A flat roof installation designed for the Montreal climate and the longevity of the membrane
At AirGreen , we have just installed a Sharp ZU1 (R-32) wall-mounted heat pump in a home located in Saint-Henri, in the Southwest of Montreal . A special feature of the project: the outdoor unit is installed on a typical Montreal flat roof , while the wall-mounted head serves the main living area. This project illustrates our expertise in HVAC installation when access is at height, the membrane must be protected, and the equipment must remain reliable and quiet all year round.
The choice of equipment: Sharp ZU1, stable comfort and efficiency in 4 seasons
The Sharp ZU1 belongs to the new generation of wall-mounted heat pumps using R-32 refrigerant , recognized for:
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fine modulation thanks to the Inverter compressor , maintaining a constant temperature without overconsumption;
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high efficiencies (SEER/HSPF optimized) to reduce electricity bills;
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cold weather operation suitable for Greater Montreal, with efficient defrosting and comfortable blowing;
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controlled acoustics , both indoors and outdoors, essential in a dense urban environment like Montreal .
Depending on the configuration, this range is eligible for local subsidies — a significant asset for our customers in Montreal, Laval, Longueuil, the North Shore and the South Shore .
Building context and client objectives
The owner wanted:
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Efficiently cool and heat the main open area;
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Maintain the roof's watertightness and avoid vibrations;
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Limit the visual impact on the courtyard and alleyway side;
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Facilitate HVAC maintenance and access to the electrical disconnect.
We therefore proposed a wall-mounted installation on the interior side and a condenser on the roof , sheltered from view and shocks, with a short and clean refrigeration path.
Our method for Montreal flat roofs: precision, protection, performance
Membrane support and protection
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Raised aluminum chassis : it places the unit at the right height to evacuate defrost water in winter and ensure air circulation in accordance with the manufacturer's clearances.
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Load-bearing footings : We distributed the load on pads/footings placed on rigid insulation so as not to puncture the membrane. This approach protects the waterproofing and simplifies roof inspections.
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Vibration management : combination of rigid support and damping supports to reduce vibration transmission to the structure — a crucial point for acoustic comfort in plexes and condos.
Refrigeration and finishing
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Single, watertight and insulated drilling near the parapet for a short connection route (insulated copper + communication cable).
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UV capping to match the envelope, installed with outward slopes to prevent stagnant water.
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Gravity-driven indoor head condensate management , with continuous slope to the discharge point — a quiet and reliable solution.
Electricity and safety
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Roof disconnect switch , accessible and identified for any maintenance work.
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Mechanically sized and protected cabling throughout, with service loops for maintenance and future load checks.
Air circulation and clearances
We have respected the side and rear clearances in order to optimize heat exchange and facilitate cleaning of the coil . The orientation of the fan prevents the recycling of hot air in summer and limits the accumulation of frost in winter.
Commissioning and quality checks
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Nitrogen leak tests then deep vacuum until stabilization;
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Validation of supply currents and voltage ;
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Calibration of parameters for gradual modulation and soft restart;
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HVAC maintenance advice provided to the customer (filter cleaning, seasonal inspection, condenser washing).
Why the Sharp ZU1 is so well suited to Saint-Henri
The buildings of the South-West combine old membrane roofs, sometimes narrow access and close proximity . In this context, the ZU1 stands out for:
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its compactness , facilitating installation on chassis without encroaching on access paths;
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its low noise level , useful for terraces and roof terraces;
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its mid-season stability , avoiding short cycles in homes with changing thermal loads.
Concrete benefits observed after commissioning
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Uniform and rapid comfort in the open area, without drafts;
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Predictable cost reduction compared to existing electric baseboards;
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Silence in night mode , useful in the quiet streets of Saint-Henri;
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Aesthetics preserved : no unity in the courtyard, no drop on the facades.
AirGreen Tips for Sustainable Flat Roof HVAC Installation
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Protect the membrane first : favor supports without drilling , with load distribution and clear access paths.
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Plan for snow : Keep 15–30 cm under the unit for frost/defrosting and avoid snow drifts against the condenser.
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Think about maintenance : clearances, accessible disconnect, secure access hatches .
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Regular maintenance : annual condenser wash, clean filters, spring inspection of bindings and routes.
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Optimize the interior : position the wall head to sweep the living area without blowing directly on the occupants.
Our promise: a turnkey project, with no surprises
From thermal study to commissioning , we manage every detail: capacity selection (BTU), electrical compliance, roof protection, applicable subsidies , and HVAC maintenance . Our teams cover all of Greater Montreal — Montreal, Laval, Longueuil, North Shore, South Shore — with clear deadlines and transparent prices .
Result: performance, silence and preserved roof
This Sharp ZU1 installation in Saint-Henri demonstrates that a properly sized, roof-mounted heat pump can provide four-season comfort , remarkable efficiency , and minimal visual impact . At AirGreen, we combine detailed engineering and meticulous workmanship to create systems that last—and remain easy to maintain.