A thoughtful winter installation: snow clearance, silence and maintenance access on flat roofs
At AirGreen , we carried out the HVAC installation of a Sharp wall-mounted heat pump (ZU1 series, R-32 refrigerant) on a flat roof of a duplex in the Côte-des-Neiges–Notre-Dame-de-Grâce (NDG) neighborhood. The work took place in the middle of winter: heavy snow accumulations, cold winds, access by ladder and hopper. Our objective: to guarantee reliable heating at very low temperatures , preserve the integrity of the roof and maintain a minimal noise level for the immediate neighborhood.
Why the Sharp ZU1 series for the Montreal climate
The Sharp ZU1 is a recent wall-mounted heat pump that operates on R-32 , a more efficient fluid with a lower GWP than R-410A. For residences in Montreal and the surrounding area, it meets the following requirements:
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Heating efficiency down to approx. −25°C , relevant during cold spells in NDG, Outremont and the entire west-central part of the island.
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Fine modulation inverter compressor : controlled consumption, stable comfort and fewer on/off cycles.
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Low exterior and interior noise levels – an asset for narrow alleys and shared rooftops.
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Air quality enhanced by Sharp's Plasmacluster technology on the indoor side.
The selected capacity efficiently covers an open living room-kitchen area and adjacent rooms, with a margin for cold peaks without relying on expensive energy backup.
Designing a flat roof installation: the challenges to master
Installing a condenser on a flat roof in winter requires long-term thinking . We structured the project around four axes:
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Protection against snow and ice
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Placed on a raised aluminum frame , providing significant clearance under the base to prevent burial during snow drifts and to guarantee drainage in defrosting mode.
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Useful height sized to the district (wind corridors in NDG) and to historical accumulations.
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Orientation of the air discharge to limit re-icing on the fins.
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Respect for the envelope and waterproofing
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Route of refrigerant connections to the heart of the house by sealed penetration (sleeve, flashing, membrane-compatible mastic).
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UV and mechanical protection of lines via rigid cover; curvature radii respected.
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Vibrations and noise
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Anti-vibration mounts under the chassis to decouple the transmissions from the structure.
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Alignment and torque tightening to avoid harmonics in inverter mode.
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Maintenance and security access
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360° clearance around the device for maintenance and diagnostic operations.
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Clear surface and secure pedestrian path from the roof access; owner awareness of courtesy snow removal around the unit.
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Execution Details: What We Put in Place
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Fixing the frame : appropriate seals and distribution pads to avoid puncturing the membrane.
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Drain in defrost mode : free discharge, away from stagnation areas; when necessary, we provide a heating resistor on the critical section (not required here due to the clearance).
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Electrical : dedicated section with compliant circuit breaker, disconnection box within easy reach, UV-sheathed cables.
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Refrigeration tests : nitrogen test, deep vacuum , load control according to the actual length of lines , then reading of pressures and intensities at hot/cold.
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Calibration : activation of eco/silent modes, configuration of automatic defrosting, verification of ΔT.
Result: comfort and serenity in the middle of winter
The owner benefits from stable heating even in very cold weather, controlled bills thanks to inverter modulation and a discreet noise level for neighbors. The raised installation considerably reduces the risk of burial and ice under the unit , preserving heat exchange and the lifespan of the system.
AirGreen Best Practices for Any Flat Roof HVAC Installation
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Always raise the outdoor unit above the local snow line .
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Clearances : Maintain manufacturer's clearances for suction and discharge; avoid L-shaped walls or unventilated shafts.
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Defrosting drain : provide an ice-free area; avoid drains directed towards pathways.
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Anti-vibration : adapted pads and controlled tightening; revisited after the first winter-spring cycle.
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Membrane : interpose protective soles and use compatible products (solvent levels, adhesion).
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Access : plan the service (sockets, disconnection, tool passage) from the design stage.
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HVAC maintenance : an annual visit remains the best guarantee of performance/durability.
Recommended maintenance: maintain performance year after year
We offer a maintenance plan that includes:
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Cleaning and inspection of batteries and external fan ;
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Checking electrical connections , condition of UV covers and insulation ;
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Refrigeration checks (superheat/subcooling), updating defrost parameters ;
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Checking the studs and chassis stability after winter;
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Usage tips: maintain a constant setting , clean the interior filters every 6 to 8 weeks during the season, and clear snow around the unit.
Grants and administrative support
The Sharp ZU1 R-32 has an energy efficiency profile aligned with assistance programs generally offered in Quebec (e.g., eco-grants for performance improvements and heating load reduction). At AirGreen, we:
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assess eligibility based on installed configuration;
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prepare supporting documents (bid, serial numbers, installation photos);
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guide the client to maximize the return on investment.
Why AirGreen in NDG, Montreal, Laval, Longueuil, North Shore and South Shore
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Recognized expertise in flat roofs , plexes and small buildings typical of Greater Montreal;
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Certified technicians on Sharp, Gree, Fujitsu, Midea, and other popular brands;
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Standardized quality process (controls, tests, documentation, delivery to the customer);
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Complete service : estimate, installation, HVAC maintenance and rapid troubleshooting .
Conclusion
This Sharp ZU1 installation on a flat roof in NDG illustrates our approach to a winter construction site: prevention of snow-related risks , silence , maintenance access and impeccable waterproofing . The result: four-season comfort and real durability for the residence, summer and winter, with a contained visual impact and optimized operating costs.