A flat roof installation designed to last, efficient in summer and winter
At AirGreen , we are finalizing an HVAC installation that showcases our expertise in urban environments: a Gree wall-mounted heat pump whose condenser is installed on the flat roof of a residential building in Rosemont–La Petite-Patrie . The client's objective is clear: to ensure four-season comfort with an economical inverter machine, while respecting the building's architecture and roof waterproofing regulations. We are therefore designing a clean, safe, and accessible route for maintenance, prioritizing reliability and discretion.
Project context and performance criteria
The apartment, located on the top floor of a typical plex in the area, suffered from excessive heat in the summer and a lack of temperature uniformity in the spring and fall. The client wanted:
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a quiet wall-mounted solution inside;
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a discreet external unit , without aggressive anchoring in the roof membrane;
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an energy-efficient system capable of heating at low temperatures;
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careful integration to limit visual impact and facilitate maintenance.
Our recommendation is a Gree wall-mounted heat pump (residential inverter range), known for its low-temperature heating performance and the reliability of its components (DC compressor, modulating fan, protected electronic cards).
Flat roof installation: structural approach and waterproofing
The outdoor unit is installed on a treated wooden frame resting on the roof, with anti-vibration pads under the condenser feet. This choice has several advantages:
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Load distribution to protect the roof membrane;
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Absorption of vibrations and reduction of noise transmitted to the building;
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Zero perforation of the membrane: the waterproofing of the roof is preserved.
We maintain a safe setback from curbs and rainwater runoff areas. The unit is oriented to free the exchange facade and promote unobstructed airflow (essential for performance in air conditioning mode and defrosting in heating mode). Sufficient ground clearance is maintained to prevent water or ice from accumulating under the unit's tray during thawing periods.
Refrigeration connections and power supply: cleanliness of the route
The route of the connections follows a short and readable path:
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Continuously insulated refrigeration piping , protected by a resistant UV sheath ;
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Communication and power cable secured to the harness, placed on weighted supports to prevent any fluttering in the wind;
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Roof passage made according to the rules of the art through a waterproof sleeve , then brought back to the interior wall head via white capping if necessary.
Near the outdoor unit, we provide the external safety switch (disconnector) , required by the Code, to allow for disconnection during maintenance. The circuit breaker dedicated to the electrical panel provides protection adapted to the nominal current of the compressor and the reduced starting current by the Inverter.
Condensate and defrost management
In summer air conditioning, the condensate is drained from the indoor unit by gravity when the configuration allows it, otherwise by an integrated silent lift pump . On the outdoor side, the heat pump produces defrost water in winter: we clear the area under the unit so that the flow occurs naturally, away from passageways. The customer receives winter instructions (minimal clearance, monitoring of the evacuation, gentle defrosting if exceptional accumulation).
Sizing and capacity: targeted comfort, controlled consumption
The sizing is based on the actual surface area to be treated, the exposure of the housing, the insulation and the internal gains . For a main room and adjacent spaces, the range of 9,000 to 12,000 BTU/h is often ideal in a mini-split; here, we retain a capacity optimized for:
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cool down quickly during heat waves (Montreal intramural);
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heat efficiently in the off-season and provide support as needed on cold days.
Inverter modulation prevents on/off cycles, reduces noise and stabilizes temperature . This modulation reduces power consumption , especially at half load , the most frequent period of use.
Air quality and acoustic comfort
The Gree indoor unit features washable filters and fine-tuned airflow control (shutters, auto/quiet modes). We adjust the installation height to optimize air stratification : in summer, fresh air is diffused in a layer without direct airflow onto the occupants; in heating, the orientation promotes efficient and even recirculation .
On the roof, the noise level of the condenser remains low. The combination of inverter and anti-vibration mounts limits the structure-borne noise perceived in the home. The installation distances any potential repercussions on the immediate neighbors, an essential point in the dense contexts of Rosemont–La Petite-Patrie .
Security, compliance and guarantees
Every AirGreen installation follows electrical code requirements , manufacturer specifications , and good roof waterproofing practices. We:
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draw properly calibrated dedicated lines ;
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let's install an accessible external disconnect switch ;
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test the vacuum of the refrigeration circuit, then charge to the recommended weight ;
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We carry out a complete operating test (air conditioning and heating).
The customer benefits from the manufacturer's warranties on compressor and parts, and the AirGreen labor warranty , with periodic HVAC maintenance options.
Technical challenges of the project and solutions adopted
1) Roof and wind constraints
Flat roofs exposed to prevailing winds can cause vibrations and horizontal stresses. We properly ballast the support, secure the beams, and check for possible expansion of the connections to prevent abrasion. Pipe bend radii are respected to protect the compressor.
2) Invisible and waterproof route
Between the roof and the interior, we avoid unnecessary crossings , prefer a single clean roof pass-through , and treat the junctions with a membrane-compatible sealant . Inside, the white capping extends the finish while leaving access to the connections for future maintenance.
3) Service access
We define a clear area in front of the outdoor unit to ensure access to the service valves , cards and fan . The customer receives a user guide : winter clearance, restart after storm, good practices during thunderstorms (surge protection recommended).
Grants and eligibility (depending on configuration)
Several wall-mounted heat pumps in the Gree range achieve high efficiencies and maintain a heating capacity at -25°C . In many cases, this performance, combined with ENERGY STAR certification , can open the door to provincial or municipal assistance programs in force. We validate eligibility model by model, provide the necessary documents (technical data sheets, AHRI ), and support our customers in Montreal, Laval, Longueuil, North Shore, South Shore in the administrative process .
Results observed after commissioning
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Rapid cooling of living spaces, even in late sunny afternoons;
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Stable supplementary heating in spring/autumn, allowing the main system to be delayed;
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Low noise level inside and on the roof;
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Clean finish : tidy cables, protected connections, logical and discreet route;
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Guaranteed maintenance access , from the roof to the interior head.
Operating and maintenance tips to maximize service life
Routine maintenance (owner)
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Rinse/vacuum the inner head filters every 4 to 8 weeks during periods of heavy use;
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Maintain clearances around the outdoor unit, remove leaves and dust;
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In winter, carefully clear the defrost drain area;
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Avoid cutting the power continuously: let the inverter manage the modulation.
Preventive maintenance (AirGreen)
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Annual inspection : pressure/load, electrical tightening, cleanliness of the evaporator and condenser, condensate control;
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Checking the supports and ducts on the roof (UV, abrasion, expansion);
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Update parameters if necessary (modes, shutters, specific calibrations).
Our HVAC maintenance contracts cover these points and extend equipment reliability , while keeping performance and consumption at the lowest.
AirGreen expertise serving Montreal's flat roofs
This Gree wall-mounted heat pump installation in Rosemont–La Petite-Patrie illustrates our expertise in urban flat-roof environments: suitable supports, respected waterproofing , clean paths and optimized condenser orientation. We support our customers in Montreal, Laval, Longueuil, the North Shore and the South Shore from the choice of model to commissioning , with a single priority: lasting, quiet and energy-efficient comfort , supported by responsive after-sales service .
Planning a similar project? Our team offers on-site assessment , precise sizing , and careful installation that adheres to industry best practices. At AirGreen, every project is designed to perform today and remain easy to maintain tomorrow .