A flat roof installation, designed to last and perform in the Montreal climate
At AirGreen , we just installed a Sharp ZU1 (R-32) wall-mounted heat pump on the flat roof of a triplex in Plateau-Mont-Royal . The client's goal was clear: to achieve efficient, quiet, and stable heating/cooling all year round, without encroaching on the backyard or the brick facade. Our team designed a rooftop installation that respects the membrane, ensures optimal clearances, and facilitates access for HVAC maintenance .
Why the Sharp ZU1 for this building?
Sharp's ZU1 series is a safe bet for new-generation wall-mounted heat pumps with R-32 refrigerant . It combines high-efficiency inverter technology , comfort in heating mode even in very cold weather, and Plasmacluster Ion technology for healthy indoor air. On an old building in the Plateau, these advantages translate into:
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Significant energy savings thanks to fine modulation of the compressor.
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Reliable heating in cold weather (low temperature operating range).
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Improved air quality (reduction of odors, allergens, bacteria).
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Low visual footprint inside; all noise is confined to the roof.
Our flat roof installation strategy
Installing a wall-mounted heat pump condenser on a flat roof requires more than just a "deposit." Here's the AirGreen method implemented on this project:
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Roof rails with EPDM soles : we installed aluminum rails with rubber soles (EPDM) which distribute the load and prevent any puncture of the membrane.
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Treated wood joists and anti-vibration supports : the condenser is raised on joists to rise above areas where water and snow accumulate, with silent blocks under the fixings. Result: less vibration and increased longevity.
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Refrigerant Connection Route : The refrigerant lines and 240V power supply are routed through UV-capped conduits to the sealed passage. The insulation is UV-resistant and double-sealed at the ends to prevent condensation.
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Condensate management : in air conditioning mode, evacuation is by gravity to a point provided on the roof, with a guard siphon to prevent the return of odors.
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Standard clearances : the unit complies with the required clearances around vents and walls visible on the roof, guaranteeing air intake/exhaust without recirculation.
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Membrane protection : all support points are detached and no fixings have pierced the covering; the penetrations are made in an existing service frame , then sealed by our partner roofer.
The challenges specific to Plateau-Mont-Royal… and our solutions
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Access and handling
The Plateau's roofs are often served by narrow exterior staircases. We planned a hoist route from the alleyway, with protection for the railings and steps. The device and rails were lifted in a single sequence to reduce the time spent blocking the alleyway. -
Wind and chimney effect
The Plateau's flat roofs are subject to variable winds. We oriented the condenser with its back to the prevailing wind in the area and mechanically anchored the assembly to the rails using the recommended method for uplift loads, while preserving the membrane (anchoring in the rails, not in the roof). -
Solar radiation and maintenance
The unit benefits from a partially shaded area thanks to mature trees and the adjacent low wall, limiting summer overheating. We have left a service corridor of at least 60 cm on each side useful for maintenance and cleaning of the batteries.
Rigorous commissioning: what makes the difference
In the photo, we can see our vacuum frame and manifold during the commissioning phase. Our protocol includes:
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Deep vacuum draw to a value that meets industry standards.
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Vacuum resistance (stability) to validate the integrity of solders and connections.
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Weighing and load adjustment if the total length exceeds that preloaded by the manufacturer.
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Electrical checks : voltage/differential, dedicated circuit breaker, disconnect conformity.
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Functional controls for heating and cooling, with delta T readings inside and pressure/temperature readings at the condenser.
This treatment prevents premature refills , incomplete oil returns and degraded performance that are too often seen after “quick” installations.
Result for the customer: comfort, silence and free space
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Quiet inside : the wall-mounted head works at low speed thanks to the inverter; noise is transferred to the roof, away from the living areas.
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No footprint : the courtyard remains available; no snow guard was necessary on the ground, and the aesthetics of the facade are preserved.
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Simplified service access : interior filters can be removed in seconds; roof-side clearances ensure safe seasonal maintenance.
AirGreen best practices for installation on a flat roof (to remember)
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Wide and elastomer supports : always place EPDM soles under the rails.
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Minimum elevation of 10 to 15 cm to avoid stagnant water and ice.
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UV insulation on the connections; avoid tight bends.
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Distance from vents (burnt gas, cooking) to prevent fin corrosion and odors.
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Condensate management : favor gravity; if pump, provide service hatch and antifreeze protection.
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Winter plan : post-snow check, clearing around the grilles, and checking the silent blocks.
Grants and Eligibility
The Sharp ZU1 (new generation R-32 , high efficiency) meets the current criteria of efficiency programs offered in Quebec. Depending on the configuration of the residence and the energy file, the household may be eligible for incentives applicable to the efficient wall-mounted heat pump . Our team supports the client from the eligibility analysis to the submission of the documents .
HVAC maintenance: ensuring long-term performance
We offer an annual maintenance plan including:
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Cleaning of indoor/outdoor batteries, checking condensate flow;
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Electrical check and tightening of connections;
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Inspection of insulation and capping exposed to UV;
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Performance measurements (delta T, compressor intensity, indoor side static pressure).
Regular maintenance maintains performance, extends lifespan and preserves the manufacturer's warranty .
Why AirGreen?
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Expertise in typical Montreal flat roofs (Plateau, Rosemont, Southwest).
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RBQ/CMMTQ compliant installations , careful finishing, and complete documentation provided to the customer.
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Fast service throughout Greater Montreal : Montreal, Laval, Longueuil, North Shore, South Shore .
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Selection of recent brands at R-32 / R-454B to anticipate environmental requirements.
Conclusion
This Sharp ZU1 installation on a flat roof in Plateau-Mont-Royal highlights our way of working: careful design , protection of the envelope , rigorous commissioning and controlled aesthetics . The client now benefits from four-season comfort , optimized invoices and a discreet system that respects the architecture of his building.