A flat roof construction site optimized for longevity, silence and service access
On a typical building in the Plateau-Mont-Royal , our team is installing twoGree wall-mounted heat pumps (new generation R-32 ) with outdoor units installed on the flat roof . The objective is clear: to guarantee four-season comfort for stacked dwellings, while respecting the constraints of a masonry building with a brick parapet and vegetation at the edge. We favor a discreet, safe and sustainable approach, designed for the Montreal climate and for the reality of long-term maintenance.
Client context and needs
The owner wanted:
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a reliable reversible system for additional heating in winter and air conditioning in summer;
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a rooftop installation to free up the street and courtyard facades, reduce noise transmission to the housing and simplify maintenance access;
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a recent R-32 technology, more efficient and with a lower GWP than older generations.
What makes the difference in a rooftop HVAC installation
Mechanical installation: stability and silence
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Supports on soles : each condenser rests on UV-resistant soles, separated from the gravel to distribute the loads and prevent sinking.
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Anti-vibration : elastomer pads under the supports to cut off vibration transmission to the structure; result: minimal noise pollution in the homes.
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Peripheral clearance : we maintain the required space around the batteries to optimize heat exchange and facilitate defrosting in winter.
Refrigeration and electrical system: order and sustainability
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Insulated refrigeration connections (high density Armaflex, junctions brazed under nitrogen, leak tests before vacuuming).
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Protected path : the connections are sheathed and protected at friction points; roof penetrations receive bitumen-compatible flashings and sealants.
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Dedicated disconnect box and power supply: each machine has its own waterproof external disconnect, placed within easy reach for maintenance and compliant with the Code.
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Condensate management : gravity drainage from the interior heads to the existing columns; no free discharge onto the roof to avoid ice islands.
Safety and building envelope
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Height above gravel sufficient for air circulation and protection during episodes of partially melted snow.
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UV-sheathed wiring and stainless steel fixings to counteract oxidation accelerated by exposure on the terrace.
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Plant protection : positioning away from tree cover to prevent debris from falling into the exchangers and to reduce excessive direct sunlight.
Why the Gree R-32 wall-mounted heat pump for the Plateau?
Low temperature heating performance
The Gree R-32 wall-mounted series maintains stable performance during Montreal's cold weather. This continuous power reduces the demand on backup systems and improves operating costs during peak periods.
Efficiency and environmental impact
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R-32 refrigerant improves coefficient of performance and reduces carbon footprint compared to older blends.
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Inverter modulation precisely adjusts power to the actual load: constant comfort, extended cycles, reduced compressor wear .
Acoustic comfort
The combination of low-speed fans , anti-vibration mounts and rooftop installation keeps noise away from living areas and bedrooms—a key point in Plateau plexes with adjoining walls.
Key steps of our AirGreen method
1) Taking measurements and choosing the route
We measure the heights , parapet thicknesses , potential entry points and obstacles (ventilations, outlets, vapor barriers). The layout is determined for:
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limit the lengths of connections (≈ 10 to 15 m per route in this case);
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preserve the radii of curvature ;
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keep a clear service path .
2) Preparation of supports and controlled drilling
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Leveling of the soles; stone guards under supports if necessary.
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Adjusted diameter drillings with protective sleeves and flashings ; restoration of the roof vapor barrier to prevent any infiltration.
3) Brazing, testing and vacuuming
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Brazing under nitrogen (prevention of scale), pressure test with dry nitrogen, then deep vacuum .
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Stabilization and control of microns before opening the service valves—guaranteeing a clean and dry circuit.
4) Commissioning and balancing
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Checking currents , overheating/subcooling , supply/return temperatures, calibrating remote controls and programming nighttime noise reduction functions if required.
Result: 4-season comfort for two stacked dwellings
Each accommodation benefits from its dedicated wall head , offering:
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Precise cooling during downtown heatwaves;
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Efficient heating during the off-season and during bitter cold;
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Improved indoor air filtration .
The owner appreciates the simplified access for maintenance: the technician works from the roof without entering private areas, reducing intrusive appointments and speeding up diagnostics.
Urban HVAC Operation and Maintenance Tips
Best practices for roofing
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Seasonal clearance : Keep leaves, buds, brick dust and blown gravel away.
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Visual inspection after strong winds or freeze/thaw episodes; check that nothing is obstructing the exchangers.
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Defrosting : Let the automatic cycles run; do not turn off the power in winter.
Inside
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Regular cleaning of wall-mounted head filters (every 4 to 6 weeks during periods of use).
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Stable setpoints : avoid extreme setpoint variations so that the inverter can do its optimization work.
Professional interview
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Recommended annual visit : check of operating pressures, electrical tightening, condition of insulation, integrity of flashings, leak test, update of parameters.
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In dense environments like the Plateau-Mont-Royal , this maintenance prevents performance losses due to fine urban dust and pollen.
Grants and Compliance
Depending on the exact configuration (certified performance, capacity, and primary heating use), these R-32 wall-mounted heat pumps may be eligible for assistance programs in Quebec. We assist our clients with eligibility verification and document preparation. All our installations comply with RBQ requirements and current electrical codes .
When to call AirGreen
Whether in Plateau-Mont-Royal , Montreal , Laval , Longueuil , on the North Shore or on the South Shore , we design HVAC systems adapted to local architecture: plexes, condominiums, row houses or mixed-use buildings. Our signature: clean paths, consistent technical choices, and a turnkey project, ready for years of service.
AirGreen — Your HVAC partner in Montreal for state-of-the-art Gree R-32 wall-mounted heat pumps designed for flat roofs and urban living.