A raised installation, designed for Montreal flat roofs: free air circulation in the snow, safe maintenance and silence in the interior courtyard
Urban context and objectives
In Plateau-Mont-Royal , typical flat-roofed buildings require a tailored HVAC approach: tight clearances, close neighbors, roof access via hatches or exterior stairs, and wind- blown snow that accumulates in drifts. Our client wanted reliable heating for a renovated top-floor apartment, discreet air conditioning in the summer, and an installation designed to last without compromising the roof's watertightness.
We recommend aSharp wall-mounted heat pump ( single-fan outdoor unit, inverter ) – model from the ZU1 range (R-32 refrigerant) – coupled with a main wall-mounted indoor head , with the possibility of adding a second zone later if usage evolves. The Sharp is chosen for its fine modulation, contained acoustics and low temperature stability, key criteria in dense urban environments.
Why this Sharp on a flat roof of the Plateau
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Inverter modulation : maintains a uniform temperature and saves energy thanks to continuous adjustment of the compressor speed.
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Compactness : reduced casing and single fan limiting wind resistance and noise pollution.
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R-32 : recent generation refrigerant, promoting good seasonal performance and reduced environmental impact compared to older generations.
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Easy service : accessible architecture for periodic HVAC maintenance on flat roofs.
External installation: raising and respecting the membrane
We install the unit on a raised galvanized steel support , sized for the load and wind loads . The feet rest on soles that distribute the force and preserve the membrane . The anchors are positioned according to a load plan that avoids sensitive areas (junctions, drains, waterproofing upstands).
Advantages of raised installation in snowy climates:
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Snow clearance : the fan and exchange grilles remain above the usual snowdrifts, keeping suction and blowing free.
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Defrost drainage : water drains by gravity without freezing around the frame; the area under the support remains ventilated and clear.
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Durability : The fins remain protected from compacted ice accumulations; the frame is never immersed in meltwater.
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Vibrations : Calibrated silent blocks between the unit and the support limit vibration transmission to the structure.
We scrupulously respect the manufacturer's recommended clearances on the front, back and sides to ensure optimal air circulation , even when snow shapes the landscape.
Refrigeration path and sealing
The refrigerated route follows the best short and direct line:
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Vertical path in a technical chimney then sealed drilling through the roof (fireproof foam, flashing, membrane-compatible mastic).
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UV-resistant capping to protect refrigerant lines (high-density insulated copper) and wiring to the unit.
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Service loop behind the unit for absorption of expansions and future disassembly without stress on the collars.
On the electrical side, we install a disconnect on the roof, visible and clear, powered by a dedicated circuit from the panel. The cable gauge , grounding and circuit breaker rating comply with the Electrical Code . The routes are attached outside of water stagnation to prevent icing.
Extreme cold specificities: frost, wind and acoustics
The Plateau's flat roofs are exposed to gusts . We orient the unit to reduce air recirculation and avoid direct blowing towards edges and obstacles. Sharp's Inverter defrost logic limits cycle times, which preserves indoor comfort. We provide the customer with a maintenance plan :
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Clear corridor of at least 1 m in front of the blowing facade.
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Post-storm monitoring : clear any ice ledge under the device.
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Gentle rinse of the fins in the spring, never high pressure.
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Biannual check of fixings, silent blocks and covers.
Thanks to the raised support and low speed modulation , the acoustics are very contained and barely perceptible from the interior courtyard and the alleys, a sensitive subject in this plex district.
Interior: wall-mounted headboard, draft-free comfort
The main wall unit serves the top-floor living area. Key adjustment points provided to the owner:
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Stable setpoint in heating mode; modulation does the rest and avoids jolts.
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Orient the shutters to sweep the room without drafts on the sofa or table.
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Filtration : monthly cleaning of filters during heating/air conditioning periods.
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Programming : time slots adapted to occupancy, without sudden variations.
Technical steps: precision commissioning
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Carefully shaped flares , torque-controlled collars.
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Nitrogen test with pressure resistance and drop control.
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Deep vacuum (microns), stabilization, verification of absence of humidity.
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Fluid opening and pressure/temperature measurements in hot mode.
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Electrical checks : current, voltage drops, disconnect operation.
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Controlled defrost setting and testing.
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Customer discount : maintenance booklet and seasonal usage advice.
Result: controlled comfort and respected roof
The home receives even heat despite prevailing winds. Defrost water drains freely without ice stalagmites around the frame. The roof membrane remains intact thanks to the installation plan and distribution flanges. In summer, the inverter modulation ensures discreet cooling , without disturbing the alleyways.
AirGreen Best Practices for Flat Roofs
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Design a winter access corridor : technician safety and simplified HVAC maintenance .
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Avoid improvised snow guards that recirculate blown air.
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Keep roof drains clear so that defrosting water leaves the area.
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Schedule annual maintenance : clean batteries, tighten connections, check inverter settings and update usage recommendations.
Grants and Compliance
Depending on the exact reference of the Sharp heat pump ( Energy Star certification, performance in cold climates ), assistance programs may apply in Quebec. We support our customers for Montreal , Laval , Longueuil , the North Shore and the South Shore : photos of nameplates , serial numbers , detailed invoices and required forms are carefully prepared to secure eligibility .
Project sheet — at a glance
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Location : Plateau-Mont-Royal (Montreal)
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Building : flat-roofed plex, access via roof hatch
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Type : wall-mounted heat pump (heating & air conditioning)
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Brand : Sharp — ZU1 (R-32) series model
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Exterior installation : galvanized raised support , distribution soles, silent blocks
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Route : technical chimney, UV capping , sealed drilling
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Electrical : dedicated circuit with disconnect on roof
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Strong points : stable performance in winter, contained noise , preserved roof, easy HVAC maintenance
Our commitment
At AirGreen , each HVAC installation adapts to the actual building: flat roof , narrow courtyard, neighborhood, wind, snow. Here, the Sharp + raised support + sealed path combination delivers lasting comfort, ready for all Montreal winters.