible for assistance programs targeting electrical energy efficiency. We assist the customer in putting together the file (technical certificates, photos, detailed invoice).
Why entrust your Plateau project to AirGreen?
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Urban expertise : we are familiar with the constraints of alleys, exterior staircases, shared courtyards and mixed brick/cladding walls.
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Finishing and compliance : dimensioned supports, stainless steel screws, chemical anchors, complete documentation.
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Local service : teams based in Greater Montreal, rapid interventions and expert HVAC maintenance .
Next step
Whether you are in Plateau-Mont-Royal , Rosemont , Le Sud-Ouest or Ville-Marie , our teams design and build clean, efficient and durable HVAC installations — from selecting the heat pump to final adjustment, including the grant application.