A clean and sustainable urban construction site: optimization of a HVAC installation on a flat roof, with anti-vibration, controlled refrigeration path and careful sealing for four-season comfort in Montreal .
Context and objectives of the project
In the heart of Rosemont–La Petite-Patrie , a Montreal plex with a reflective white roof needed a high-performance heating and air conditioning system that would be stable in winter and discreet for the neighborhood. The clients wanted:
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A heat pump that heats efficiently in cold weather (down to −30°C).
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Installation on a flat roof to keep the facades clear and limit noise in the interior courtyard.
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A solution compatible with current provincial grant programs, subject to eligibility.
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Easy maintenance and safe access for service visits.
After thermal analysis of the unit, losses and roof constraints, we recommended a Midea Midea28 (new generation R-454B ), in a single-zone wall-mounted configuration.
Why Midea Midea28 (R-454B) for this building
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High heating and cooling efficiencies , adapted to the Montreal climate.
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Resilience in intense cold (extreme cold operating range) to reduce electrical backup.
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New generation refrigerant (R-454B) , aligned with environmental developments.
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Low noise level, ideal for a dense urban setting.
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Remote control and fine modes (intelligent defrosting, stable temperature maintenance to protect interior finishes).
Reading the site and preparing
Before any HVAC installation , we carry out:
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Inspection of the roof membrane (condition, slopes, drainage points).
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Survey of outlets (vents, skylights) in order to respect clearance distances and avoid recirculation of hot air.
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Verification of admissible loads and distribution via supports.
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Tracing of the shortest refrigeration route , protected from the sun and shocks, with slopes for condensate management.
Flat roof installation details
Support and anti-vibration
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Outdoor unit placed on weighted rails mounted on EPDM pads to protect the membrane and filter vibrations.
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Condenser orientation perpendicular to the prevailing winds in order to stabilize the pressures on the battery.
Electrical and safety
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Waterproof outdoor disconnect switch (grey box, IP-rated) installed within easy reach for maintenance.
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Wiring under UV sheath and mechanical fixing at regular intervals (safety and wind resistance standards).
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Dedicated circuit breaker to the panel, rating and wiring conforming to the nominal load of the Midea28.
Refrigeration and finishing
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Insulated copper connections (≈ 9 m total including the vertical rise) routed in white capping to the roof crossing.
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Nitrogen brazing and deep vacuum (< 500 microns) with nitrogen leak test before commissioning.
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Respect the radii of curvature and slopes to avoid oil pockets.
Condensate management
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Gravity discharge prioritized when the slope allows. If the interior configuration requires it, silent condensate pump with non-return and defrosted line.
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Outlet positioned so as not to obstruct passage areas or mark the membrane.
Waterproofing and roofing
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Crossing by membrane compatible sleeve and flashing , sealed with recommended roofing mastic, with flaps and reinforcements.
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Distribution slabs under rails and pads to avoid any punching.
Commissioning and controls
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24-hour pressurization and manometric observation (when required by the configuration).
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Stabilized vacuum : rise test to exclude residual humidity.
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Settings : heating/cooling mode, hysteresis, fan speeds, economy priority adjustment.
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Spot thermography of connections and control of intensities at start-up.
Results obtained
From the first week of use:
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Stable indoor temperature throughout the floor, benefiting from the gentle diffusion of the wall unit.
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Reduction in noise perceived in the courtyard and on the facade thanks to installation on the roof and anti-vibration treatment.
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In off-season heating mode, the Midea28 covers most needs without additional heating, improving operating costs .
HVAC Use and Maintenance Tips
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Keep the internal filters clean (vacuum monthly during periods of intensive use).
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Check the release of air inlets around the condenser (leaves, dust).
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Schedule annual preventive maintenance : battery cleaning, current monitoring, inspection of seals and the disconnect switch.
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In winter, clear snow around the unit and check the defrost drains.
What makes AirGreen different in Montreal, Laval, Longueuil, North Shore and South Shore
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Mastery of Montreal flat roofs : we respect membranes, loads and access.
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Clean and traceable installation: legible refrigeration paths, compliant supports, secure electricity.
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Selection of new generation equipment (R-454B / R-32) and transparent advice on subsidies where applicable.
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Local and responsive after-sales service , with stocks of common parts to limit delays.
Pitfalls to avoid (feedback)
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Rigid supports directly on the membrane: risk of punching and transmission of vibrations. We use EPDM pads and distribution rails.
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Insufficient clearances near roof vents: hot air recirculation and loss of efficiency. We maintain safe distances and proper orientation.
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Discontinuous or poorly secured capping : UV and weather damage the insulation. We install continuous paths with regular anchors.
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Absence of a disconnector or poor IP protection: non-compliance and maintenance risks. A waterproof disconnector is systematically installed.
Key technical data (Rosemont–La Petite-Patrie project)
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Equipment : Midea Midea28 wall-mounted heat pump (R-454B), single zone.
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Installation : flat roof, anti-vibration rails on pads, anti-recirculation orientation.
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Connections : ≈ 9 m insulated copper, vacuum draw, nitrogen pressure test.
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Electrical : IP external disconnector, circuit dedicated to the panel.
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Finishes : UV capping, sealed roof crossing, controlled condensate drainage.
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Service : annual maintenance recommended; AirGreen assistance in Montreal , Laval , Longueuil , North Shore and South Shore .
Deadlines and coordination
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Technical visit and structural validation: 48–72 hours after contact.
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Delivery, installation and commissioning : generally one day for a similar configuration (excluding weather or access constraints).
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Coordination possible with the roofer for additional sealants and strips when the owner wishes.
And for your building?
Each building has its own specific features (roof access, cooling distances, permissible noise level, maintenance requirements). Our AirGreen team sizes and installs suitable wall-mounted and central heat pumps , favoring recent R-454B / R-32 ranges and sustainable installation methods. For a documented quote with photo survey and route plan, we intervene quickly in Montreal , Laval , Longueuil , North Shore and South Shore .